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Date: 28 Aug 2007 20:14:06
From: Artemisia
Subject: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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I've been assuming all along that the brakes I would get on my new HPV
Scorpion would be the Magura Big Hydraulic disc. I made this assumption
because in the _Greenspeed_ customisation guide, these are given as the
best choice for heavy riders in terms of max stopping power and subtlety
of control. Greenspeed, unlike HPV, doesn't offer either the Martas or
the Avids.
Now I've been reading up on the competition, and have become confused.
The Avid mechanical brakes are what come as standard. I've done some
googling on these and have found the most incredibly consistent series
of rave reviews. The consensus out there seems to be - people who fork
out extra for hydraulic discs are plain stupid or misguided, the Avids
are so good as to be unbeatable on function at a much lower price and
much easier maintenance.
I also learn that hydraulic brakes have brake fluid which can leak, and
that they are a lot fiddlier to maintain, and a lot more delicate and
likely to fail. Is this true?
And does anyone know the difference between the Martas and the Bigs?
What justifies the extra price on the Martas?
I'm not quibbling on price. I will pay _whatever_is_necessary_ to get
the product that is best for _me_. I will be using this trike to get
down the very steep hills on my commute to work. I have never been able
to bike these descents and have trouble even walking them, such is the
angle. There is about a km of dizzying descent, crossed with traffic
intersections. I _must_ be confident that I can stop.
But simplicity of maintenance is as important as powerful stopping. The
other vocation of the trike will be to come touring with me in places
where support may not be easily found, and to be on and off planes and
trains. If hydraulic disks are too delicate, and by failing immobilize
the entire vehicle, then they may not justify their extra cost.
Thanks for your experiences. Cheers,
EFR
Ile de France
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Date: 04 Sep 2007 14:39:51
From: Marz
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On Sep 4, 9:09 am, David Damerell <damer...@chiark.greenend.org.uk >
wrote:
> No, there hasn't. With a well adjusted cable rim brake you can lift the
> rear wheel (or skid the front on a poor surface). How can a hydraulic disc
> offer more braking than that? It can't.
> --
> David Damerell <damer...@chiark.greenend.org.uk> Kill the tomato!
> Today is Second Saturday, August - a weekend.
Not always true. A disk brake will offer more braking in wet, muddy
conditions than a rim brake and hence why us mtbers love 'em.
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Date: 04 Sep 2007 15:48:28
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Marz wrote:
> Not always true. A disk brake will offer more braking in wet, muddy
> conditions than a rim brake and hence why us mtbers love 'em.
Though true, that doesn't cover the qualitative difference between
hydraulic and cable systems. It seems that the better MTBs have
hydraulics, and I think that's probably about feel and consequently fine
control, possibly the difference between locking and optimum braking.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 03 Sep 2007 16:04:18
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 3 Sep, 17:30, David Damerell <damer...@chiark.greenend.org.uk >
wrote:
> Quoting Roger Merriman <N...@wodger.demon.co.uk>:
>
> >which begs the other question if tamdems have allways or for a reasonble
> >time had half decent brakes why did it not filter to mountain bikes?
>
> Because mountain bikes can't actually use any more braking than any other
> solo bike.
True, even a 30ft vertical drop only exerts the same braking force on
the brakes as a 30mph road stop, in fact probably less due to tyre
slippage.
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Date: 03 Sep 2007 01:55:58
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 3 Sep, 01:03, "Clive George" <cl...@xxxx-x.fsnet.co.uk > wrote:
> "Roger Merriman" <N...@wodger.demon.co.uk> wrote in message
> Check out Santana's brake testing results, and the brakes SJSC will
"Experienced bike mechanics
tighten a seatpost binder bolt just enough so that they can't rotate
the saddle with one hand."
If I did that I'd be forever re-adjusting my saddle! Can see their
point with carbon posts though.
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Date: 31 Aug 2007 04:13:44
From: Artemisia
Subject: Re: Which Brakes? And What About Lids?
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On 31 ao=FBt, 09:41, Peter Clinch <p.j.cli...@dundee.ac.uk > wrote:
> Something you can happily leave off on a hot day on the Scorpion! :-)
Actually I wear the gloves always, even when not cycling. My balance
is so bad that I have to be constantly grabbing at things - stair
bannisters, bollards, traffic signs - to stay upright when walking in
the street, and I'd rather have the filth accumulate on the gloves
than on my hands. Fortunately they're very washable and fast-drying.
OTOH, what about the head lid on the Scorpion? Carol Hague told me she
never wears a helmet on her Greenspeeds as the kind of head injury one
would get from tipping off an upright just isn't going to happen. But
all the darth websites show the people on the trikes in head-lids, and
there is always my superstitious fear of riding unlidded. I must say I
do find my helmet very sweaty and headache-inducing and as it is now
coming up to three years old, probably needs to be changed anyway. It
would be lovely to dispense with that.
So Dark Siders, do you ride with lids? I'm not trolling and I don't
need justifications or attacks or tables of statistics, I'm just
curious.
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Date: 03 Sep 2007 20:32:11
From: dabac
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta HydraulicDisc?
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Artemisia Wrote:
> ..do you ride with lids? ..I'm just
> curious.
Wearing my helmet has about the same influence on my comfort as wearin
a baseball cap, which I'd probably do anyhow (winds permitting) to kee
the glare out of my eyes.
Even if real advantages are small the "cost" to me using it is eve
smaller, so yes, I i ride lidded
--
dabac
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Date: 31 Aug 2007 12:48:03
From: Mark McNeill
Subject: Re: Which Brakes? And What About Lids?
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Response to Artemisia:
> So Dark Siders, do you ride with lids?
No. I'm even less likely to fall out of a low chair than I am to fall
over when walking or on an upright bike; and those risks are very low
indeed to start with.
--
Mark, UK
"How many things which served us yesterday as articles of faith, are
fables for us today."
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Date: 31 Aug 2007 12:24:50
From: Peter Clinch
Subject: Re: Which Brakes? And What About Lids?
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Artemisia wrote:
> Actually I wear the gloves always, even when not cycling. My balance
> is so bad that I have to be constantly grabbing at things - stair
> bannisters, bollards, traffic signs - to stay upright when walking in
> the street, and I'd rather have the filth accumulate on the gloves
> than on my hands. Fortunately they're very washable and fast-drying.
>
> OTOH, what about the head lid on the Scorpion? Carol Hague told me she
> never wears a helmet on her Greenspeeds as the kind of head injury one
> would get from tipping off an upright just isn't going to happen.
You wear gloves all the time, do you wear a helmet all the time?
If not, note you're in a similar danger of head injury when riding as
when walking, so if you manage when walking without one, you can manage
without one cycling. And on a trike you can't spontaneously fall over
even if you try!
> all the darth websites show the people on the trikes in head-lids
It's more a demographic of the sort of people who ride 'bent trikes.
Greenspeeds are most often photographed in Oz where they're compulsory,
for example. In the UK and US there is a tendency for Serious Cyclists
to wear lids more as they assume it makes good sense (it /does/ until
you actually read the research which shows there's basically no effect
on serious injuries...) and it's Serious Cyclists who invest a small
fortune on 'bent trikes.
> there is always my superstitious fear of riding unlidded.
Then carry a St. Christopher instead.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 31 Aug 2007 12:28:27
From: Roger Merriman
Subject: Re: Which Brakes? And What About Lids?
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Peter Clinch <p.j.clinch@dundee.ac.uk > wrote:
> Artemisia wrote:
>
> > Actually I wear the gloves always, even when not cycling. My balance
> > is so bad that I have to be constantly grabbing at things - stair
> > bannisters, bollards, traffic signs - to stay upright when walking in
> > the street, and I'd rather have the filth accumulate on the gloves
> > than on my hands. Fortunately they're very washable and fast-drying.
> >
> > OTOH, what about the head lid on the Scorpion? Carol Hague told me she
> > never wears a helmet on her Greenspeeds as the kind of head injury one
> > would get from tipping off an upright just isn't going to happen.
>
> You wear gloves all the time, do you wear a helmet all the time?
>
> If not, note you're in a similar danger of head injury when riding as
> when walking, so if you manage when walking without one, you can manage
> without one cycling. And on a trike you can't spontaneously fall over
> even if you try!
that is good point.
>
> > all the darth websites show the people on the trikes in head-lids
>
> It's more a demographic of the sort of people who ride 'bent trikes.
> Greenspeeds are most often photographed in Oz where they're compulsory,
> for example. In the UK and US there is a tendency for Serious Cyclists
> to wear lids more as they assume it makes good sense (it /does/ until
> you actually read the research which shows there's basically no effect
> on serious injuries...) and it's Serious Cyclists who invest a small
> fortune on 'bent trikes.
yes though intrestly folks carry the helmets when on grass etc, often
see folks in bushy park say with the helmet dangling from where ever.
i keep meaning to go and have a go on bent trike, which will happen one
day along with the other things..
>
> > there is always my superstitious fear of riding unlidded.
>
> Then carry a St. Christopher instead.
>
> Pete.
roger
--
www.rogermerriman.com
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Date: 31 Aug 2007 12:18:45
From: Peter Clinch
Subject: Re: Which Brakes? And What About Lids?
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Artemisia wrote:
> So Dark Siders, do you ride with lids?
No, and that's on a bike rather than a trike. I'm not particularly more
likely to head-butt the ground than when I'm walking or using the stairs
(or bits of car if I'm in a car), and I don't wear a lid for walking,
driving or using stairs, so why bother on a bike?
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 30 Aug 2007 23:56:22
From: Artemisia
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 30 ao=FBt, 17:51, David Damerell <damer...@chiark.greenend.org.uk >
wrote:
> I never understood the "big heave" argument. At the end of a day on the
> bike, it's not my fingers that are tired!
Aren't they now? I consider carpal tunnel problems one of the biggest
limiting factors to my cycling day. My hands hurt the blazes when I'm
on tour, and yes, I wear cycling gloves of course.
EFR
Ile de France
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Date: 31 Aug 2007 08:41:24
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Artemisia wrote:
> Aren't they now? I consider carpal tunnel problems one of the biggest
> limiting factors to my cycling day. My hands hurt the blazes when I'm
> on tour, and yes, I wear cycling gloves of course.
Something you can happily leave off on a hot day on the Scorpion! :-)
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 30 Aug 2007 05:51:16
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 30 Aug, 13:02, Peter Clinch <p.j.cli...@dundee.ac.uk > wrote:
> Tom "Johnny Sunset" Sherman wrote:
>
> > Agreed. However, my point is while proper hydraulic disc brakes can be
> > considered the best braking system for a tadpole, the Avid mechanical
> > discs are more than adequate.
>
> But that reduces the argument to stopping power only. Hydraulics give
> you more control over the power because your fingers don't need to do a
> Big heave to get the power. That's why I prefer hydraulics, not
> anything to do with absolute available power: they're just plain nicer
> to use.
Much like a comparison of a car with drum brakes and one with vented 4-
pot discs - the drums will (all too easily) lock up happily, but they
are a lot less pleasant to drive with.
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Date: 30 Aug 2007 15:09:17
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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CoyoteBoy <james.buckle@gmail.com > wrote:
> On 30 Aug, 13:02, Peter Clinch <p.j.cli...@dundee.ac.uk> wrote:
> > Tom "Johnny Sunset" Sherman wrote:
> >
> > > Agreed. However, my point is while proper hydraulic disc brakes can be
> > > considered the best braking system for a tadpole, the Avid mechanical
> > > discs are more than adequate.
> >
> > But that reduces the argument to stopping power only. Hydraulics give
> > you more control over the power because your fingers don't need to do a
> > Big heave to get the power. That's why I prefer hydraulics, not
> > anything to do with absolute available power: they're just plain nicer
> > to use.
>
> Much like a comparison of a car with drum brakes and one with vented 4-
> pot discs - the drums will (all too easily) lock up happily, but they
> are a lot less pleasant to drive with.
quite the hills nr my folks place are steep, as in the 30% range, and
while i can hold safely the old mountain bike going down, even at some
speed i do need some effort, while the new one with disks requires a lot
less effort, back in south west london/surrey the hills have a flatter
profile so neither has a edge really.
roger
--
www.rogermerriman.com
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Date: 30 Aug 2007 03:55:57
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 30 Aug, 11:42, "Clive George" <cl...@xxxx-x.fsnet.co.uk > wrote:
>
> cheers,
> clive
Clive - well summarised! We did rather go off on a tangent didnt we!
In essence, buy the best brake you can afford and make sure its set up
correctly (a decent shop should sort it for you) and you will have few
problems, be they cable or hydro. Any half decent shop should be able
to repair / maintain them for you but they are generally simple enough
to "tweak" on your own - if you have any problems pop back on here and
someone will answer you in 30 seconds - then no doubt we'll go off at
a tangent and argue about the shape of the moon :-)
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Date: 05 Sep 2007 09:33:17
From: Dane Buson
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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In rec.bicycles.misc CoyoteBoy <james.buckle@gmail.com > wrote:
> On 30 Aug, 11:42, "Clive George" <cl...@xxxx-x.fsnet.co.uk> wrote:
>>
>> cheers,
>> clive
>
> Clive - well summarised! We did rather go off on a tangent didnt we!
>
> In essence, buy the best brake you can afford and make sure its set up
> correctly (a decent shop should sort it for you) and you will have few
> problems, be they cable or hydro. Any half decent shop should be able
> to repair / maintain them for you but they are generally simple enough
> to "tweak" on your own - if you have any problems pop back on here and
> someone will answer you in 30 seconds - then no doubt we'll go off at
> a tangent and argue about the shape of the moon :-)
Well, one point. Hasn't the OP had rather a lot of problems with her
local shops being rubbish? If so, I wouldn't trust them to work on
hydraulics since IIRC they are racer (road) oriented. I think the cable
brakes are probably a safer choice in terms of keeping her trike
actually on the road and operating.
--
Dane Buson - sigdane@unixbigots.org
"Drinking through your hair is neither tasty nor nutritious."
-Anonymous
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Date: 30 Aug 2007 03:24:02
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 30 Aug, 10:54, N...@wodger.demon.co.uk (Roger Merriman) wrote:
> Tom "Johnny Sunset" Sherman <sunsetss0...@iinvalid.com> wrote:
> but again locking ones brakes while sounds impressive doesn't stop you
> as fast or as incontrol as braking to just within the limits of the
> tires.
>
> roger
> --www.rogermerriman.com
10% slippage is quoted as best accel and decel tyre slip rate
according to the motorsport boys - im not sure how or why they come to
that conclusion but IIRC its used in F1 so cant be far wrong?
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Date: 30 Aug 2007 01:37:19
From: squeaker
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 30 Aug, 08:35, a...@chiark.greenend.org.uk (Alan Braggins) wrote:
> Some do, but under heavy braking the front wheels have almost all the
> weight on them anyway, so a brake on each front wheel gives you the legally
> required two systems and is as effective and less complicated.
And also remove the possibility of getting said trike sideways if
braking on a curve, which is probably a 'good thing' unless you are
mucking about on a loose surface (which is why KMX fit a rear brake,
AFIK).
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Date: 30 Aug 2007 00:05:39
From: Artemisia
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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Thanks for all the answers, but I'm a bit out of my depth in all this
technical talk.
Might someone explain:
What is brake "bleeding" and why is it necessary (or not)?
What are maggies? HS33s? What kind is Magura Big?
What does "open" and "closed" mean?
What is a rim brake? I don't think any are on offer for my
Scorpion...?
I hope I can delegate any eventual problems and adjustments to my bike
mechanic? Ditto for eventual maintenance? If I buy the brakes as part
of my initial setup, do I still have to do all sorts of adjustments
and setups on my own? See, I don't feel confident to tackle all this
new science and don't have time to take a qualifying degree in bike
maintenance (that my have to wait till I retire!).
On another tack: does a recumbent trike actually have _3_ brakes,
including the one aft? I think the system I'm going for (I mean the
Magura Big) includes an Avid v-brake on the back which also acts as a
parking brake with a velcro strap. Wouldn't that on its own
significantly increase stopping power in relation to 2-wheelers?
I'm thinking I probably will go with the Magura Big setup. The group
is telling me it's worth the extra expense. OTOH I can probably pass
on the DT Swiss suspension thingey and make do with the Busch & Muller
bottle dynamo with standlight, rather than the SON hub dynamo.
Saturday I go speak to Darth Delano at Rando-cycles. I hope he too may
have some advice for me.
Thanks to all for the lively and informative discussion.
EFR
Ile de France
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Date: 30 Aug 2007 11:42:55
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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"Artemisia" <e.roselli@free.fr > wrote in message
news:1188457539.325873.205490@g4g2000hsf.googlegroups.com...
> Thanks for all the answers, but I'm a bit out of my depth in all this
> technical talk.
Oops, sorry, most of it wasn't at all relevant to your original request.
> Might someone explain:
>
> What is brake "bleeding" and why is it necessary (or not)?
Hydraulic systems work using fluids which are pretty much incompressible.
Air is the opposite - if you increase the pressure, a given lump of air gets
smaller - which you can see with a bike pump. If you get air in the brake
system, it won't work nearly as well. Bleeding is the process of getting rid
of air, which basically involves pushing fluid through until there are no
more bubbles.
And if you've got it set up right for you, you won't ever need to do it.
> What are maggies? HS33s? What kind is Magura Big?
"maggie" is I believe short for Magura, HS33 are their rim brakes, so
irrelevant to your application.
> What does "open" and "closed" mean?
A closed system has a piston at each end of a pipe. Move the piston at one
end, it will move at the other - conventional hydraulics there. However if
you warm the fluid up, it will expand, and the two pistons will move apart -
which may not be a good thing.
An open system is more like what a car has. There's a small reservoir at the
top, and when the brakes are off, the pipe is connected to that, allowing
expansion and contraction of fluid (and automatic adjustment of pads).
> What is a rim brake? I don't think any are on offer for my
> Scorpion...?
A rim brake is like what you have on normal bikes - the pads are applied to
the rim.
> I hope I can delegate any eventual problems and adjustments to my bike
> mechanic? Ditto for eventual maintenance? If I buy the brakes as part
> of my initial setup, do I still have to do all sorts of adjustments
> and setups on my own? See, I don't feel confident to tackle all this
> new science and don't have time to take a qualifying degree in bike
> maintenance (that my have to wait till I retire!).
Yes, you should be able to.
cheers,
clive
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Date: 30 Aug 2007 09:35:33
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Artemisia wrote:
> Might someone explain:
Alan pretty much has, but a couple of extra notes...
> What is brake "bleeding" and why is it necessary (or not)?
While this isn't necessary with mechanical cables as there's no fluid to
bleed, mechanical cables have their own problems and in practice need to
be replaced periodically too, probably more than hydraulics need bleeding.
> What are maggies? HS33s? What kind is Magura Big?
Note that HS-33s aren't relevant on the Scorpion as it'll be discs only,
so if it's on the price list for a Scorpion it will be a disc. HS-33s
use hydraulics rather than cables which is why they've been brought up,
to compare general characteristics of hydraulic and mechanical setups.
> I hope I can delegate any eventual problems and adjustments to my bike
> mechanic? Ditto for eventual maintenance? If I buy the brakes as part
> of my initial setup, do I still have to do all sorts of adjustments
> and setups on my own? See, I don't feel confident to tackle all this
> new science and don't have time to take a qualifying degree in bike
> maintenance (that my have to wait till I retire!).
That's why you're paying a shop, so you don't have to worry. Brakes
aren't set up in a personal way like suspension, which is ideally
something you should be able to tune yourself if you've bought a tunable
setup like the DT-Swiss on offer.
> On another tack: does a recumbent trike actually have _3_ brakes,
> including the one aft? I think the system I'm going for (I mean the
> Magura Big) includes an Avid v-brake on the back which also acts as a
> parking brake with a velcro strap. Wouldn't that on its own
> significantly increase stopping power in relation to 2-wheelers?
The back brake is really just there as a parking brake. It won't have
too much effect on your real stopping power which will be taken up
front, because as soon as you slam on the anchors all the weight will be
on the front wheels and all you'll get by braking at the back is locking
the wheel and skidding.
I think you'll be happily surprised about how much stopping power you
get on a low recumbent trike with properly specified brakes.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 30 Aug 2007 11:49:31
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Peter Clinch" <p.j.clinch@dundee.ac.uk > wrote in message
news:5jndppFe99rU1@mid.individual.net...
>> On another tack: does a recumbent trike actually have _3_ brakes,
>> including the one aft? I think the system I'm going for (I mean the
>> Magura Big) includes an Avid v-brake on the back which also acts as a
>> parking brake with a velcro strap. Wouldn't that on its own
>> significantly increase stopping power in relation to 2-wheelers?
>
> The back brake is really just there as a parking brake. It won't have
> too much effect on your real stopping power which will be taken up
> front, because as soon as you slam on the anchors all the weight will be
> on the front wheels and all you'll get by braking at the back is locking
> the wheel and skidding.
> I think you'll be happily surprised about how much stopping power you
> get on a low recumbent trike with properly specified brakes.
I suppose I could mention here that I never missed having a back brake on
the greenspeed tandem we had for a while. The two front disks gave plenty of
stopping power.
cheers,
clive
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Date: 30 Aug 2007 08:35:06
From: Alan Braggins
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
In article <1188457539.325873.205490@g4g2000hsf.googlegroups.com >, Artemisia wrote:
>Thanks for all the answers, but I'm a bit out of my depth in all this
>technical talk.
>
>Might someone explain:
>
>What is brake "bleeding" and why is it necessary (or not)?
http://en.wikipedia.org/wiki/Brake_bleeding
>What are maggies?
Magura brakes.
> HS33s?
A model of Magura rim brake
> What kind is Magura Big?
Disc.
>What does "open" and "closed" mean?
Whether the reservoir of hydraulic fluid in the brake system is open
to the atmosphere or has an airtight seal.
>What is a rim brake?
A brake where the pads act on the rim of the wheel - a "normal" bike
brake that isn't a hub or disc brake.
>I hope I can delegate any eventual problems and adjustments to my bike
>mechanic? Ditto for eventual maintenance?
Yes, assuming a competent mechanic. A decent shop will sort the initial
setup for you too.
>On another tack: does a recumbent trike actually have _3_ brakes,
>including the one aft?
Some do, but under heavy braking the front wheels have almost all the
weight on them anyway, so a brake on each front wheel gives you the legally
required two systems and is as effective and less complicated.
|
| |
Date: 29 Aug 2007 15:33:46
From: squeaker
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
If you do go Avid mechanical, go BB7 not BB5. The differences are
deeper than 'no outer pad adjuster', IMHO.
|
| |
Date: 29 Aug 2007 12:41:57
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 29 Aug, 19:24, "Clive George" <cl...@xxxx-x.fsnet.co.uk > wrote:
> "coyoteboy" <coyotebo...@hotmail.com> wrote in message
>
> news:Q8-dnavnILOhKkjbnZ2dneKdnZydnZ2d@bt.com...
>
> > Many disc manufacturers use mineral oil like maggies so it doesnt absorb
> > water, but even so the DOT based fluids never reach the sort of heat
> > required to "wet boil" in anything other than extreme downhill conditions.
>
> Remember I'm using ours on a tandem...
>
> > I just dont understand where this idea that hydro discs are "high
> > maintenance" comes from.
>
> I'm not sure where you get it from either. I'm talking about relative to the
> rim brakes.
You are suggesting that hydro discs need frequent maintenance and are
more complex than the rims - im suggesting they arent.
> But if you consider this experience -
>
> Rim brakes : Worked out of the box, zero maintenance required of the
> internals in 10 years
>
> Discs : Need bedding in, needed bleeding to make the back brake work,
> pistons misbehaving a little in 2 years. And of course there's the way the
> disc pads can't cope with oil on them :-( (got sintered now, so you just
> need to let the smoke out to fix this - but the rims don't suffer in this
> way)
It takes a short ride to bed a disc - 10-20 miles - if it takes longer
you have the caliper mis-aligned. Maggies also need you to carefully
align the pads or you get squeeks and the pads wearing unevenly. Why
would you have to bleed the rear? Presumably to fit to the frame- the
same with any hydro brake such as HS33? Why (and how) are the pistons
misbehaving - this again suggests you have the caliper misaligned to
start with - the pads pushing at odd angles tend to get jammed and not
retract well? This is totally contrary to my experience with well set
up discs, but i did get to practice on a few customers bikes before I
could afford my own! No, pads cant cope with oil on them, but then
maggie pads cant cope well in mud and ice. If you get oil on them then
thats carelessness, not the brake at fault - at least when out on the
trail a disc will work when drowned in mud and ice (better in most
cases) while maggies tend to tail off a little, especially at speed
again. If you ride in any real snow you'll find maggies get a nice
smooth layer of snow-ice packed onto the rim eventually - this isnt
fun - discs remain hot and prevent this.
|
| |
Date: 29 Aug 2007 12:33:14
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 29 Aug, 19:13, "Clive George" <cl...@xxxx-x.fsnet.co.uk > wrote:
> "coyoteboy" <coyotebo...@hotmail.com> wrote in message
> Indeed. If you get your brakes hot, closed doesn't work. And I got that on
> hardly any hill at all. But then this was on a tandem.
Tandems are a tad of an issue being essentially twice the energy being
dissipated as the brake was designed for. Must say I've never worked
on them but I cant see any reason why the mechanics of the work is any
different.
> Hmm. I'm guessing you've never bled a set of Hopes then. I've done one end
> of ours, and it was a right pain, even with the bleeding kit.
Yup, hopes were my first ever disc, never had a problem, never had the
bleed kit. I've shortened hoses on them a few times between frame/fork
changes on other peoples bikes and I didnt find bleeding them an issue
at all? Certainly easier than magura HS33s. But then I'm used to
bleeding the brakes on my car - maybe that helps? I didnt think it
could possibly be considered a difficult task?
> One problem is them using DOT brake fluid. I _hate_ DOT brake fluid. (My car
> doesn't use it either...). It needs changing in a way that the mineral oil
> doesn't - 2 years, not 10.
No it doesnt - this is where you are mistaken. It requires changing
only if you are going to overheat it - recommendations of 2 years are
set by car standards (which were thought up decades ago when brake
systems were considerably more agricultural and allowed moisture
absorbtion easily) and our brakes do not reach the heat of a car
caliper (though, of course, a tandem may get closer). Even on a DH run
in the alps myDH4 /calipers/ rarely got hot enough to burn with me
(15stone, the bike at 40lbs and speeds of 40mph). The wet boil temp of
DOT4 is 155 degrees C - if you get your calipers to anywhere near 155C
i bow down to your superior braking! (or pass you on the way down :-),
most braking is un-necessary if you pick the right lines) I've yet to
hear of anyone boiling fluid in a bike brake - fading organic pads due
to outgassing, yes (solved by choosing a correct pad material from the
start). On a car - yes. The primary reason for bleeding DOT fluids is
to remove the fluid which has absorbed water (hence the wet boil
temps) and return "dry" fluid which boils at 240C. I actually change
out my fluid for DOT5.1 if I change the cable routing etc and have to
bleed, much the same as I'd change the cables on a cable brake or
change the fluid on the maggies.
> I guess if I had Magura disks, some of my complaints may go away. (Shimano's
> a no-no based on the use we give them).
Yes, I agree you wouldnt want shimano discs on a tandem - too
lightweight IME.
> The reason I say the discs aren't fit and forget in the same way as the
> magura rims is that I have had to do this sort of crap on them, whereas the
> rims have been sealed since I fitted them 10 years ago, and have never given
> any problems.
Why did you have to bleed it? It just isnt necessary. And as
mentioned, it couldnt be an easier task to blow through new fluid, not
like when you get really bad bubbles in and have to get shut of them
too. I'll do a youtube vid soon, maybe I have some magic technique I
didnt know was magic?
> There is another question though : is it worth the hassle? And the answer
> for the MTB tandem is definitely yes. Can't tell for the road tandem since
> nobody makes suitable hydraulic discs...
I'm missing where the hassle comes in TBH - which was my point from
the start - hydros are the most fit and forget items on any bike I've
owned or maintained!
|
| | |
Date: 29 Aug 2007 22:06:48
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"CoyoteBoy" <james.buckle@gmail.com > wrote in message
news:1188415994.932636.279250@r29g2000hsg.googlegroups.com...
> On 29 Aug, 19:13, "Clive George" <cl...@xxxx-x.fsnet.co.uk> wrote:
>> "coyoteboy" <coyotebo...@hotmail.com> wrote in message
>> Indeed. If you get your brakes hot, closed doesn't work. And I got that
>> on
>> hardly any hill at all. But then this was on a tandem.
>
> Tandems are a tad of an issue being essentially twice the energy being
> dissipated as the brake was designed for. Must say I've never worked
> on them but I cant see any reason why the mechanics of the work is any
> different.
No, the mechanics are the same.
>> Hmm. I'm guessing you've never bled a set of Hopes then. I've done one
>> end
>> of ours, and it was a right pain, even with the bleeding kit.
>
> Yup, hopes were my first ever disc, never had a problem, never had the
> bleed kit. I've shortened hoses on them a few times between frame/fork
> changes on other peoples bikes and I didnt find bleeding them an issue
> at all? Certainly easier than magura HS33s. But then I'm used to
> bleeding the brakes on my car - maybe that helps? I didnt think it
> could possibly be considered a difficult task?
Maybe the mono levers are more of a pain then. Certainly the bits which are
similar to a car were no problem whatsoever - but the reserviour is
significantly more hassle, being all tiny and fiddly and having no spare
capacity.
>> One problem is them using DOT brake fluid. I _hate_ DOT brake fluid. (My
>> car
>> doesn't use it either...). It needs changing in a way that the mineral
>> oil
>> doesn't - 2 years, not 10.
>
> No it doesnt - this is where you are mistaken. It requires changing
> only if you are going to overheat it
Or if it gets wet. The mineral oil I have sitting around won't suffer this -
but the container of DOT fluid may well do :-(
> The wet boil temp of
> DOT4 is 155 degrees C - if you get your calipers to anywhere near 155C
> i bow down to your superior braking! (or pass you on the way down :-),
Probably both. I'm not a fantastically confident descender, so will use the
brakes, and as you noticed I can put twice the energy into them. (Actually
it's potentially more than that, since I can't endo...)
>> The reason I say the discs aren't fit and forget in the same way as the
>> magura rims is that I have had to do this sort of crap on them, whereas
>> the
>> rims have been sealed since I fitted them 10 years ago, and have never
>> given
>> any problems.
>
> Why did you have to bleed it?
Because there was air in it. I think the people who put the tandem-length
pipe on it got it wrong - that was Hope BTW.
> It just isnt necessary.
Except it was...
> And as
> mentioned, it couldnt be an easier task to blow through new fluid, not
> like when you get really bad bubbles in and have to get shut of them
> too.
Like I did?
>> There is another question though : is it worth the hassle? And the answer
>> for the MTB tandem is definitely yes. Can't tell for the road tandem
>> since
>> nobody makes suitable hydraulic discs...
>
> I'm missing where the hassle comes in TBH - which was my point from
> the start - hydros are the most fit and forget items on any bike I've
> owned or maintained!
> If you get oil on them then thats carelessness, not the brake at fault
Actually, it's the fork air seal failing and dumping the oil on the brakes.
The sensitivity of the brakes to oil is a definite downside - with care, the
problem can be avoided, but I'm sure you'd agree the it would be better if
it wasn't there in the first place.
I think my discs are set up fairly well - they're definitely straight (I
spent a while getting that right when first installing them, and I'm not
completely mechanically inept.)
cheers,
clive
|
| |
Date: 29 Aug 2007 12:12:17
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 29 Aug, 19:19, Paul Boyd <use...@abcd.invalid > wrote:
> On 29/08/2007 19:58, coyoteboy said,
> OK - I didn't realise the first bit, but the second bit? That's why
> Shimano have the bladder in the lever - so that as the fluid expands the
> air in the bladder compresses to compensate. Perhaps I'm
> misunderstanding what is meant by a closed system.
Yup, i think thats where the confusion comes in - a closed system is
one where the entire volume of the fluid is under pressure when the
lever is squozed :) An open system has a reservoir (be it a bladder or
a cup etc). A closed system is like the magura HS33 - there is no
reservoir meaning if the system heats enough to make the fluid expand
you have to back off either the lever position or a separate adjuster
(just another piston essentially) to stop the brakes binding. The open
system relies on seal flex to pull the pistons back and pushes spare
fluid back into the reservoir, but as the fluid heats up it gets
pushed back into the reservoir naturally and doesnt affect the piston
position.
> Surely that's the same for any system, except I assume you mean take the
> top off the lever?
Yes, it is for any hydro system (I wasnt disagreeing with your post, I
was confirming). Maggies (HS33) are harder than most to bleed when
needed due to the fact that they are closed and you need to remove
every last bubble from the lever to prevent spongeyness - this was the
main problem I had brought back to me time and time again by HS33
owners who had had a go at bleeding.
J
|
| | |
Date: 29 Aug 2007 20:41:40
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
On 29/08/2007 20:12, CoyoteBoy said,
> Yup, i think thats where the confusion comes in - a closed system is
> one where the entire volume of the fluid is under pressure when the
> lever is squozed :) An open system has a reservoir (be it a bladder or
> a cup etc).
I was totally confused, wasn't I? :-)
--
Paul Boyd
http://www.paul-boyd.co.uk/
|
| |
Date: 29 Aug 2007 17:40:00
From: Marz
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Aug 29, 12:21 pm, Peter Clinch <p.j.cli...@dundee.ac.uk > wrote:
> Marz wrote:
> > Sounds like your consensus views are coming from folks who can't
> > afford hydraulic brakes and therefore slag 'em off.
>
> I suspect it's more the owner moves to cable discs from an older
> rim setup with fairly old cables and immediately thinks "bloody
> 'ell, these are a lot better!", and of course they are. Beyond
> that one is inclined to think "but hey, I can lock the wheels with
> these so I've got all the power I want, what more do you need?".
> That's what I thought when I decided to save money on not getting
> HS-33s going through the option list on the Streetmachine, and I
> was happy with mechanical Vs on it for quite a while.
> But I got a bit of Bling Envy when Roos bought her 'bent so I
> treated mine to a brake upgrade. And wished I'd bought the
> hydraulics in the first place. The feel and control is just
> /sooooooooo/ much better.
>
> Pete.
> --
> Peter Clinch Medical Physics IT Officer
> Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
> Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
> net p.j.cli...@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
I still miss my HS-33s on my mountain bike, which to be honest, were
as good (if not better) than the hayes disks I run today. It was just
that when things got muddy the HS-33s could get bunged up pretty
quickly and collect enough mud to stop the wheels.
|
| |
Date: 29 Aug 2007 16:54:52
From: Marz
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Aug 28, 1:14 pm, Artemisia <nos...@free.fr > wrote:
> Now I've been reading up on the competition, and have become confused.
> The Avid mechanical brakes are what come as standard. I've done some
> googling on these and have found the most incredibly consistent series
> of rave reviews. The consensus out there seems to be - people who fork
> out extra for hydraulic discs are plain stupid or misguided, the Avids
> are so good as to be unbeatable on function at a much lower price and
> much easier maintenance.
>
Sounds like your consensus views are coming from folks who can't
afford hydraulic brakes and therefore slag 'em off. Hydraulic brakes
offer better control and braking consistency than mechanical brakes
and if set up properly in the first place,require less maintainence.
The only plus side to mechanicals could be the ability to fix them out
in the field if something breaks.
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Date: 29 Aug 2007 23:41:43
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Marz <marzjennings@gmail.com >:
> Sounds like your consensus views are coming from folks who can't
>afford hydraulic brakes and therefore slag 'em off.
Lesson one, children; why ad hominems are a logical fallacy.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is First Sunday, August - a weekend.
|
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Date: 29 Aug 2007 18:21:11
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Marz wrote:
> Sounds like your consensus views are coming from folks who can't
> afford hydraulic brakes and therefore slag 'em off.
I suspect it's more the owner moves to cable discs from an older
rim setup with fairly old cables and immediately thinks "bloody
'ell, these are a lot better!", and of course they are. Beyond
that one is inclined to think "but hey, I can lock the wheels with
these so I've got all the power I want, what more do you need?".
That's what I thought when I decided to save money on not getting
HS-33s going through the option list on the Streetmachine, and I
was happy with mechanical Vs on it for quite a while.
But I got a bit of Bling Envy when Roos bought her 'bent so I
treated mine to a brake upgrade. And wished I'd bought the
hydraulics in the first place. The feel and control is just
/sooooooooo/ much better.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
|
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Date: 30 Aug 2007 10:08:30
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Peter Clinch said the following on 29/08/2007 18:21:
> The feel and control is just /sooooooooo/ much better.
That's really the crux of the matter. Any brake should be able to lock
up your wheels, therefore provide more than enough raw stopping power,
but it's how you can control that power that makes the difference.
--
Paul Boyd
http://www.paul-boyd.co.uk/
|
| | | | |
Date: 30 Aug 2007 10:39:24
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Paul Boyd wrote:
> Peter Clinch said the following on 29/08/2007 18:21:
>> The feel and control is just /sooooooooo/ much better.
>
> That's really the crux of the matter. Any brake should be able to lock
> up your wheels, therefore provide more than enough raw stopping power,
> but it's how you can control that power that makes the difference.
Agreed, and IME there was a very big difference between reading about it
in theory and actually experiencing it.
I went from sceptic feeling there wasn't really anything wrong with my
brakes as they were to "Oh! *Now* I see what the point is, I think I'll
be getting some of these!" over the course of a day's riding on an
otherwise rather unimpressive demo bike.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
|
| | | | | |
Date: 30 Aug 2007 15:09:17
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Peter Clinch <p.j.clinch@dundee.ac.uk > wrote:
> Paul Boyd wrote:
> > Peter Clinch said the following on 29/08/2007 18:21:
> >> The feel and control is just /sooooooooo/ much better.
> >
> > That's really the crux of the matter. Any brake should be able to lock
> > up your wheels, therefore provide more than enough raw stopping power,
> > but it's how you can control that power that makes the difference.
>
> Agreed, and IME there was a very big difference between reading about it
> in theory and actually experiencing it.
>
> I went from sceptic feeling there wasn't really anything wrong with my
> brakes as they were to "Oh! *Now* I see what the point is, I think I'll
> be getting some of these!" over the course of a day's riding on an
> otherwise rather unimpressive demo bike.
>
> Pete.
hills do it as well, taking the new bike down some of the hills that
where real forearm pumpers before, now i could just glide down.
roger
--
www.rogermerriman.com
|
| |
Date: 29 Aug 2007 09:28:08
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 29 Aug, 15:16, "Clive George" <cl...@xxxx-x.fsnet.co.uk > wrote:
> "Peter Clinch" <p.j.cli...@dundee.ac.uk> wrote in message
>
> news:5jlcgfF5p4oU2@mid.individual.net...
>
> > CoyoteBoy wrote:
>
> >> I'm fairly sure its the cable stretch and binding alone that causes it
> >> - with hydro it just releases the pressure and hence force, with
> >> cables you have to overcome friction and stretch as well.
>
> > I agree. Having recently re-cabled my Brompton's brakes and changed it
> > from potential death trap to bike with fair brakes I'm very aware of
> > just how much cables can degrade. But the hydrualics on the 'bent are
> > still beautifully responsive 3 years after putting them on
>
> If they behave as well as those on our tandem, they'll still be good 10
> years after fitting.
>
> But the magura rim brakes are closed, and the tolerances can be much
> greater - there's loads of room for eg pad movement. With an open disc
> system, you introduce the joy of eg bleeding the damn things, and there's
> less margin for error. When I manage to let the smoke out of the hydraulic
> discs on the MTB tandem, they work very well - but the rim brakes are
> fit-and-forget in the way the discs distinctly aren't :-(
>
> (still probably wouldn't have cables though)
>
> cheers,
> clive
What the hell have you been doing to your discs? Why would you need to
bleed you discs unless you've damaged them? What error do you need
margin for? I found HS33s lose their bite when you run low on pad and
have to adjust them out to meet the rim. Plus they are a pain in the
arse when you buckle a rim which is far more frequent than buckling a
rotor?
|
| |
Date: 29 Aug 2007 06:55:29
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 29 Aug, 09:57, Peter Clinch <p.j.cli...@dundee.ac.uk > wrote:
> roger merriman wrote:
> > Thing is though that locking the wheels is one thing, stopping fast
> > and safely is another, my cheap hybrid can lock it's wheels, but i
> > would regard is brakes as poor, in that it wouldn't stop in hurry at
> > speed, while my moutain bikes will, which considering the rubber on
> > the road i'd probably struggle to lock wheels up.
>
> Indeed. And this is where hydraulics are better IMHO, as they let you
> have high power combined with very sensitive fingertip control.
I'm fairly sure its the cable stretch and binding alone that causes it
- with hydro it just releases the pressure and hence force, with
cables you have to overcome friction and stretch as well.
|
| | |
Date: 29 Aug 2007 15:01:16
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
CoyoteBoy wrote:
> I'm fairly sure its the cable stretch and binding alone that causes it
> - with hydro it just releases the pressure and hence force, with
> cables you have to overcome friction and stretch as well.
I agree. Having recently re-cabled my Brompton's brakes and changed it
from potential death trap to bike with fair brakes I'm very aware of
just how much cables can degrade. But the hydrualics on the 'bent are
still beautifully responsive 3 years after putting them on
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
|
| | | |
Date: 29 Aug 2007 15:16:32
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Peter Clinch" <p.j.clinch@dundee.ac.uk > wrote in message
news:5jlcgfF5p4oU2@mid.individual.net...
> CoyoteBoy wrote:
>
>> I'm fairly sure its the cable stretch and binding alone that causes it
>> - with hydro it just releases the pressure and hence force, with
>> cables you have to overcome friction and stretch as well.
>
> I agree. Having recently re-cabled my Brompton's brakes and changed it
> from potential death trap to bike with fair brakes I'm very aware of
> just how much cables can degrade. But the hydrualics on the 'bent are
> still beautifully responsive 3 years after putting them on
If they behave as well as those on our tandem, they'll still be good 10
years after fitting.
But the magura rim brakes are closed, and the tolerances can be much
greater - there's loads of room for eg pad movement. With an open disc
system, you introduce the joy of eg bleeding the damn things, and there's
less margin for error. When I manage to let the smoke out of the hydraulic
discs on the MTB tandem, they work very well - but the rim brakes are
fit-and-forget in the way the discs distinctly aren't :-(
(still probably wouldn't have cables though)
cheers,
clive
|
| | | | |
Date: 29 Aug 2007 17:50:26
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Clive George said the following on 29/08/2007 15:16:
> but the rim
> brakes are fit-and-forget in the way the discs distinctly aren't :-(
Nothing against your opinion personally, but I've seen this sort of view
expressed before and I'm a bit puzzled by it. I fitted my hydraulic
disc brakes ages ago, and I've forgotten about them ever since. With
hydraulic disc brakes there's far less to go wrong than with any cable
brakes (can you even still get open systems?), and they just keep
working. They may need to be bled once every so often, but cables need
maintenance more than once every so often. All brakes need pads/blocks
replaced periodically, so I'm genuinely interested in why you think
discs aren't "fit and forget".
> (still probably wouldn't have cables though)
Agreed. I have had cables, then hydraulics, and the "feel" of the two
is worlds apart.
--
Paul Boyd
http://www.paul-boyd.co.uk/
|
| | | | | |
Date: 30 Aug 2007 16:16:15
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Paul Boyd <usenet.is.worse@plusnet > wrote:
> Clive George said the following on 29/08/2007 15:16:
>
> > but the rim
> > brakes are fit-and-forget in the way the discs distinctly aren't :-(
>
> Nothing against your opinion personally, but I've seen this sort of view
> expressed before and I'm a bit puzzled by it. I fitted my hydraulic
> disc brakes ages ago, and I've forgotten about them ever since. With
> hydraulic disc brakes there's far less to go wrong than with any cable
> brakes (can you even still get open systems?), and they just keep
> working. They may need to be bled once every so often, but cables need
> maintenance more than once every so often. All brakes need pads/blocks
> replaced periodically, so I'm genuinely interested in why you think
> discs aren't "fit and forget".
>
i love the disks on my new bike but reliable they have not been, jamed
on a few times, it's probably the use, or rather lack of, the bike has
seen the inside of 3 sheds but very little mud to play with.
> > (still probably wouldn't have cables though)
>
> Agreed. I have had cables, then hydraulics, and the "feel" of the two
> is worlds apart.
roger
--
www.rogermerriman.com
|
| | | | | |
Date: 29 Aug 2007 19:58:27
From: coyoteboy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Paul Boyd wrote:
>(can you even still get open systems?), and they just keep
Lots of the top end systems are open - its how they get automatic pad
wear adjustment. Certainly most of the systems I've seen on the trail
have been open - closed just makes no sense - need to adjust pad on the
fly and back it off if you heat the caliper up.
> working. They may need to be bled once every so often, but cables need
> maintenance more than once every so often. All brakes need pads/blocks
> replaced periodically, so I'm genuinely interested in why you think
> discs aren't "fit and forget".
And if you want to bleed them, which isnt really needed for a decade at
a time, you just lob a piece of hose on the nipple, take the top off the
caliper and squeeze, undo, tighten, release a few times and its done -
not even as complex as replacing a cable!
|
| | | | | | |
Date: 29 Aug 2007 19:19:49
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
On 29/08/2007 19:58, coyoteboy said,
> Lots of the top end systems are open - its how they get automatic pad
> wear adjustment. Certainly most of the systems I've seen on the trail
> have been open - closed just makes no sense - need to adjust pad on the
> fly and back it off if you heat the caliper up.
OK - I didn't realise the first bit, but the second bit? That's why
Shimano have the bladder in the lever - so that as the fluid expands the
air in the bladder compresses to compensate. Perhaps I'm
misunderstanding what is meant by a closed system.
> And if you want to bleed them, which isnt really needed for a decade at
> a time, you just lob a piece of hose on the nipple, take the top off the
> caliper and squeeze, undo, tighten, release a few times and its done -
> not even as complex as replacing a cable!
Surely that's the same for any system, except I assume you mean take the
top off the lever?
--
Paul Boyd
http://www.paul-boyd.co.uk/
|
| | | | | | |
Date: 29 Aug 2007 19:13:11
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"coyoteboy" <coyoteboyuk@hotmail.com > wrote in message
news:Xdqdnct89N9TLkjbnZ2dnUVZ8surnZ2d@bt.com...
> Paul Boyd wrote:
>>(can you even still get open systems?), and they just keep
>
> Lots of the top end systems are open - its how they get automatic pad wear
> adjustment. Certainly most of the systems I've seen on the trail have been
> open - closed just makes no sense - need to adjust pad on the fly and back
> it off if you heat the caliper up.
Indeed. If you get your brakes hot, closed doesn't work. And I got that on
hardly any hill at all. But then this was on a tandem.
>> working. They may need to be bled once every so often, but cables need
>> maintenance more than once every so often. All brakes need pads/blocks
>> replaced periodically, so I'm genuinely interested in why you think discs
>> aren't "fit and forget".
>
> And if you want to bleed them, which isnt really needed for a decade at a
> time, you just lob a piece of hose on the nipple, take the top off the
> caliper and squeeze, undo, tighten, release a few times and its done - not
> even as complex as replacing a cable!
Hmm. I'm guessing you've never bled a set of Hopes then. I've done one end
of ours, and it was a right pain, even with the bleeding kit.
One problem is them using DOT brake fluid. I _hate_ DOT brake fluid. (My car
doesn't use it either...). It needs changing in a way that the mineral oil
doesn't - 2 years, not 10.
I guess if I had Magura disks, some of my complaints may go away. (Shimano's
a no-no based on the use we give them).
The reason I say the discs aren't fit and forget in the same way as the
magura rims is that I have had to do this sort of crap on them, whereas the
rims have been sealed since I fitted them 10 years ago, and have never given
any problems.
There is another question though : is it worth the hassle? And the answer
for the MTB tandem is definitely yes. Can't tell for the road tandem since
nobody makes suitable hydraulic discs...
(Paul - does this answer your question too?)
cheers,
clive
|
| | | | | |
Date: 29 Aug 2007 18:18:38
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Paul Boyd" <usenet.is.worse@plusnet > wrote in message
news:13db90sobf3n8f4@corp.supernews.com...
> Clive George said the following on 29/08/2007 15:16:
>
>> but the rim brakes are fit-and-forget in the way the discs distinctly
>> aren't :-(
>
> Nothing against your opinion personally, but I've seen this sort of view
> expressed before and I'm a bit puzzled by it.
That's because you carefully snipped the bit where I said "magura rim
brakes". You do know that magura don't make cable brakes, don't you? Their
hydraulic rim brakes have been around for ages now.
> I fitted my hydraulic disc brakes ages ago, and I've forgotten about them
> ever since.
...
> They may need to be bled once every so often
That isn't "forgotten about them". I've never opened the rim brake
internals - and they are 10 years old now.
> All brakes need pads/blocks replaced periodically, so I'm genuinely
> interested in why you think discs aren't "fit and forget".
Compared to the magura rim brakes, they aren't IME. That's it.
cheers,
clive
|
| | | | | | |
Date: 29 Aug 2007 20:13:05
From: coyoteboy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Clive George wrote:
> That isn't "forgotten about them". I've never opened the rim brake
> internals - and they are 10 years old now.
I've replaced the magura blood after 4 years (just because I got some
for free) and it makes definite difference to pad movement feel. But
then my other HS33s had their oil replaced with chip oil when i ripped
the hose out of them on holiday and that works just as well to this day.
I think the point is that there is no need to bleed a disc, as there
isnt with a HS33. Many disc manufacturers use mineral oil like maggies
so it doesnt absorb water, but even so the DOT based fluids never reach
the sort of heat required to "wet boil" in anything other than extreme
downhill conditions. People often bleed hydro discs because they assume
they "should" - there is no need.
>> All brakes need pads/blocks replaced periodically, so I'm genuinely
>> interested in why you think discs aren't "fit and forget".
>
> Compared to the magura rim brakes, they aren't IME. That's it.
IME (I "maintain" 2 sets of HS33s - one pair of Raceline D and one
newer, 2 hope DH4s, 1 hope mini, 1 hope mini mono, a pair of louise FRs
and have direct contact with owners of cheapo cable and shimano XT discs
and have plain old Vs on the old machine that gets no use these days)
they are comparable to maggies - in fact less effort required, and less
problems with rim damage effecting them. The worst thing is the
occasional bouts of squeel, but then the HS33s get that with the wet
weather pads from time to time too. I managed to melt a set of HS33 pads
to the rim in the alps (DH course) and have blue'd the rotors on the
DH4s and mini several times. I just dont understand where this idea that
hydro discs are "high maintenance" comes from. I'd not replace my
maguras on my trials bike because the discs just dont bite as
aggressively at low speed, but then the maggies dont control as well at
high speed so I wouldnt use them on my MTB anymore - even with the
maggies I've run into the back of my brother (DH4s) on numerous
occasions due to the poorer high-speed braking (which is still
blisteringly good IMO).
|
| | | | | | | |
Date: 29 Aug 2007 19:24:52
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"coyoteboy" <coyoteboyuk@hotmail.com > wrote in message
news:Q8-dnavnILOhKkjbnZ2dneKdnZydnZ2d@bt.com...
> Many disc manufacturers use mineral oil like maggies so it doesnt absorb
> water, but even so the DOT based fluids never reach the sort of heat
> required to "wet boil" in anything other than extreme downhill conditions.
Remember I'm using ours on a tandem...
> I just dont understand where this idea that hydro discs are "high
> maintenance" comes from.
I'm not sure where you get it from either. I'm talking about relative to the
rim brakes.
But if you consider this experience -
Rim brakes : Worked out of the box, zero maintenance required of the
internals in 10 years
Discs : Need bedding in, needed bleeding to make the back brake work,
pistons misbehaving a little in 2 years. And of course there's the way the
disc pads can't cope with oil on them :-( (got sintered now, so you just
need to let the smoke out to fix this - but the rims don't suffer in this
way)
them you might understand where I'm coming from.
cheers,
clive
|
| | | | | | |
Date: 29 Aug 2007 18:56:43
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
On 29/08/2007 18:18, Clive George said,
> That's because you carefully snipped the bit where I said "magura rim
> brakes". You do know that magura don't make cable brakes, don't you?
> Their hydraulic rim brakes have been around for ages now.
Are we talking at crossed purposes here? You said "but the rim brakes
are fit-and-forget in the way the discs distinctly aren't". I know you
were talking about the Magura rim brakes as being fit and forget - that
wasn't in question, but you said that disc brakes aren't. I was just
curious as to why you thought disc brakes weren't fit and forget - if
you haven't had to touch them in 10 years (apart from pads, presumably)
then you've now partly explained it.
However, I haven't had hydraulic disc brakes for 10 years, so I can't
comment on whether I would actually need to bleed them every so often or
not - I haven't had to in 12 months. I've just heard that they should
be bled every couple of years. Like Magura though, Shimano use a closed
system filled with mineral oil, so in theory they should never need
bleeding, and my POV is that I'll only bleed them if they get spongy.
To me, that is fit and forget, but I'll let you know in 9 years time :-)
--
Paul Boyd
http://www.paul-boyd.co.uk/
|
| |
Date: 29 Aug 2007 01:52:54
From: roger merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 29 Aug, 05:03, "Tom \"Johnny Sunset\" Sherman"
<sunsetss0...@iinvalid.com > wrote:
> Artemisia wrote:
> > I've been assuming all along that the brakes I would get on my new HPV
> > Scorpion would be the Magura Big Hydraulic disc. I made this assumption
> > because in the _Greenspeed_ customisation guide, these are given as the
> > best choice for heavy riders in terms of max stopping power and subtlety
> > of control. Greenspeed, unlike HPV, doesn't offer either the Martas or
> > the Avids.
>
> > Now I've been reading up on the competition, and have become confused.
> > The Avid mechanical brakes are what come as standard. I've done some
> > googling on these and have found the most incredibly consistent series
> > of rave reviews. The consensus out there seems to be - people who fork
> > out extra for hydraulic discs are plain stupid or misguided, the Avids
> > are so good as to be unbeatable on function at a much lower price and
> > much easier maintenance.
>
> > I also learn that hydraulic brakes have brake fluid which can leak, and
> > that they are a lot fiddlier to maintain, and a lot more delicate and
> > likely to fail. Is this true?
>
> > And does anyone know the difference between the Martas and the Bigs?
> > What justifies the extra price on the Martas?
>
> > I'm not quibbling on price. I will pay _whatever_is_necessary_ to get
> > the product that is best for _me_. I will be using this trike to get
> > down the very steep hills on my commute to work. I have never been able
> > to bike these descents and have trouble even walking them, such is the
> > angle. There is about a km of dizzying descent, crossed with traffic
> > intersections. I _must_ be confident that I can stop.
>
> > But simplicity of maintenance is as important as powerful stopping. The
> > other vocation of the trike will be to come touring with me in places
> > where support may not be easily found, and to be on and off planes and
> > trains. If hydraulic disks are too delicate, and by failing immobilize
> > the entire vehicle, then they may not justify their extra cost.
>
> > Thanks for your experiences. Cheers,
>
> I can lock up both from wheels on dry pavement with the Avid mechanical
> disc brakes on my trike. The feel is mushy compared to a good hydraulic
> system, however.
>
> --
> Tom Sherman - Holstein-Friesland Bovinia
> A Real Cyclist [TM] keeps at least one bicycle in the bedroom.
>
Thing is though that locking the wheels is one thing, stopping fast
and safely is another, my cheap hybrid can lock it's wheels, but i
would regard is brakes as poor, in that it wouldn't stop in hurry at
speed, while my moutain bikes will, which considering the rubber on
the road i'd probably struggle to lock wheels up.
like the other day had to do a emergency stop, squeeling of tires on
hot road but not locking.
roger
|
| | |
Date: 04 Sep 2007 14:09:41
From: Marz
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Sep 4, 3:01 am, Tony Raven <j...@raven-family.invalid > wrote:
> Paul Boyd <usenet.is.worse@plusnet> wrote innews:13dq0724878dhac@corp.supernews.com:
>
>
>
> > Less likely on a
> > tandem, but on an MTB pointing down a 60 degree loose slope you need
> > very precise braking control :-)
>
> <pedant>
>
> You can't have a 60 degree loose slope - its beyond the maximum angle of
> repose for loose material.
>
> </pedant>
>
> --
> Tony
>
> " I would never die for my beliefs because I might be wrong."
> Bertrand Russell
You can very easily have a 60 degree slope, rock face, rooty sections,
washed out river banks, but it's not something you're ever going to
attempt to brake on. When things get that steep all you're hoping to
do is roll it out without crashing.
|
| | | |
Date: 04 Sep 2007 14:26:07
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Marz <marzjennings@gmail.com > wrote in
news:1188914981.949757.199820@50g2000hsm.googlegroups.com:
> On Sep 4, 3:01 am, Tony Raven <j...@raven-family.invalid> wrote:
>> Paul Boyd <usenet.is.worse@plusnet> wrote
>> innews:13dq0724878dhac@corp.supernews.com:
>>
>>
>>
>> > Less likely on a
>> > tandem, but on an MTB pointing down a 60 degree loose slope you
>> > need very precise braking control :-)
>>
>> <pedant>
>>
>> You can't have a 60 degree loose slope - its beyond the maximum angle
>> of repose for loose material.
>>
>> </pedant>
>>
>> --
>> Tony
>>
>> " I would never die for my beliefs because I might be wrong."
>> Bertrand Russell
>
> You can very easily have a 60 degree slope, rock face, rooty sections,
> washed out river banks, but it's not something you're ever going to
> attempt to brake on. When things get that steep all you're hoping to
> do is roll it out without crashing.
>
>
But it can't be a loose slope - the loose material will just roll off it
if the slope is steeper than the maximum angle of repose which is
typically IIRC around 30-40 degrees.
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
|
| | |
Date: 04 Sep 2007 05:36:29
From: CoyoteBoy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 4 Sep, 13:16, N...@wodger.demon.co.uk (Roger Merriman) wrote:
> that as maybe certinaly at slower speeds, but ramp the speed up to and
> disks do seem to stop one faster and cleaner then rim brakes, the rim
> did stop the bike and safely, but at higher speeds they don't at least
> in my experiance attaully stop as fast.
I suspect this is down to heat buildup - a rim brake has a much higher
contact speed than a disk brake so the pads will suffer from the
effects of heat much faster. Oh and dont forget the rim pads have to
be fairly soft rubbery stuff so as not to eat the soft rims, which
doesnt help with heat dissipation and pad life.
|
| | | |
Date: 04 Sep 2007 16:19:26
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
CoyoteBoy <james.buckle@gmail.com > wrote:
> On 4 Sep, 13:16, N...@wodger.demon.co.uk (Roger Merriman) wrote:
>
> > that as maybe certinaly at slower speeds, but ramp the speed up to and
> > disks do seem to stop one faster and cleaner then rim brakes, the rim
> > did stop the bike and safely, but at higher speeds they don't at least
> > in my experiance attaully stop as fast.
>
> I suspect this is down to heat buildup - a rim brake has a much higher
> contact speed than a disk brake so the pads will suffer from the
> effects of heat much faster. Oh and dont forget the rim pads have to
> be fairly soft rubbery stuff so as not to eat the soft rims, which
> doesnt help with heat dissipation and pad life.
that would make sence yes, if you ever get the chance to ride on slag it
quite apart from making the sort of mud that all but the most clean
running mud tires clog up in, also eats pads,
roger
--
www.rogermerriman.com
|
| | | |
Date: 04 Sep 2007 08:24:19
From: Ben C
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 2007-09-04, CoyoteBoy <james.buckle@gmail.com > wrote:
> On 4 Sep, 13:16, N...@wodger.demon.co.uk (Roger Merriman) wrote:
>
>> that as maybe certinaly at slower speeds, but ramp the speed up to and
>> disks do seem to stop one faster and cleaner then rim brakes, the rim
>> did stop the bike and safely, but at higher speeds they don't at least
>> in my experiance attaully stop as fast.
>
> I suspect this is down to heat buildup - a rim brake has a much higher
> contact speed than a disk brake so the pads will suffer from the
> effects of heat much faster.
Yes but the force is lower.
For a given deceleration of a bike weighing a given amount, power
dissipation is the same, whether you're using rims or disks. Sure the
disk is moving slower past the pad but the pad is gripping it tighter.
The amount of heat transferred from the moving bike to the brakes
is the same in both cases.
Heat buildup is rate of kinetic energy dissipation minus what the brakes
can get rid of by cooling. So do disks or rims cool faster? The answer's
not obvious.
> Oh and dont forget the rim pads have to
> be fairly soft rubbery stuff so as not to eat the soft rims, which
> doesnt help with heat dissipation and pad life.
Yes, the pads on disks can possibly work over a wider range of
temperatures from cool (when you first start braking) to very hot. The
disk itself can also be allowed to get hotter since it won't blow the
tyre off the way the rim will.
|
| | |
Date: 29 Aug 2007 19:07:44
From: Tom \Johnny Sunset\ Sherman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
roger merriman wrote:
> On 29 Aug, 05:03, "Tom \"Johnny Sunset\" Sherman"
> <sunsetss0...@iinvalid.com> wrote:
>>
>> I can lock up both from wheels on dry pavement with the Avid mechanical
>> disc brakes on my trike. The feel is mushy compared to a good hydraulic
>> system, however.
>>
> Thing is though that locking the wheels is one thing, stopping fast
> and safely is another, my cheap hybrid can lock it's wheels, but i
> would regard is brakes as poor, in that it wouldn't stop in hurry at
> speed, while my moutain bikes will, which considering the rubber on
> the road i'd probably struggle to lock wheels up.
>
> like the other day had to do a emergency stop, squeeling of tires on
> hot road but not locking.
Can you lock the front wheel on your hybrid? An upright bicycle will
"pitch over" before the front wheel will lock on dry pavement.
Conversely, due to weight transfer, the rear wheel can be locked with
quite weak brakes (or almost no brake at the point where the wheel is
about to be unloaded).
On a tadpole trike with a low seat, braking is limited by tire traction
only. The available braking force is generally about 40% more than could
be produced on an upright.
--
Tom Sherman - Holstein-Friesland Bovinia
A Real Cyclist [TM] keeps at least one bicycle in the bedroom.
--
Posted via a free Usenet account from http://www.teranews.com
|
| | | |
Date: 30 Aug 2007 10:54:00
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Tom "Johnny Sunset" Sherman <sunsetss0003@iinvalid.com > wrote:
> roger merriman wrote:
> > On 29 Aug, 05:03, "Tom \"Johnny Sunset\" Sherman"
> > <sunsetss0...@iinvalid.com> wrote:
> >>
> >> I can lock up both from wheels on dry pavement with the Avid mechanical
> >> disc brakes on my trike. The feel is mushy compared to a good hydraulic
> >> system, however.
> >>
> > Thing is though that locking the wheels is one thing, stopping fast
> > and safely is another, my cheap hybrid can lock it's wheels, but i
> > would regard is brakes as poor, in that it wouldn't stop in hurry at
> > speed, while my moutain bikes will, which considering the rubber on
> > the road i'd probably struggle to lock wheels up.
> >
> > like the other day had to do a emergency stop, squeeling of tires on
> > hot road but not locking.
>
> Can you lock the front wheel on your hybrid? An upright bicycle will
> "pitch over" before the front wheel will lock on dry pavement.
> Conversely, due to weight transfer, the rear wheel can be locked with
> quite weak brakes (or almost no brake at the point where the wheel is
> about to be unloaded).
>
on the hybrid the the biggest danger in locking a wheel is looking
control than pitching over, it's weight means you'd really have to try,
possibly pitching your weight forward
but most uprights you really would have to try before pitching your self
over.
i'm used to mounatin bikes so i move my weight under braking so for
instance while it was close to i didn't lock the rear when i had to do a
emergency stop from about 20.
> On a tadpole trike with a low seat, braking is limited by tire traction
> only. The available braking force is generally about 40% more than could
> be produced on an upright.
thats the same of any bike, certinaly if you move your weight around.
but again locking ones brakes while sounds impressive doesn't stop you
as fast or as incontrol as braking to just within the limits of the
tires.
roger
--
www.rogermerriman.com
|
| | | | |
Date: 05 Sep 2007 16:02:50
From: Marz
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Sep 4, 2:26 pm, Tony Raven <j...@raven-family.invalid > wrote:
> Marz <marzjenni...@gmail.com> wrote innews:1188914981.949757.199820@50g2000hsm.googlegroups.com:
>
>
>
>
>
> > On Sep 4, 3:01 am, Tony Raven <j...@raven-family.invalid> wrote:
> >> Paul Boyd <usenet.is.worse@plusnet> wrote
> >> innews:13dq0724878dhac@corp.supernews.com:
>
> >> > Less likely on a
> >> > tandem, but on an MTB pointing down a 60 degree loose slope you
> >> > need very precise braking control :-)
>
> >> <pedant>
>
> >> You can't have a 60 degree loose slope - its beyond the maximum angle
> >> of repose for loose material.
>
> >> </pedant>
>
> >> --
> >> Tony
>
> >> " I would never die for my beliefs because I might be wrong."
> >> Bertrand Russell
>
> > You can very easily have a 60 degree slope, rock face, rooty sections,
> > washed out river banks, but it's not something you're ever going to
> > attempt to brake on. When things get that steep all you're hoping to
> > do is roll it out without crashing.
>
> But it can't be a loose slope - the loose material will just roll off it
> if the slope is steeper than the maximum angle of repose which is
> typically IIRC around 30-40 degrees.
>
> --
> Tony
>
> " I would never die for my beliefs because I might be wrong."
> Bertrand Russell- Hide quoted text -
>
> - Show quoted text -
Ahh, 'loose' slope. I should read every word and yes there is a limit
to the slope of loose material.
|
| | | | |
Date: 30 Aug 2007 06:46:33
From: Tom \Johnny Sunset\ Sherman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Roger Merriman wrote:
> Tom "Johnny Sunset" Sherman <sunsetss0003@iinvalid.com> wrote:
>
>> roger merriman wrote:
>>> On 29 Aug, 05:03, "Tom \"Johnny Sunset\" Sherman"
>>> <sunsetss0...@iinvalid.com> wrote:
>>>> I can lock up both from wheels on dry pavement with the Avid mechanical
>>>> disc brakes on my trike. The feel is mushy compared to a good hydraulic
>>>> system, however.
>>>>
>>> Thing is though that locking the wheels is one thing, stopping fast
>>> and safely is another, my cheap hybrid can lock it's wheels, but i
>>> would regard is brakes as poor, in that it wouldn't stop in hurry at
>>> speed, while my moutain bikes will, which considering the rubber on
>>> the road i'd probably struggle to lock wheels up.
>>>
>>> like the other day had to do a emergency stop, squeeling of tires on
>>> hot road but not locking.
>> Can you lock the front wheel on your hybrid? An upright bicycle will
>> "pitch over" before the front wheel will lock on dry pavement.
>> Conversely, due to weight transfer, the rear wheel can be locked with
>> quite weak brakes (or almost no brake at the point where the wheel is
>> about to be unloaded).
>>
> on the hybrid the the biggest danger in locking a wheel is looking
> control than pitching over, it's weight means you'd really have to try,
> possibly pitching your weight forward
>
> but most uprights you really would have to try before pitching your self
> over.
>
> i'm used to mounatin bikes so i move my weight under braking so for
> instance while it was close to i didn't lock the rear when i had to do a
> emergency stop from about 20.
On my Trek 6000 (hard-tail) I can easily do a "stoppie", getting the
rear wheel a foot or so in the air as I come to a stop. Since I brace
myself properly, there is not real danger of going over the bars.
However, there is no front wheel skidding, even with the knobby off-road
tires.
>> On a tadpole trike with a low seat, braking is limited by tire traction
>> only. The available braking force is generally about 40% more than could
>> be produced on an upright.
>
> thats the same of any bike, certinaly if you move your weight around.
I would be shocked if anyone on an upright could come close to matching
the braking of a tadpole with a low seat. Do the calculations, and you
will see that the upright pitches over between 0.6 and 0.7g, while the
tadpole is limited only by available friction.
> but again locking ones brakes while sounds impressive doesn't stop you
> as fast or as incontrol as braking to just within the limits of the
> tires.
Agreed. However, my point is while proper hydraulic disc brakes can be
considered the best braking system for a tadpole, the Avid mechanical
discs are more than adequate.
--
Tom Sherman - Holstein-Friesland Bovinia
A Real Cyclist [TM] keeps at least one bicycle in the bedroom.
--
Posted via a free Usenet account from http://www.teranews.com
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Date: 30 Aug 2007 13:02:45
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Tom "Johnny Sunset" Sherman wrote:
> Agreed. However, my point is while proper hydraulic disc brakes can be
> considered the best braking system for a tadpole, the Avid mechanical
> discs are more than adequate.
But that reduces the argument to stopping power only. Hydraulics give
you more control over the power because your fingers don't need to do a
Big heave to get the power. That's why I prefer hydraulics, not
anything to do with absolute available power: they're just plain nicer
to use.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 30 Aug 2007 16:51:09
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>But that reduces the argument to stopping power only. Hydraulics give
>you more control over the power because your fingers don't need to do a
>Big heave to get the power.
I never understood the "big heave" argument. At the end of a day on the
bike, it's not my fingers that are tired!
--
David Damerell <damerell@chiark.greenend.org.uk > Distortion Field!
Today is Second Monday, August.
|
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Date: 05 Sep 2007 10:37:36
From:
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 5 Sep,
Peter Clinch <p.j.clinch@dundee.ac.uk > wrote:
> Tony Raven wrote:
>
> > I stand corrected then but going back to the OP, do you think the
> > situation of "on an MTB pointing down a 60 degree loose slope you need
> > very precise braking control" is realistic. I recognise there are 60
> > degree slopes but there is unlikely to be any loose material on them and
> > I somehow doubt the rear wheel would stay down if you tried to brake.
>
> I can see such a slope existing if one takes "loose" as "stuck on... but
> not at all well, and not enough to stay put when a bike hits it", but I'd
> agree that anyone going down 60 degree slopes on a bike is pretty much
> wasting their time with the brakes! 60 degrees is actually typical of
> lower grade rock climbing, and IME people very often over-estimate true
> steepness of steep slopes (where "steep" starts at about 20 degrees).
A slope of 45 degrees would require a coefficient of friction of one just to
stay on it. Coefficients higher than one are unusual, perhaps limiting at
about 1.1 with sticky tyres. It would be impossible to stay put, nevermind
brake to a halt, on a 60 degree slope, unless there was an interlocking rack
and pinion arrangement.
--
BD
Change lycos to yahoo to reply
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Date: 31 Aug 2007 08:40:23
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> I never understood the "big heave" argument. At the end of a day on the
> bike, it's not my fingers that are tired!
Nor are mine, but during use hydraulics are more pleasant because you
don't need to heave right there and then, whether or not fingers are
tired later on.
I never understood the arguments for hydraulics before I used them.
Having used them somewhat by accident (a demo 'bent had some HS11s on),
I bought some, and have never regretted it. They are simply much better
in use than cable brakes IME.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 31 Aug 2007 14:18:00
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>I never understood the "big heave" argument. At the end of a day on the
>>bike, it's not my fingers that are tired!
>Nor are mine, but during use hydraulics are more pleasant because you
>don't need to heave right there and then,
This just doesn't make sense. The difference between moderate and light
hand force is completely trivial.
>I never understood the arguments for hydraulics before I used them.
>Having used them somewhat by accident (a demo 'bent had some HS11s on),
>I bought some, and have never regretted it. They are simply much better
>in use than cable brakes IME.
I've used them during a demo too, and this is one of those strange senses
of "better" that doesn't actually mean "better". Cable brakes stop the
bike and with a sensible setup (hem-hem ie not some horrible grabby V
setup) they are nicely predictable.
I suspect this is the usual problem where a bad setup (eg, grabby Vs) is
compared with a good one and the difference is ascribed to the underlying
technology not the setup. That's particularly likely here because it's
obviously jolly hard to get a hydraulic setup that has that particular
problem.
--
David Damerell <damerell@chiark.greenend.org.uk > Distortion Field!
Today is Second Tuesday, August.
|
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Date: 01 Sep 2007 08:39:01
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell said the following on 31/08/2007 14:18:
> I've used them during a demo too, and this is one of those strange senses
> of "better" that doesn't actually mean "better". Cable brakes stop the
> bike and with a sensible setup (hem-hem ie not some horrible grabby V
> setup) they are nicely predictable.
Have you actually used hydraulic brakes extensively in a variety of
situations, or just on this demo? Peter summed it up quite nicely:-
"better means nicer, and most of us think nicer is better"
--
Paul Boyd
http://www.paul-boyd.co.uk/
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Date: 31 Aug 2007 15:22:09
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> This just doesn't make sense. The difference between moderate and light
> hand force is completely trivial.
So that's why all the best game controllers use heavy joysticks?
> I've used them during a demo too, and this is one of those strange senses
> of "better" that doesn't actually mean "better".
No, it's where better means nicer, and most of us think nicer is better.
> Cable brakes stop the
> bike and with a sensible setup (hem-hem ie not some horrible grabby V
> setup) they are nicely predictable.
They are, but they're still not as nice to use as hydraulics. Just as
is the case with power and manual steering on a small car. There's no
particular problem driving a small car without power steering, but
pretty much everyone prefers power steering.
> I suspect this is the usual problem where a bad setup (eg, grabby Vs) is
> compared with a good one and the difference is ascribed to the underlying
> technology not the setup.
No, it's moving from one demo bike with well set up cable brakes
(typically Avid disks) before the cables have degraded to a bike with
hydraulics and just finding they're nicer because they can be used
better with just fingertip pressure.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 31 Aug 2007 19:46:38
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>This just doesn't make sense. The difference between moderate and light
>>hand force is completely trivial.
>So that's why all the best game controllers use heavy joysticks?
Conversely, most PC joysticks are big chunky things - and, guess what,
it's easier to fine tune adjustment when "hard over" isn't a centimetre
away from "dead centre" and you can't do "hard over" just by flicking it.
>hydraulics and just finding they're nicer because they can be used
>better with just fingertip pressure.
So what's better about fingertips versus a gentle pull with the fingers?
You might as well prefer them because they come in your favourite colour.
Preferring a brake that doesn't make you squeeze like you're using one of
those hand exercisers makes perfect sense, but once you get down to a
moderate pressure that doesn't give you sore hands at the end of the day,
well, less pressure than that is just an arbitary personal preference.
--
David Damerell <damerell@chiark.greenend.org.uk > Distortion Field!
Today is Second Tuesday, August.
|
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Date: 04 Sep 2007 08:14:36
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> Conversely, most PC joysticks are big chunky things - and, guess what,
> it's easier to fine tune adjustment when "hard over" isn't a centimetre
> away from "dead centre" and you can't do "hard over" just by flicking it.
You seem to have mistaken travel for force required.
> So what's better about fingertips versus a gentle pull with the fingers?
"Fingertips" *is* a nice gentle pull with your fingers. Try that on a
setup like Clive's where the cables haven't been touched for a decade on
mechanicals and all you'll get with a gentle pull with the fingers on a
worryingly accelerating tandem is panic-stricken...
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 04 Sep 2007 15:10:33
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>Conversely, most PC joysticks are big chunky things - and, guess what,
>>it's easier to fine tune adjustment when "hard over" isn't a centimetre
>>away from "dead centre" and you can't do "hard over" just by flicking it.
>You seem to have mistaken travel for force required.
No, both are large compared to a games console controller.
>>So what's better about fingertips versus a gentle pull with the fingers?
>"Fingertips" *is* a nice gentle pull with your fingers. Try that on a
>setup like Clive's where the cables haven't been touched for a decade on
>mechanicals and all you'll get with a gentle pull with the fingers on a
> worryingly accelerating tandem is panic-stricken...
Yes, an unmaintained brake can be dangerous. Not a new fact.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Second Saturday, August - a weekend.
|
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Date: 04 Sep 2007 15:33:05
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> Yes, an unmaintained brake can be dangerous. Not a new fact.
You've gloriously and spectacularly missed the fact that Clive's
hydraulic brakes haven't been maintained for the precise reason that
they haven't /needed/ maintaining in order not to degrade unacceptably,
as manifestly doesn't happen with "just as good" mechanical brakes.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 05 Sep 2007 17:15:57
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>Yes, an unmaintained brake can be dangerous. Not a new fact.
>You've gloriously and spectacularly missed the fact that Clive's
>hydraulic brakes haven't been maintained for the precise reason that
>they haven't /needed/ maintaining in order not to degrade unacceptably,
Well, no. There's a dodge going on here where the real advantage of not
needing as much maintenance is twisted into better performance (because
the performance is better when unmaintained). That's double accounting; if
you're going to argue based on the unmaintained performance, you can't
argue that they need less maintenance.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
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Date: 06 Sep 2007 08:32:29
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> Well, no. There's a dodge going on here where the real advantage of not
> needing as much maintenance is twisted into better performance (because
> the performance is better when unmaintained). That's double accounting; if
> you're going to argue based on the unmaintained performance, you can't
> argue that they need less maintenance.
Two things:
1) maintenance is an improved feature
2) performance, via better control through more sensitivity, is an
improved feature.
It's in the books as two things because it's two things. The
maintenance angle is better, and the performance is better, quite
independently. But if you don't do all the maintenance on a mech cable
then the hydraulic performs much, much better, rather than merely a
(tangibly) bit better.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 06 Sep 2007 16:32:19
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>Well, no. There's a dodge going on here where the real advantage of not
>>needing as much maintenance is twisted into better performance (because
>>the performance is better when unmaintained). That's double accounting; if
>>you're going to argue based on the unmaintained performance, you can't
>>argue that they need less maintenance.
>Two things:
>1) maintenance is an improved feature
>2) performance, via better control through more sensitivity, is an
>improved feature.
But that's a dodge. What you were talking about was performance via not
degrading as badly when unmaintained, and that's double accounting with
"less maintenance".
Performance via better control through more sensitivity is something
that's basically been made up here. It's the usual confusion - "this
_feels_ better so it must _be_ better" (combined with "this feels better
_to me_ so it must be better _for everyone_").
As I've just written in another article - too much sensitivity won't work,
too much force won't work. Somewhere between there's a sweet spot or
region; when you say you know that's a spot and it happens to be where
your brake setup is - for every user, no less - you're just speculating.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 07 Sep 2007 09:15:47
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> But that's a dodge. What you were talking about was performance via not
> degrading as badly when unmaintained, and that's double accounting with
> "less maintenance".
Oh deary me, I have talked about *both* performance being better through
better feel when maintained and being better in all respects when not
maintained and left for some time.
That's two things. Both are better with hydraulics.
> Performance via better control through more sensitivity is something
> that's basically been made up here.
No, it's based on direct experience. How much experience do you
actually have of hydraulic brakes? How much experience do world cup
MTBers have of hydraulic brakes? And which actuation method do they prefer?
> It's the usual confusion - "this
> _feels_ better so it must _be_ better" (combined with "this feels better
> _to me_ so it must be better _for everyone_").
As opposed to "this is what I use and I think it's fine so obviously
anyone else finding anuthing better is deluded"...
> As I've just written in another article - too much sensitivity won't work,
It isn't "too much" that hydraulics give you, it's more than cables, but
less than too much. A better amount, in other words.
> too much force won't work. Somewhere between there's a sweet spot or
> region; when you say you know that's a spot and it happens to be where
> your brake setup is - for every user, no less - you're just speculating.
For every user, no, but if one is playing the advice/probability game
then you go with a best liklihood, and it's most likely that A Given
User will find hydraulics better in use than cables to start with, and
quite a bit better than that with time as the cables fail to degrade
IMHO. How much experience of hydraulic brakes do you actually have?
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 07 Sep 2007 18:52:41
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>But that's a dodge. What you were talking about was performance via not
>>degrading as badly when unmaintained, and that's double accounting with
>>"less maintenance".
>Oh deary me, I have talked about *both* performance being better through
>better feel when maintained and being better in all respects when not
>maintained and left for some time.
>That's two things.
The second of which is then double accounting with "less maintenance".
>>It's the usual confusion - "this
>>_feels_ better so it must _be_ better" (combined with "this feels better
>>_to me_ so it must be better _for everyone_").
>As opposed to "this is what I use and I think it's fine so obviously
>anyone else finding anuthing better is deluded"...
That's a perfectly reasonable thing to say when someone pretends their
personal prefence is universally applicable.
>>As I've just written in another article - too much sensitivity won't work,
>It isn't "too much" that hydraulics give you, it's more than cables, but
>less than too much. A better amount, in other words.
There must be a sweet spot not a region of equal utility because...
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Leicesterday, August.
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Date: 30 Aug 2007 21:15:34
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Peter Clinch <p.j.clinch@dundee.ac.uk>:
> >But that reduces the argument to stopping power only. Hydraulics give
> >you more control over the power because your fingers don't need to do a
> >Big heave to get the power.
>
> I never understood the "big heave" argument. At the end of a day on the
> bike, it's not my fingers that are tired!
need to ride down a proper hill then! ;-) my old mountain bike, used off
or on road as i used to nr my folks place has terrible brakes, back to
around london/surrey it's fine if not quite good.
it's only down long steep hills or other extremes that you'll see the
differnace. on older weeker calipers (1) your forearms will acke by the
time you reach the bottem, with super wizz bang disk brakes you don't
have to hang on to the brakes, but just squeeze them as and when needed.
on road it makes less differnace so the reason to have them is less.
(1) yes i know calipers differ greatly in power.
roger
--
www.rogermerriman.com
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Date: 31 Aug 2007 00:01:44
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Quoting Peter Clinch <p.j.clinch@dundee.ac.uk>:
>>>But that reduces the argument to stopping power only. Hydraulics give
>>>you more control over the power because your fingers don't need to do a
>>>Big heave to get the power.
>>I never understood the "big heave" argument. At the end of a day on the
>>bike, it's not my fingers that are tired!
>need to ride down a proper hill then!
I've ridden down every hill in the country [1] with two people's lard to
brake and only one person's air resistance. It still wasn't my fingers
that were tired at the end of each day.
[1] on a long line between LE and JOG.
--
David Damerell <damerell@chiark.greenend.org.uk > flcl?
Today is Second Tuesday, August.
|
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Date: 31 Aug 2007 00:17:16
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Quoting Peter Clinch <p.j.clinch@dundee.ac.uk>:
> >>>But that reduces the argument to stopping power only. Hydraulics give
> >>>you more control over the power because your fingers don't need to do a
> >>>Big heave to get the power.
> >>I never understood the "big heave" argument. At the end of a day on the
> >>bike, it's not my fingers that are tired!
> >need to ride down a proper hill then!
>
> I've ridden down every hill in the country [1] with two people's lard to
> brake and only one person's air resistance. It still wasn't my fingers
> that were tired at the end of each day.
>
on the road brakes really are less of a issue, even travelling fast,
you'd have to be going very fast before it did.
the road that drops from the havard down to though to crickhowel is
fairly steep one and long and yet even that you only get slight i'm
useing the brakes a bit feel not a attaully twinge. unlike off road
where decending with old bikes and old brakes by the time you'd reached
the bottom you can feel it in your forearms, if you mostly ride on road
then you not need to brake for as long nor as hard.
> [1] on a long line between LE and JOG.
not a acronym i know sorry.
roger
--
www.rogermerriman.com
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Date: 31 Aug 2007 14:13:16
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>I've ridden down every hill in the country [1] with two people's lard to
>>brake and only one person's air resistance. It still wasn't my fingers
>>that were tired at the end of each day.
>on the road brakes really are less of a issue,
This is typical of this sort of discussion. What starts as an unqualified
"X is best" turns out to be "X is best off-road on a Sunday with your
underpants on your head", or whatever else doesn't fit the experience of
whoever is replying.
Why not _mention_ that from the start?
>useing the brakes a bit feel not a attaully twinge. unlike off road
>where decending with old bikes and old brakes by the time you'd reached
>the bottom you can feel it in your forearms, if you mostly ride on road
>then you not need to brake for as long nor as hard.
That depends. A tandem often needs a lot more braking.
--
David Damerell <damerell@chiark.greenend.org.uk > Distortion Field!
Today is Second Tuesday, August.
|
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Date: 31 Aug 2007 21:02:27
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>I've ridden down every hill in the country [1] with two people's lard to
> >>brake and only one person's air resistance. It still wasn't my fingers
> >>that were tired at the end of each day.
> >on the road brakes really are less of a issue,
>
> This is typical of this sort of discussion. What starts as an unqualified
> "X is best" turns out to be "X is best off-road on a Sunday with your
> underpants on your head", or whatever else doesn't fit the experience of
> whoever is replying.
>
> Why not _mention_ that from the start?
not sure it was terribly needed, after all mountain bikes have strived
for bigger better etc brakes while there hasn't been such a pressing
need on road. that off road pushes brakes more is pritty much a given.
>
> >useing the brakes a bit feel not a attaully twinge. unlike off road
> >where decending with old bikes and old brakes by the time you'd reached
> >the bottom you can feel it in your forearms, if you mostly ride on road
> >then you not need to brake for as long nor as hard.
>
> That depends. A tandem often needs a lot more braking.
yes, though probably not as much as mountain bike.
roger
--
www.rogermerriman.com
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Date: 31 Aug 2007 22:11:30
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Roger Merriman" <NEWS@wodger.demon.co.uk > wrote in message
news:1i3q9v6.hww1nv1ylxv0rN%NEWS@wodger.demon.co.uk...
>> That depends. A tandem often needs a lot more braking.
>
> yes, though probably not as much as mountain bike.
Mmm. You may well be understimating the effects of the doubled weight,
similar frontal area and ability to put the brakes on as hard as you like
without fear of an endo...
cheers,
clive
|
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Date: 02 Sep 2007 22:36:56
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Clive George <clive@xxxx-x.fsnet.co.uk > wrote:
> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote in message
> news:1i3q9v6.hww1nv1ylxv0rN%NEWS@wodger.demon.co.uk...
>
> >> That depends. A tandem often needs a lot more braking.
> >
> > yes, though probably not as much as mountain bike.
>
> Mmm. You may well be understimating the effects of the doubled weight,
> similar frontal area and ability to put the brakes on as hard as you like
> without fear of an endo...
>
> cheers,
> clive
i can't rember the last time i did a endo, by braking, probably when i
was a kid. normally the tires loose traction way before that point at
least on a mounatin bike, i grew up in a steep sided gorge thus one gets
used to shifting weight for braking etc, and hill starts in cars as well
it must be said.
i would expect a tamdem to require much more braking than a single. but
most tamdems are used onroad which is a much less demanding than
mountain bikes use (1) plus i guess the market for tamdems is smaller so
doesn't get the money poured in that the mountain bikes do.
roger
--
www.rogermerriman.com
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Date: 03 Sep 2007 01:03:42
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Roger Merriman" <NEWS@wodger.demon.co.uk > wrote in message
news:1i3ralr.ljo91213p8q4hN%NEWS@wodger.demon.co.uk...
> Clive George <clive@xxxx-x.fsnet.co.uk> wrote:
>
>> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote in message
>> news:1i3q9v6.hww1nv1ylxv0rN%NEWS@wodger.demon.co.uk...
>>
>> >> That depends. A tandem often needs a lot more braking.
>> >
>> > yes, though probably not as much as mountain bike.
>>
>> Mmm. You may well be understimating the effects of the doubled weight,
>> similar frontal area and ability to put the brakes on as hard as you like
>> without fear of an endo...
>
> i can't rember the last time i did a endo, by braking, probably when i
> was a kid. normally the tires loose traction way before that point at
> least on a mounatin bike, i grew up in a steep sided gorge thus one gets
> used to shifting weight for braking etc, and hill starts in cars as well
> it must be said.
>
> i would expect a tamdem to require much more braking than a single. but
> most tamdems are used onroad which is a much less demanding than
> mountain bikes use (1) plus i guess the market for tamdems is smaller so
> doesn't get the money poured in that the mountain bikes do.
An impressive post, wrong in quite so many ways :-)
Here's the deal:
You've learned not to endo, through a combination of weight shifting and
controlling the braking required. Tandems don't need that, especially on
road, which means you can abuse the brakes rather more than you can on an
MTB.
The enemy of brakes is heat. Brakes which cope with MTBing fine will die
when used by a tandem, even on road - there really is that much more energy
available.
Check out Santana's brake testing results, and the brakes SJSC will
recommend you use on a tandem - these people have tried it, and know just
how much abuse a tandem can provide for brakes :-)
And while you're there, check out the prices and consider your "money poured
in" comment (even though it's amusingly bogus :-) )
cheers,
clive
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Date: 03 Sep 2007 08:51:16
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Clive George <clive@xxxx-x.fsnet.co.uk > wrote:
> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote in message
> news:1i3ralr.ljo91213p8q4hN%NEWS@wodger.demon.co.uk...
> > Clive George <clive@xxxx-x.fsnet.co.uk> wrote:
> >
> >> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote in message
> >> news:1i3q9v6.hww1nv1ylxv0rN%NEWS@wodger.demon.co.uk...
> >>
> >> >> That depends. A tandem often needs a lot more braking.
> >> >
> >> > yes, though probably not as much as mountain bike.
> >>
> >> Mmm. You may well be understimating the effects of the doubled weight,
> >> similar frontal area and ability to put the brakes on as hard as you like
> >> without fear of an endo...
> >
> > i can't rember the last time i did a endo, by braking, probably when i
> > was a kid. normally the tires loose traction way before that point at
> > least on a mounatin bike, i grew up in a steep sided gorge thus one gets
> > used to shifting weight for braking etc, and hill starts in cars as well
> > it must be said.
> >
> > i would expect a tamdem to require much more braking than a single. but
> > most tamdems are used onroad which is a much less demanding than
> > mountain bikes use (1) plus i guess the market for tamdems is smaller so
> > doesn't get the money poured in that the mountain bikes do.
>
> An impressive post, wrong in quite so many ways :-)
>
> Here's the deal:
>
> You've learned not to endo, through a combination of weight shifting and
> controlling the braking required. Tandems don't need that, especially on
> road, which means you can abuse the brakes rather more than you can on an
> MTB.
> The enemy of brakes is heat. Brakes which cope with MTBing fine will die
> when used by a tandem, even on road - there really is that much more energy
> available.
>
okay fair enought.
> Check out Santana's brake testing results, and the brakes SJSC will
> recommend you use on a tandem - these people have tried it, and know just
> how much abuse a tandem can provide for brakes :-)
>
which begs the other question if tamdems have allways or for a reasonble
time had half decent brakes why did it not filter to mountain bikes?
racing bikes i can get as weight etc.
> And while you're there, check out the prices and consider your "money poured
> in" comment (even though it's amusingly bogus :-) )
>
thats was about companies than indivuals. ie lots of mountain bikes thus
bigger market etc.
> cheers,
> clive
roger
--
www.rogermerriman.com
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Date: 03 Sep 2007 17:30:34
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>which begs the other question if tamdems have allways or for a reasonble
>time had half decent brakes why did it not filter to mountain bikes?
Because mountain bikes can't actually use any more braking than any other
solo bike.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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| | | | | | | | | | | | | | | | | |
Date: 03 Sep 2007 20:24:15
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >which begs the other question if tamdems have allways or for a reasonble
> >time had half decent brakes why did it not filter to mountain bikes?
>
> Because mountain bikes can't actually use any more braking than any other
> solo bike.
really? funny the jump though various cable rim brakes to hydraulic
disks has been a steady improvement in braking.
roger
--
www.rogermerriman.com
|
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Date: 04 Sep 2007 15:09:14
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Because mountain bikes can't actually use any more braking than any other
>>solo bike.
>really? funny the jump though various cable rim brakes to hydraulic
>disks has been a steady improvement in braking.
No, there hasn't. With a well adjusted cable rim brake you can lift the
rear wheel (or skid the front on a poor surface). How can a hydraulic disc
offer more braking than that? It can't.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Second Saturday, August - a weekend.
|
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Date: 04 Sep 2007 16:19:27
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Because mountain bikes can't actually use any more braking than any other
> >>solo bike.
> >really? funny the jump though various cable rim brakes to hydraulic
> >disks has been a steady improvement in braking.
>
> No, there hasn't. With a well adjusted cable rim brake you can lift the
> rear wheel (or skid the front on a poor surface). How can a hydraulic disc
> offer more braking than that? It can't.
one at lower speeds it offers more control ie your not just janking on
the lever.
2nd at higher speeds you will have a job to lock the wheel, unless you
delbertly unweight a wheel etc.
on loose surfaces point one will help one get to but not over the point
the tires skid.
roger
--
www.rogermerriman.com
|
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Date: 05 Sep 2007 17:13:26
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>No, there hasn't. With a well adjusted cable rim brake you can lift the
>>rear wheel (or skid the front on a poor surface). How can a hydraulic disc
>>offer more braking than that? It can't.
>one at lower speeds it offers more control ie your not just janking on
>the lever.
If you're just "yanking on the lever" with a well-adjusted cable rim
brake, that's your poor technique.
>2nd at higher speeds you will have a job to lock the wheel, unless you
>delbertly unweight a wheel etc.
This one won't wash with anyone who has made emergency stops downhill on
road. We might not brake as much, but the speeds are higher.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 06 Sep 2007 10:29:07
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>No, there hasn't. With a well adjusted cable rim brake you can lift the
> >>rear wheel (or skid the front on a poor surface). How can a hydraulic disc
> >>offer more braking than that? It can't.
> >one at lower speeds it offers more control ie your not just janking on
> >the lever.
>
> If you're just "yanking on the lever" with a well-adjusted cable rim
> brake, that's your poor technique.
>
no it is easyer to make a controlled emergency stop if the lever
requires less force.
> >2nd at higher speeds you will have a job to lock the wheel, unless you
> >delbertly unweight a wheel etc.
>
> This one won't wash with anyone who has made emergency stops downhill on
> road. We might not brake as much, but the speeds are higher.
if your locking managing to lock the wheels at high speeds in the dry
etc then you either have tires with not enought grip or are not
countering with your weight. which a hill would help with.
i use my old mounatin bike on road, with road tires yes they have lot
more of footprint on the road, and i'm used to shifting weight. only the
other week i had to do a emergency stop down hill, no i didn't lock the
tires, i came close there was bit of slewing but not attaul locking.
roger
--
www.rogermerriman.com
|
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Date: 06 Sep 2007 16:28:37
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>If you're just "yanking on the lever" with a well-adjusted cable rim
>>brake, that's your poor technique.
>no it is easyer to make a controlled emergency stop if the lever
>requires less force.
This is not necessarily true. If the brake could be put completely on with
the touch of a feather, it would be impossible to make a controlled
emergency stop; if the brake required your absolute maximum hand strength
to put on, it would also be impossible. Therefore it is nonsense to say
that less (or more) force always makes it easier.
Somewhere between those two points is a spot or region where it is
easiest, but to say that that's a spot not a region and that that spot
happens to be the amount of force required by the brakes you have _and_
that that will be true for any user is pure guesswork.
>>>2nd at higher speeds you will have a job to lock the wheel, unless you
>>>delbertly unweight a wheel etc.
>>This one won't wash with anyone who has made emergency stops downhill on
>>road. We might not brake as much, but the speeds are higher.
>if your locking managing to lock the wheels at high speeds in the dry
>etc then you either have tires with not enought grip or are not
>countering with your weight. which a hill would help with.
Did I say I'd locked the wheels? No.
But - more than once - descending at speed, with heavy panniers (so with
the overall centre of gravity already lower and to the rear) - I've
had to brake so hard it's finished with the thump of the rear wheel
regaining contact with the road.
Bog ordinary cantilevers. You don't need hydraulic discs to make a
controller emergency stop at high speeds.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 07 Sep 2007 09:07:53
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> This is not necessarily true. If the brake could be put completely on with
> the touch of a feather, it would be impossible to make a controlled
> emergency stop; if the brake required your absolute maximum hand strength
> to put on, it would also be impossible. Therefore it is nonsense to say
> that less (or more) force always makes it easier.
>
> Somewhere between those two points is a spot or region where it is
> easiest, but to say that that's a spot not a region and that that spot
> happens to be the amount of force required by the brakes you have _and_
> that that will be true for any user is pure guesswork.
But rather less guesswork if they happen to have considerable experience
of multiple brake systems. How much time have you actually spent using
hydraulic brake systems?
> Bog ordinary cantilevers. You don't need hydraulic discs to make a
> controller emergency stop at high speeds.
No, but that doesn't mean to say it wouldn't be easier. Again I ask,
how much time have you actually spent using hydraulic brake systems?
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 07 Sep 2007 18:50:17
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>Somewhere between those two points is a spot or region where it is
>>easiest, but to say that that's a spot not a region and that that spot
>>happens to be the amount of force required by the brakes you have _and_
>>that that will be true for any user is pure guesswork.
>But rather less guesswork if they happen to have considerable experience
>of multiple brake systems.
And of being multiple people, if the guesswork is going to express more
than personal preference.
>How much time have you actually spent using hydraulic brake systems?
I think I'll spare myself the "I have more experience therefore my guess
is correct", thanks.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Leicesterday, August.
|
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Date: 07 Sep 2007 21:14:14
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
>> How much time have you actually spent using hydraulic brake systems?
>
> I think I'll spare myself the "I have more experience therefore my guess
> is correct", thanks.
That's a nice little sidestep to admitting "practically none at
all, so I'm working almost entirely from theory".
It isn't do I have more, it's do you have much to speak of
whatsoever? If you don't, and I suspect you don't, it's a bit like
Shaun Murray "proving" Alex Moulton hasn't got a clue about
designing road-going suspension based on his "technical mind" and a
trip around the block on an AM, or Nick Maclaren "proving" that
Bromptons are inherently unsafe for tall riders armed with nothing
but a measuring tape.
If I'm wrong about that then an apology is deserved and will be
supplied, but am I?
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 10 Sep 2007 14:48:14
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>>How much time have you actually spent using hydraulic brake systems?
>>I think I'll spare myself the "I have more experience therefore my guess
>>is correct", thanks.
>That's a nice little sidestep to admitting "practically none at
>all, so I'm working almost entirely from theory".
Well, imagine I do admit that. Let's imagine, not only have I never ridden
a bike with hydraulic discs, I've actually never seen one. When this
thread started, I didn't even know they existed, and I had to go and do a
little reading to find out what they were. In fact, I've only ever used
rod brakes and a little parachute for downhill work.
Let's imagine all that. Would that make your guesswork any less guesswork?
No.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
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5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
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Date: 10 Sep 2007 15:17:53
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> Quoting Peter Clinch <p.j.clinch@dundee.ac.uk>:
>> David Damerell wrote:
>>>> How much time have you actually spent using hydraulic brake systems?
>>> I think I'll spare myself the "I have more experience therefore my guess
>>> is correct", thanks.
>> That's a nice little sidestep to admitting "practically none at
>> all, so I'm working almost entirely from theory".
>
> Well, imagine I do admit that. Let's imagine, not only have I never ridden
> a bike with hydraulic discs, I've actually never seen one. When this
> thread started, I didn't even know they existed, and I had to go and do a
> little reading to find out what they were. In fact, I've only ever used
> rod brakes and a little parachute for downhill work.
>
> Let's imagine all that. Would that make your guesswork any less guesswork?
> No.
A while ago you castigated Roger for just not coming out and saying he
was talking about steep and radical off-road. Why don't you just come
out and quantify the experience you have with hydraulic brakes so as to
inform other people reading the thread exactly what degree of experience
and what degree of conjecture and theory your comments are based on?
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 10 Sep 2007 17:38:51
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>>>David Damerell wrote:
>>>>I think I'll spare myself the "I have more experience therefore my guess
>>>>is correct", thanks.
>was talking about steep and radical off-road. Why don't you just come
>out and quantify the experience you have with hydraulic brakes so as to
>inform other people reading the thread exactly what degree of experience
>and what degree of conjecture and theory your comments are based on?
I think I've already answered that one, just above. No matter how much or
how little experience I have, your guesswork remains guesswork. I'm sure
you'd love to produce a spurious justification of it on those grounds; too
bad (except inasmuch as you will now say something like "obviously you
don't really have any experience" and use that to justify your pure
guesswork, which will still be nonsense.)
--
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e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 10 Sep 2007 21:00:03
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> I think I've already answered that one, just above.
What you've done is come up with a precious excuse for not actually
letting on whether you know what you're talking about from
experience or just from theory (guesswork, in other words, even if
educated guesswork).
> No matter how much or
> how little experience I have, your guesswork remains guesswork.
I specifically pointed out I didn't know what experience you
actually had, and asked for clarification. Which you rather
pathetically persist in avoiding giving.
If someone is reading the thread wanting advice it is to their
advantage if the basis of any advice they get is known.
So why not just stop with the precious justifications of not
actually saying whether your opinions are based on experience or
just theory, and let people know? Do you actually want to provide
useful information, or just pour scorn on people?
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 06 Sep 2007 18:01:29
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>If you're just "yanking on the lever" with a well-adjusted cable rim
> >>brake, that's your poor technique.
> >no it is easyer to make a controlled emergency stop if the lever
> >requires less force.
>
> This is not necessarily true. If the brake could be put completely on with
> the touch of a feather, it would be impossible to make a controlled
> emergency stop; if the brake required your absolute maximum hand strength
> to put on, it would also be impossible. Therefore it is nonsense to say
> that less (or more) force always makes it easier.
>
> Somewhere between those two points is a spot or region where it is
> easiest, but to say that that's a spot not a region and that that spot
> happens to be the amount of force required by the brakes you have _and_
> that that will be true for any user is pure guesswork.
>
yes still needs to be some resistance, or it would be too easy to be a
system that was on/off
> >>>2nd at higher speeds you will have a job to lock the wheel, unless you
> >>>delbertly unweight a wheel etc.
> >>This one won't wash with anyone who has made emergency stops downhill on
> >>road. We might not brake as much, but the speeds are higher.
> >if your locking managing to lock the wheels at high speeds in the dry
> >etc then you either have tires with not enought grip or are not
> >countering with your weight. which a hill would help with.
>
> Did I say I'd locked the wheels? No.
look back at your post not the snippage here, you pritty much did if not
in actualality.
>
> But - more than once - descending at speed, with heavy panniers (so with
> the overall centre of gravity already lower and to the rear) - I've
> had to brake so hard it's finished with the thump of the rear wheel
> regaining contact with the road.
yes, but it's very unlikely the paniers are close to your weight, you
can make a much more impact moving your body, assuming the bike allows
it, that is.
>
> Bog ordinary cantilevers. You don't need hydraulic discs to make a
> controller emergency stop at high speeds.
no you don't but all things being equal they should make a better job of
it. it's a over used line but power is nothing with out control.
look do you really think that it's a big con and that brakes haven't
improved over the years? motor vehicals have been useing disks and
hydraulic at that for years, that some companies put some that where
simply not up for the job says more about those companies than what
hydraulic disks can and can't do.
roger
--
www.rogermerriman.com
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Date: 06 Sep 2007 20:27:45
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Somewhere between those two points is a spot or region where it is
>>easiest, but to say that that's a spot not a region and that that spot
>>happens to be the amount of force required by the brakes you have _and_
>>that that will be true for any user is pure guesswork.
>yes still needs to be some resistance, or it would be too easy to be a
>system that was on/off
Reducing your guesswork to what it is.
>>>if your locking managing to lock the wheels at high speeds in the dry
>>>etc then you either have tires with not enought grip or are not
>>>countering with your weight. which a hill would help with.
>>id I say I'd locked the wheels? No.
>look back at your post not the snippage here, you pritty much did if not
>in actualality.
Let's see a quote from you that shows it, then. Hint; you can't.
>>But - more than once - descending at speed, with heavy panniers (so with
>>the overall centre of gravity already lower and to the rear) - I've
>>had to brake so hard it's finished with the thump of the rear wheel
>>regaining contact with the road.
>yes, but it's very unlikely the paniers are close to your weight, you
>can make a much more impact moving your body,
That's also not true. The panniers don't weigh what a body does, true -
but you can easily have 20 or 30kg there - and they are also much further
from the centre of gravity of a normal bike/rider system than a moved
bottom is, so they affect the CoG proportionately more. It's definitely in
the same ballpark.
>>Bog ordinary cantilevers. You don't need hydraulic discs to make a
>>controller emergency stop at high speeds.
>no you don't but all things being equal they should make a better job of
>it.
You can't make a better job of stopping than stopping with the rear wheel
on the edge of lifting.
>look do you really think that it's a big con and that brakes haven't
>improved over the years?
I certainly think it's partly marketing, but I think the advantages of
discs aren't what you think they are. "Power" is a red herring on solos,
and tandems have not found discs exceptionally powerful.
We've had real advantages of hydraulic disc systems listed. Immunity to
wet muddy conditions; low maintenance (especially no rim wear). And, of
course, if a rider has very weak hands they will get a real benefit from
the reduced application force. But "power"? Not a chance.
>motor vehicals have been useing disks and hydraulic at that for years,
So what? Are you going to put a five-speed gearbox on your bike next?
Just because it fits motorised applications doesn't mean it fits bikes.
--
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|
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Date: 06 Sep 2007 21:54:40
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Somewhere between those two points is a spot or region where it is
> >>easiest, but to say that that's a spot not a region and that that spot
> >>happens to be the amount of force required by the brakes you have _and_
> >>that that will be true for any user is pure guesswork.
> >yes still needs to be some resistance, or it would be too easy to be a
> >system that was on/off
>
> Reducing your guesswork to what it is.
brakes that can be feathered with out having to use any force proper
will be easyer to control, most things requiring fine control try not to
require too much effort.
>
> >>>if your locking managing to lock the wheels at high speeds in the dry
> >>>etc then you either have tires with not enought grip or are not
> >>>countering with your weight. which a hill would help with.
> >>id I say I'd locked the wheels? No.
> >look back at your post not the snippage here, you pritty much did if not
> >in actualality.
>
> Let's see a quote from you that shows it, then. Hint; you can't.
fine
" >2nd at higher speeds you will have a job to lock the wheel, unless you
delbertly unweight a wheel etc."
>This one won't wash with anyone who has made emergency stops downhill
>on
>road. We might not brake as much, but the speeds are higher.
>
if your not saying you lock your wheels at speed then what are you
saying?
> >>But - more than once - descending at speed, with heavy panniers (so with
> >>the overall centre of gravity already lower and to the rear) - I've
> >>had to brake so hard it's finished with the thump of the rear wheel
> >>regaining contact with the road.
> >yes, but it's very unlikely the paniers are close to your weight, you
> >can make a much more impact moving your body,
>
> That's also not true. The panniers don't weigh what a body does, true -
> but you can easily have 20 or 30kg there - and they are also much further
> from the centre of gravity of a normal bike/rider system than a moved
> bottom is, so they affect the CoG proportionately more. It's definitely in
> the same ballpark.
the only limit to how far back and low is rear tire, and saddle more
than enought to be more than 30KG of panniers. particulally as with 30KG
of panniers the possiblt of shifting ones weight much is limited.
>
> >>Bog ordinary cantilevers. You don't need hydraulic discs to make a
> >>controller emergency stop at high speeds.
> >no you don't but all things being equal they should make a better job of
> >it.
>
> You can't make a better job of stopping than stopping with the rear wheel
> on the edge of lifting.
>
correct which is why you need to shift ones' weight back and push that
point to a higher point.
not needed on a tamdem but is on a solo.
> >look do you really think that it's a big con and that brakes haven't
> >improved over the years?
>
> I certainly think it's partly marketing, but I think the advantages of
> discs aren't what you think they are. "Power" is a red herring on solos,
> and tandems have not found discs exceptionally powerful.
>
considering the weight that a tamdem could be, they really should be
useing something a with a lot more bite. even the big disks you like are
still rather light weight.
power isn't a red herring, while it is possible to endo it is also
possible to counter, up to a point, which disks are not at so far.
> We've had real advantages of hydraulic disc systems listed. Immunity to
> wet muddy conditions; low maintenance (especially no rim wear). And, of
> course, if a rider has very weak hands they will get a real benefit from
> the reduced application force. But "power"? Not a chance.
reduced application force is certinaly a real plus in some situations,
very few roads are steep enought to be a issue though tamdems might make
more. but certinaly off road, the differnace from decending down a long
steep hill on cant's or disks can be felt.
and also mean that one doesn't need to put whole hand on lever when you
really should be worring about that rock...
>
> >motor vehicals have been useing disks and hydraulic at that for years,
>
> So what? Are you going to put a five-speed gearbox on your bike next?
> Just because it fits motorised applications doesn't mean it fits bikes.
it means just becuase x number of companies made a balls up of it
doesn't mean there is anything wrong with the underlying idea.
it works else where and very well. on faster heaver vehicals than a
tamdem.
roger
--
www.rogermerriman.com
|
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Date: 06 Sep 2007 22:44:15
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
>>>yes still needs to be some resistance, or it would be too easy to be a
>>>system that was on/off
>>Reducing your guesswork to what it is.
>brakes that can be feathered with out having to use any force proper
>will be easyer to control, most things requiring fine control try not to
>require too much effort.
This is just restating the guesswork. Yes, there's a sweet spot or region
- but you've failed to show that the brakes you personally prefer are in
it or that other designs are outside it - for all possible rider hand
strengths.
>>>look back at your post not the snippage here, you pritty much did if not
>>>in actualality.
>>Let's see a quote from you that shows it, then. Hint; you can't.
>fine
Coo, you're literally minded. But let's see a quote from _me_ that shows I
said it?
>>This one won't wash with anyone who has made emergency stops downhill
>>on road. We might not brake as much, but the speeds are higher.
>if your not saying you lock your wheels at speed then what are you
>saying?
On a good surface what happens first with the front brake - front lock or
rear lift?
>the only limit to how far back and low is rear tire, and saddle more
>than enought to be more than 30KG of panniers.
No. Atop the rear tyre, the very bottom of the weight you shifted is at
the top of where panniers would be.
>particulally as with 30KG
>of panniers the possiblt of shifting ones weight much is limited.
Try reading comprehension; it's either/or. The point is, a rider with
heavy panniers has an overall centre of gravity just as low and rearward
without shifting his weight.
>>You can't make a better job of stopping than stopping with the rear wheel
>>on the edge of lifting.
>correct which is why you need to shift ones' weight back and push that
>point to a higher point.
Try reading comprehension.
>>I certainly think it's partly marketing, but I think the advantages of
>>discs aren't what you think they are. "Power" is a red herring on solos,
>>and tandems have not found discs exceptionally powerful.
>considering the weight that a tamdem could be, they really should be
>useing something a with a lot more bite.
That's sort of the point. There's actually some chance of discovering
which brakes are powerful.
>>We've had real advantages of hydraulic disc systems listed. Immunity to
>>wet muddy conditions; low maintenance (especially no rim wear). And, of
>>course, if a rider has very weak hands they will get a real benefit from
>>the reduced application force. But "power"? Not a chance.
>reduced application force is certinaly a real plus in some situations,
>very few roads are steep enought to be a issue
As I've explained to you several times now, the steeper the road, the
_less_ the maximum braking.
>and also mean that one doesn't need to put whole hand on lever when you
>really should be worring about that rock...
Yes, I worry about rocks with my fingers. Not.
>>So what? Are you going to put a five-speed gearbox on your bike next?
>>Just because it fits motorised applications doesn't mean it fits bikes.
>it works else where and very well. on faster heaver vehicals than a
>tamdem.
I've no doubt a disc system as heavy-duty as those on a motor car would
make a fine brake, if you didn't mind it weighing as much as your bike
did before you fitted it. Of course, it would still be pointless on a solo
because the limit on a solo still isn't braking "power".
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Date: 07 Sep 2007 10:33:12
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >>>yes still needs to be some resistance, or it would be too easy to be a
> >>>system that was on/off
> >>Reducing your guesswork to what it is.
> >brakes that can be feathered with out having to use any force proper
> >will be easyer to control, most things requiring fine control try not to
> >require too much effort.
>
> This is just restating the guesswork. Yes, there's a sweet spot or region
> - but you've failed to show that the brakes you personally prefer are in
> it or that other designs are outside it - for all possible rider hand
> strengths.
>
i don't care if the brakes are disks rims, gas, wire fluid, or what
ever.
what i do care about are brakes that will scrub off speed ie 40 to 50
range and allow one to decend with power left.
> >>>look back at your post not the snippage here, you pritty much did if not
> >>>in actualality.
> >>Let's see a quote from you that shows it, then. Hint; you can't.
> >fine
>
> Coo, you're literally minded. But let's see a quote from _me_ that shows I
> said it?
>
> >>This one won't wash with anyone who has made emergency stops downhill
> >>on road. We might not brake as much, but the speeds are higher.
> >if your not saying you lock your wheels at speed then what are you
> >saying?
>
> On a good surface what happens first with the front brake - front lock or
> rear lift?
>
rear lift normally, hence the need to counter.
> >the only limit to how far back and low is rear tire, and saddle more
> >than enought to be more than 30KG of panniers.
>
> No. Atop the rear tyre, the very bottom of the weight you shifted is at
> the top of where panniers would be.
>
no you get a lot further behind than that. at the end of the ark you
will either hit the very edge of the tire.
> >particulally as with 30KG
> >of panniers the possiblt of shifting ones weight much is limited.
>
> Try reading comprehension; it's either/or. The point is, a rider with
> heavy panniers has an overall centre of gravity just as low and rearward
> without shifting his weight.
with paniers you still have yours truely which is much heaver, far
higher, and forward. which more than makes up for the panniers.
>
> >>You can't make a better job of stopping than stopping with the rear wheel
> >>on the edge of lifting.
> >correct which is why you need to shift ones' weight back and push that
> >point to a higher point.
>
> Try reading comprehension.
>
> >>I certainly think it's partly marketing, but I think the advantages of
> >>discs aren't what you think they are. "Power" is a red herring on solos,
> >>and tandems have not found discs exceptionally powerful.
> >considering the weight that a tamdem could be, they really should be
> >useing something a with a lot more bite.
>
> That's sort of the point. There's actually some chance of discovering
> which brakes are powerful.
>
there is differnce between heat and power.
> >>We've had real advantages of hydraulic disc systems listed. Immunity to
> >>wet muddy conditions; low maintenance (especially no rim wear). And, of
> >>course, if a rider has very weak hands they will get a real benefit from
> >>the reduced application force. But "power"? Not a chance.
> >reduced application force is certinaly a real plus in some situations,
> >very few roads are steep enought to be a issue
>
> As I've explained to you several times now, the steeper the road, the
> _less_ the maximum braking.
yes and as i've pointed out you can very effectvly counter that.
>
> >and also mean that one doesn't need to put whole hand on lever when you
> >really should be worring about that rock...
>
> Yes, I worry about rocks with my fingers. Not.
if your trying to navigate a technical section you will want to keep
most of your fingers on the bars for control not brakes.
>
> >>So what? Are you going to put a five-speed gearbox on your bike next?
> >>Just because it fits motorised applications doesn't mean it fits bikes.
> >it works else where and very well. on faster heaver vehicals than a
> >tamdem.
>
> I've no doubt a disc system as heavy-duty as those on a motor car would
> make a fine brake, if you didn't mind it weighing as much as your bike
> did before you fitted it. Of course, it would still be pointless on a solo
> because the limit on a solo still isn't braking "power".
it wouldn't need to be as heavy weight, but bike brakes are light weight
things, look at the disks very thin, there is a middle ground.
roger
--
www.rogermerriman.com
|
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Date: 07 Sep 2007 18:48:54
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>>if your not saying you lock your wheels at speed then what are you
>>>saying?
>>On a good surface what happens first with the front brake - front lock or
>>rear lift?
>rear lift normally, hence the need to counter.
So I was not saying you lock the wheels. You _made that up_.
>>Try reading comprehension; it's either/or. The point is, a rider with
>>heavy panniers has an overall centre of gravity just as low and rearward
>>without shifting his weight.
>with paniers you still have yours truely which is much heaver, far
>higher, and forward. which more than makes up for the panniers.
Well, no. Panniers weigh less; they're further from the normal centre of
gravity. Works out about the same.
>>>considering the weight that a tamdem could be, they really should be
>>>useing something a with a lot more bite.
>>That's sort of the point. There's actually some chance of discovering
>>which brakes are powerful.
>there is differnce between heat and power.
Yes, and I'm talking about power. Tandems decelerate twice the load and
can decelerate harder.
>>As I've explained to you several times now, the steeper the road, the
>>_less_ the maximum braking.
>yes and as i've pointed out you can very effectvly counter that.
Well, no, you've babbled aimlessly. A given bottom position can also be
used on a shallower slope; once you do that, on the steeper slope, the
maximum braking is... less.
>>I've no doubt a disc system as heavy-duty as those on a motor car would
>>make a fine brake, if you didn't mind it weighing as much as your bike
>>did before you fitted it. Of course, it would still be pointless on a solo
>>because the limit on a solo still isn't braking "power".
>it wouldn't need to be as heavy weight, but bike brakes are light weight
>things, look at the disks very thin, there is a middle ground.
It would still be pointless for the reason above.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Leicesterday, August.
|
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Date: 10 Sep 2007 11:07:32
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>>if your not saying you lock your wheels at speed then what are you
> >>>saying?
> >>On a good surface what happens first with the front brake - front lock or
> >>rear lift?
> >rear lift normally, hence the need to counter.
>
> So I was not saying you lock the wheels. You _made that up_.
>
> >>Try reading comprehension; it's either/or. The point is, a rider with
> >>heavy panniers has an overall centre of gravity just as low and rearward
> >>without shifting his weight.
> >with paniers you still have yours truely which is much heaver, far
> >higher, and forward. which more than makes up for the panniers.
>
> Well, no. Panniers weigh less; they're further from the normal centre of
> gravity. Works out about the same.
can you ladien the paniers so that on the flat with you on the bike, the
bike is at the tipping point? even with the big long hybrid i can make
the front lift by tipping my weight back.
>
> >>>considering the weight that a tamdem could be, they really should be
> >>>useing something a with a lot more bite.
> >>That's sort of the point. There's actually some chance of discovering
> >>which brakes are powerful.
> >there is differnce between heat and power.
>
> Yes, and I'm talking about power. Tandems decelerate twice the load and
> can decelerate harder.
>
> >>As I've explained to you several times now, the steeper the road, the
> >>_less_ the maximum braking.
> >yes and as i've pointed out you can very effectvly counter that.
>
> Well, no, you've babbled aimlessly. A given bottom position can also be
> used on a shallower slope; once you do that, on the steeper slope, the
> maximum braking is... less.
>
it would be a very bad idea to shift one's weight that far as you can
make the bike tip up.
> >>I've no doubt a disc system as heavy-duty as those on a motor car would
> >>make a fine brake, if you didn't mind it weighing as much as your bike
> >>did before you fitted it. Of course, it would still be pointless on a solo
> >>because the limit on a solo still isn't braking "power".
> >it wouldn't need to be as heavy weight, but bike brakes are light weight
> >things, look at the disks very thin, there is a middle ground.
>
> It would still be pointless for the reason above.
roger
--
www.rogermerriman.com
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Date: 10 Sep 2007 14:45:49
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Well, no. Panniers weigh less; they're further from the normal centre of
>>gravity. Works out about the same.
>can you ladien the paniers so that on the flat with you on the bike, the
>bike is at the tipping point?
That's just fore-aft position of centre of gravity; height of centre of
gravity also affects maximum braking.
>>Well, no, you've babbled aimlessly. A given bottom position can also be
>>used on a shallower slope; once you do that, on the steeper slope, the
>>maximum braking is... less.
>it would be a very bad idea to shift one's weight that far as you can
>make the bike tip up.
Not under heavy braking!
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
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5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
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Date: 10 Sep 2007 15:47:58
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Well, no. Panniers weigh less; they're further from the normal centre of
> >>gravity. Works out about the same.
> >can you ladien the paniers so that on the flat with you on the bike, the
> >bike is at the tipping point?
>
> That's just fore-aft position of centre of gravity; height of centre of
> gravity also affects maximum braking.
>
on a bike with out paniers you can get low and rear, such as mountain
bike, you can make a lot of diffenance, you are far and away the
heaviest thing paniers even heavy loaded ones are light in comparison
and have less effect.
i grew up in a steep sided gorge, i'm prefectly aware it's possible to
endo and bike and aware that it's also possible not to, even under hard
braking.
> >>Well, no, you've babbled aimlessly. A given bottom position can also be
> >>used on a shallower slope; once you do that, on the steeper slope, the
> >>maximum braking is... less.
> >it would be a very bad idea to shift one's weight that far as you can
> >make the bike tip up.
>
> Not under heavy braking!
no but it does show that you can move a lot of weight about. down a
steep hill yes you might move a lot but on the flat even under hard
braking it will not be needed as much though some will be needed to
prevent a endo.
roger
--
www.rogermerriman.com
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Date: 10 Sep 2007 17:42:30
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
>>>can you ladien the paniers so that on the flat with you on the bike, the
>>>bike is at the tipping point?
>>That's just fore-aft position of centre of gravity; height of centre of
>>gravity also affects maximum braking.
>on a bike with out paniers you can get low and rear
Maybe you can; but lifting the front wheel doesn't measure "low", just
"rear".
>bike, you can make a lot of diffenance, you are far and away the
>heaviest thing paniers even heavy loaded ones are light in comparison
>and have less effect.
But - as mentioned to you about a million times now - although they are
lighter (but not far and away lighter if heavily laden) - they can be
further from the CoG of the unladen normal-position system.
>>>it would be a very bad idea to shift one's weight that far as you can
>>>make the bike tip up.
>>Not under heavy braking!
>no but it does show that you can move a lot of weight about.
Which is not being disputed. You've lost track of the point in your
semiliterate gibberish.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
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Date: 11 Sep 2007 16:00:36
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >>>can you ladien the paniers so that on the flat with you on the bike, the
> >>>bike is at the tipping point?
> >>That's just fore-aft position of centre of gravity; height of centre of
> >>gravity also affects maximum braking.
> >on a bike with out paniers you can get low and rear
>
> Maybe you can; but lifting the front wheel doesn't measure "low", just
> "rear".
>
the point is the endo, if heavy braking will cause a bike to endo, i'm
pointing out it's possible (upto a point) to counter.
> >bike, you can make a lot of diffenance, you are far and away the
> >heaviest thing paniers even heavy loaded ones are light in comparison
> >and have less effect.
>
> But - as mentioned to you about a million times now - although they are
> lighter (but not far and away lighter if heavily laden) - they can be
> further from the CoG of the unladen normal-position system.
i didn't think the rear rack would take anything like 80KG? most seem to
20/30KG range. which is a long way from even a light person.
>
> >>>it would be a very bad idea to shift one's weight that far as you can
> >>>make the bike tip up.
> >>Not under heavy braking!
> >no but it does show that you can move a lot of weight about.
>
> Which is not being disputed. You've lost track of the point in your
> semiliterate gibberish.
one it is you are disputing at least in your belief that strong brakes
don't matter you'll endo before there any use on a solo.
roger
--
www.rogermerriman.com
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Date: 11 Sep 2007 16:48:31
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Maybe you can; but lifting the front wheel doesn't measure "low", just
>>"rear".
>the point is the endo, if heavy braking will cause a bike to endo, i'm
>pointing out it's possible (upto a point) to counter.
Thank you, Captain Obvious! Perhaps you would like to tell me fire is hot
next?
>>But - as mentioned to you about a million times now - although they are
>>lighter (but not far and away lighter if heavily laden) - they can be
>>further from the CoG of the unladen normal-position system.
>i didn't think the rear rack would take anything like 80KG? most seem to
>20/30KG range. which is a long way from even a light person.
Mine's a Tortec Expedition steel, which is rated to 45kg, and yes, I fill
them full of heavy stuff sometimes. Given that the panniers are also
lower than anyone's getting with bottom contortions, and bottom contortions
don't move your full weight the full distance the bottom moves...
>one it is you are disputing at least in your belief that strong brakes
>don't matter you'll endo before there any use on a solo.
Try again in English.
--
David Damerell <damerell@chiark.greenend.org.uk > flcl?
Today is Stilday, August - a weekend.
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Date: 07 Sep 2007 07:22:07
From: Jon
Subject: Brake dancing [was: Which Brakes? ... ]
|
"Roger Merriman" <NEWS@wodger.demon.co.uk > wrote
>
> what i do care about are brakes that will scrub off speed ie 40 to 50
> range and allow one to decend with power left.
Not sure what "de[s]cend with power left" means.
But it seems to me that there are perhaps some points of agreement:
1) for braking methods that rely on slowing wheel rotations [1],
there is a maximum obtainable deceleration rate on a bicycle
before the rear will lift and rotate around the front contact
point.
2) changing weight distribution (or bicycle geometry) affects that
maximum deceleration rate.
3) going down a hill implicitly shifts the bike and rider weight
distribution forward.
4) the weight distribution downhill cannot be "further back" than
it would be with the same rider position on flat ground, hence
the maximum possible deceleration rate downhill is lower
than on flat.
5) properly designed and adjusted disk and rim bicycle braking
systems, cable and hydraulic, can produce braking force greater
than the maximum possible deceleration rate.
6) braking power above that required to produce the maximum
deceleration rate is irrelevant for how quickly one may stop.
7) [gratuitous ARBC content] long wheelbase recumbent
bikes certainly have a greater maximum potential
deceleration rate than upright bikes.
This says nothing about which system is nicer, easier to use,
maintain, modulate and control, or resists fading, or is better
suited for wet and muddy conditions, etc... Or which one
makes your bike look cool and your friends jealous! %^)
There was recently a very good explanation of the limits
of bicycle braking on the phred touring mailing list. Should
be in the archives at:
http://www.phred.org/mailman/listinfo/touring
It was pointed why it's not a good idea to follow cars at
high speeds too closely on a bicycle. Cars can stop at
much higher deceleration rates than bicycles.
Jon Meinecke
[1] alternative braking methods could include dropping an anchor,
deploying a drag parachute, firing retro-rockets, hitting a large
rock face (with or without a tunnel entrance painted on it), etc...
See Wiley Coyote field tests of Acme Products for examples...
%^)
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Date: 10 Sep 2007 11:07:32
From: Roger Merriman
Subject: Re: Brake dancing [was: Which Brakes? ... ]
|
Jon <jonmein@none.non > wrote:
> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote
> >
> > what i do care about are brakes that will scrub off speed ie 40 to 50
> > range and allow one to decend with power left.
>
> Not sure what "de[s]cend with power left" means.
>
means to decend steep hills as in over 30% at speed with brakes that
will stop rather than just slow.
> But it seems to me that there are perhaps some points of agreement:
>
> 1) for braking methods that rely on slowing wheel rotations [1],
> there is a maximum obtainable deceleration rate on a bicycle
> before the rear will lift and rotate around the front contact
> point.
>
> 2) changing weight distribution (or bicycle geometry) affects that
> maximum deceleration rate.
>
> 3) going down a hill implicitly shifts the bike and rider weight
> distribution forward.
>
> 4) the weight distribution downhill cannot be "further back" than
> it would be with the same rider position on flat ground, hence
> the maximum possible deceleration rate downhill is lower
> than on flat.
>
not entirely get your hanging off the back you can make the bike tip up,
ie endo.
if your used to shifting your weight, you can shift it so the bike will
tip on either end.
> 5) properly designed and adjusted disk and rim bicycle braking
> systems, cable and hydraulic, can produce braking force greater
> than the maximum possible deceleration rate.
>
> 6) braking power above that required to produce the maximum
> deceleration rate is irrelevant for how quickly one may stop.
>
> 7) [gratuitous ARBC content] long wheelbase recumbent
> bikes certainly have a greater maximum potential
> deceleration rate than upright bikes.
>
> This says nothing about which system is nicer, easier to use,
> maintain, modulate and control, or resists fading, or is better
> suited for wet and muddy conditions, etc... Or which one
> makes your bike look cool and your friends jealous! %^)
>
> There was recently a very good explanation of the limits
> of bicycle braking on the phred touring mailing list. Should
> be in the archives at:
>
> http://www.phred.org/mailman/listinfo/touring
>
> It was pointed why it's not a good idea to follow cars at
> high speeds too closely on a bicycle. Cars can stop at
> much higher deceleration rates than bicycles.
>
yes though worth noting they to suffer from weight transfure, even with
sporty set ups the rear's will unweight a fair bit under hard braking.
> Jon Meinecke
>
> [1] alternative braking methods could include dropping an anchor,
> deploying a drag parachute, firing retro-rockets, hitting a large
> rock face (with or without a tunnel entrance painted on it), etc...
>
> See Wiley Coyote field tests of Acme Products for examples...
> %^)
roger
--
www.rogermerriman.com
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Date: 10 Sep 2007 08:43:06
From: Jon
Subject: Re: Brake dancing [was: Which Brakes? ... ]
|
"Roger Merriman" <NEWS@wodger.demon.co.uk > wrote
> Jon <jonmein@none.non> wrote:
>
>> [ points 1-3]
Great! There seems to be some level of implicit agreement on
most points.
>> 4) the weight distribution downhill cannot be "further back" than
>> it would be with the same rider position on flat ground, hence
>> the maximum possible deceleration rate downhill is lower
>> than on flat.
>>
> not entirely get your hanging off the back you can make the bike tip up,
> ie endo.
Do you mean raising the front wheel by shifting weight back? Obviously
this would dramatically reduce front wheel braking effect! %^)
Equally obviously, this point of "wheelie" moves further back under
deceleration. And the fact that you can move further back on a slope
before the point of front wheel lift illustrates that there's less "room
left
to move" to counter decleration forces on a slope. That is, the point
of equalibrium starts further back on a slope. (For some slopes, there
may be enough "leeway" to correct to deceleration *and* slope, but
at no point can you obtain a greater effective weight shift on a slope
than on the flat. Proof is by simple trigonometry.)
>> [...] Cars can stop at
>> much higher deceleration rates than bicycles.
>>
> yes though worth noting they to suffer from weight transfure, even with
> sporty set ups the rear's will unweight a fair bit under hard braking.
Exactly. And the effect for cars is a tendency for the rear to pass the
front by rotating horizonatally (a sideways endo).
Here's a few excerpts from the posting by someone who seems to
have a lot of practical experience in braking and cites references:
George Hall wrote:
Cars and motorcycles can decelerate at a max rate
of about 0.7 - 0.9g.
...
If you only consider the coefficient of friction of tire
rubber on common pavement surfaces, you would
determine that about 0.7 - 0.8g of braking is possible
for a cyclist.
[for cyclists, a] practical limit of about 0.45 - 0.50g is
all that most folks will achieve before they experience
rear wheel liftoff.
[...] caliper brakes, cantilver brakes, V-brakes, or
disc brakes - all of these in normal circumstances can
produce a deceleration of 0.45g - 0.50g [...]
[...] Of course, there are a lot of other considerations
for your individual circumstances and preferences, I'm
only discussing this from the perspective of braking
ability.
http://search.bikelist.org/getmsg.asp?Filename=touring.10709.0118.eml
So points that disk brakes are better for some conditions, that
they feel better, are more responsive, or are easier to maintain,
or sexier, etc.. may all be good reasons for some to chose them!
Or not sufficient reasons for others... YMMV
Disk brakes do complicate some things, for instance, rear rack
mounting for loading touring upright bikes.
Jon
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Date: 11 Sep 2007 16:00:35
From: Roger Merriman
Subject: Re: Brake dancing [was: Which Brakes? ... ]
|
Jon <jonmein@none.non > wrote:
> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote
> > Jon <jonmein@none.non> wrote:
> >
> >> [ points 1-3]
>
> Great! There seems to be some level of implicit agreement on
> most points.
yup.
>
> >> 4) the weight distribution downhill cannot be "further back" than
> >> it would be with the same rider position on flat ground, hence
> >> the maximum possible deceleration rate downhill is lower
> >> than on flat.
> >>
> > not entirely get your hanging off the back you can make the bike tip up,
> > ie endo.
>
> Do you mean raising the front wheel by shifting weight back? Obviously
> this would dramatically reduce front wheel braking effect! %^)
>
quite the point being that you can achive a fairly radical weight shift.
if needed.
> Equally obviously, this point of "wheelie" moves further back under
> deceleration. And the fact that you can move further back on a slope
> before the point of front wheel lift illustrates that there's less "room
> left
> to move" to counter decleration forces on a slope. That is, the point
> of equalibrium starts further back on a slope. (For some slopes, there
> may be enough "leeway" to correct to deceleration *and* slope, but
> at no point can you obtain a greater effective weight shift on a slope
> than on the flat. Proof is by simple trigonometry.)
>
true, that is less room to move, though in pratice even a very steep
road you can get enought weight to prevent endo. off road some slopes
are steep enought you probably can't but thats a mute point as
attempting to brake would probably be foolish.
> >> [...] Cars can stop at
> >> much higher deceleration rates than bicycles.
> >>
> > yes though worth noting they to suffer from weight transfure, even with
> > sporty set ups the rear's will unweight a fair bit under hard braking.
>
> Exactly. And the effect for cars is a tendency for the rear to pass the
> front by rotating horizonatally (a sideways endo).
>
yes can be done though mostly just a slide forward locking the brakes.
> Here's a few excerpts from the posting by someone who seems to
> have a lot of practical experience in braking and cites references:
>
> George Hall wrote:
>
> Cars and motorcycles can decelerate at a max rate
> of about 0.7 - 0.9g.
> ...
>
> If you only consider the coefficient of friction of tire
> rubber on common pavement surfaces, you would
> determine that about 0.7 - 0.8g of braking is possible
> for a cyclist.
>
> [for cyclists, a] practical limit of about 0.45 - 0.50g is
> all that most folks will achieve before they experience
> rear wheel liftoff.
>
> [...] caliper brakes, cantilver brakes, V-brakes, or
> disc brakes - all of these in normal circumstances can
> produce a deceleration of 0.45g - 0.50g [...]
>
> [...] Of course, there are a lot of other considerations
> for your individual circumstances and preferences, I'm
> only discussing this from the perspective of braking
> ability.
>
> http://search.bikelist.org/getmsg.asp?Filename=touring.10709.0118.eml
>
> So points that disk brakes are better for some conditions, that
> they feel better, are more responsive, or are easier to maintain,
> or sexier, etc.. may all be good reasons for some to chose them!
> Or not sufficient reasons for others... YMMV
>
> Disk brakes do complicate some things, for instance, rear rack
> mounting for loading touring upright bikes.
>
> Jon
roger
--
www.rogermerriman.com
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Date: 07 Sep 2007 09:53:08
From: Jon
Subject: Re: Brake dancing [was: Which Brakes? ... ]
|
"Jon" <jonmein@none.non > wrote
> There was recently a very good explanation of the limits
> of bicycle braking on the phred touring mailing list. Should
> be in the archives at:
>
Here's the link to the archived article on bike braking limits
from the touring mailing list
http://search.bikelist.org/getmsg.asp?Filename=touring.10709.0118.eml
Jon
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Date: 04 Sep 2007 10:13:23
From: Ben C
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 2007-09-04, David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
>>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>>Because mountain bikes can't actually use any more braking than any other
>>>solo bike.
>>really? funny the jump though various cable rim brakes to hydraulic
>>disks has been a steady improvement in braking.
>
> No, there hasn't. With a well adjusted cable rim brake you can lift the
> rear wheel (or skid the front on a poor surface). How can a hydraulic disc
> offer more braking than that?
Easily, it might have better power dissipation and therefore not
overheat and become useless after prolonged and/or repeated use.
Think about car brakes. Just about any car will do an emergency stop
from 30mph without the brakes overheating; but drive fast for 30 miles
on twisty roads and many cars will start to suffer brake fade as things
get too hot.
Any brake that's merely half-decent should be able to lift the back
wheel on demand. It doesn't end there.
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Date: 05 Sep 2007 17:12:19
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Ben C <spamspam@spam.eggs >:
>On 2007-09-04, David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>No, there hasn't. With a well adjusted cable rim brake you can lift the
>>rear wheel (or skid the front on a poor surface). How can a hydraulic disc
>>offer more braking than that?
>Easily, it might have better power dissipation and therefore not
>overheat and become useless after prolonged and/or repeated use.
Right. And what's got more heat capacity, a small metal disc or a large
metal rim? What's got more surface area?
Read the earlier thread; we started talking about tandems, where
overheating actually is an issue.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
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Date: 05 Sep 2007 13:12:17
From: Ben C
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 2007-09-05, David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Ben C <spamspam@spam.eggs>:
>>On 2007-09-04, David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>>No, there hasn't. With a well adjusted cable rim brake you can lift the
>>>rear wheel (or skid the front on a poor surface). How can a hydraulic disc
>>>offer more braking than that?
>>Easily, it might have better power dissipation and therefore not
>>overheat and become useless after prolonged and/or repeated use.
>
> Right. And what's got more heat capacity, a small metal disc or a large
> metal rim?
Does heat capacity help much?
I suppose I could attempt the math...
Aluminium has an SHC of 0.897 J/gK according to Wikipedia.
A rim weighs about 500g. So how much energy to raise its temperature
from 20C to 100C, on the assumption that 100C is very hot for a bicycle
rim (is that figure about right?)
500 * 0.897 * 80 = 35880J
So 35880J can be soaked up in the rim before it gets to 100C. That
corresponds to what change in speed of a 100kg bike+rider?
E = 0.5*m*v^2
sqrt(2E/m) = v
sqrt((2 * 35880) / 100) = 27m/s, or 97kph.
This seems to be saying that even if the rim doesn't manage to lose
_anything_ to the air, you can still brake to a stop from 97kph (using
only one brake) and not get the rim hotter than 100C.
Of course this is cumulative, so ten 10kph retardations, with no loss to
the air, would cause the same buildup.
I think this probably explains why dissipation to the air isn't terribly
significant for one-off emergency stops, but is for repeated braking
during a long descent.
Anyway, I couldn't see steel's SHC on Wikipedia but some other website
suggested it might be around 0.5 J/gK but it depends on the kind of
steel. A disk weighs around 170g.
170 * 0.5 * 80 = 6800J
sqrt((2 * 6800) / 100) = 12m/s or 43kph
So quite a bit worse it would seem. That's only four 10kph retardations
before the disk reaches 100C (assuming zero dissipation to the air).
> What's got more surface area?
In the case of bicycle disks, a rim I should think, since the disks are
usually so filigreed and of course have smaller diameter.
I'm starting to wonder why disk overheating isn't a big problem with the
lower heat capacity and probably lower dissipation rate to the air.
Perhaps the operating temperature range of a disk is higher as I
suggested earlier. I pulled this figure of 100C out of the air as "high"
for a rim brake, but perhaps they don't really get that hot. A disk on
the other hand can probably afford to get a bit hotter than that-- the
fluid won't boil until perhaps 170C. If the disk is hotter then its
dissipation to the air will be better (bigger temperature gradient).
|
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Date: 06 Sep 2007 09:39:46
From: Dave Larrington
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
In news:slrnfdtsbi.a4p.spamspam@bowser.marioworld,
Ben C <spamspam@spam.eggs > tweaked the Babbage-Engine to tell us:
> I'm starting to wonder why disk overheating isn't a big problem with
> the lower heat capacity and probably lower dissipation rate to the
> air. Perhaps the operating temperature range of a disk is higher as I
> suggested earlier. I pulled this figure of 100C out of the air as
> "high" for a rim brake, but perhaps they don't really get that hot. A
> disk on the other hand can probably afford to get a bit hotter than
> that-- the fluid won't boil until perhaps 170C.
A bit of googling suggests that the boiling point of DOT5.1 brake fluid is
about 260 deg. C. The mineral oils used in Magura systems, and LHM used by
the parsimonious instead of the Magura stuff, seems to be in the same
region.
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk >
Hoc ardur vincere docet.
|
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Date: 06 Sep 2007 04:41:43
From: Ben C
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 2007-09-06, Dave Larrington <smert.spamionam@privacy.net > wrote:
> In news:slrnfdtsbi.a4p.spamspam@bowser.marioworld,
> Ben C <spamspam@spam.eggs> tweaked the Babbage-Engine to tell us:
>
>> I'm starting to wonder why disk overheating isn't a big problem with
>> the lower heat capacity and probably lower dissipation rate to the
>> air. Perhaps the operating temperature range of a disk is higher as I
>> suggested earlier. I pulled this figure of 100C out of the air as
>> "high" for a rim brake, but perhaps they don't really get that hot. A
>> disk on the other hand can probably afford to get a bit hotter than
>> that-- the fluid won't boil until perhaps 170C.
>
> A bit of googling suggests that the boiling point of DOT5.1 brake fluid is
> about 260 deg. C. The mineral oils used in Magura systems, and LHM used by
> the parsimonious instead of the Magura stuff, seems to be in the same
> region.
Yes, although I also got that "perhaps 170C" from a bit of googling. The
page I found made a distinction between "wet" and "dry" boiling points,
"wet" being what you get when your brake fluid has absorbed 3% of water.
Here it is: http://www.afcoracing.com/tech_pages/fluid.shtml
I went for the "wet" boiling point of DOT 4 since I heard somewhere else
that bicycle brake fluid boils much more easily than the car stuff
(although it strips the paint less).
Brake fluid should never boil in a car unless it's very old. You should
be able to get the pads practically on fire before the fluid boils. But
I have heard tell of fluid boiling occurring with MTB disks, implying to
me that the stuff people are putting in boils at a rather lower temp
than DOT4 or DOT5.1.
Dry for DOT5.1 is 288 deg C according to them.
Anyway you can get special paint for testing this. You get three or four
colour-coded paints with different, known melting points. You dab a
series of spots on the disk somewhere they won't get in the way, take
your favourite MTB route down Mont Blanc, and see which spots have
melted.
|
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Date: 06 Sep 2007 12:57:05
From: Dave Larrington
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
In news:slrnfdviq8.5gt.spamspam@bowser.marioworld,
Ben C <spamspam@spam.eggs > tweaked the Babbage-Engine to tell us:
> Yes, although I also got that "perhaps 170C" from a bit of googling.
> The page I found made a distinction between "wet" and "dry" boiling
> points, "wet" being what you get when your brake fluid has absorbed
> 3% of water.
>
> Here it is: http://www.afcoracing.com/tech_pages/fluid.shtml
>
> I went for the "wet" boiling point of DOT 4 since I heard somewhere
> else that bicycle brake fluid boils much more easily than the car
> stuff (although it strips the paint less).
>
> Brake fluid should never boil in a car unless it's very old. You
> should be able to get the pads practically on fire before the fluid
> boils. But I have heard tell of fluid boiling occurring with MTB
> disks, implying to me that the stuff people are putting in boils at a
> rather lower temp than DOT4 or DOT5.1.
>
> Dry for DOT5.1 is 288 deg C according to them.
I use DOT 5.1 from Halfrauds in all my hydraulic discs and can't recall any
problems which might have been caused by boiling fluid. This is 99.9%
on-road, admittedly, but even try to keep a recumbent down to a sane speed
on a steep wet twisty downhill in the middle of the night using only the
rear brake[1] it's been OK.
1 - the front one decided to lose interest after a minor off - no sign of a
fluid leak and rebleeding seems to have restored normal functionality.
Colour me baffled.
--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk >
Apparently Guy has now got a Brompton. I'd never have guessed.
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Date: 06 Sep 2007 08:10:32
From: Ben C
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 2007-09-06, Dave Larrington <smert.spamionam@privacy.net > wrote:
> In news:slrnfdviq8.5gt.spamspam@bowser.marioworld,
> Ben C <spamspam@spam.eggs> tweaked the Babbage-Engine to tell us:
>
>> Yes, although I also got that "perhaps 170C" from a bit of googling.
>> The page I found made a distinction between "wet" and "dry" boiling
>> points, "wet" being what you get when your brake fluid has absorbed
>> 3% of water.
>>
>> Here it is: http://www.afcoracing.com/tech_pages/fluid.shtml
>>
>> I went for the "wet" boiling point of DOT 4 since I heard somewhere
>> else that bicycle brake fluid boils much more easily than the car
>> stuff (although it strips the paint less).
>>
>> Brake fluid should never boil in a car unless it's very old. You
>> should be able to get the pads practically on fire before the fluid
>> boils. But I have heard tell of fluid boiling occurring with MTB
>> disks, implying to me that the stuff people are putting in boils at a
>> rather lower temp than DOT4 or DOT5.1.
>>
>> Dry for DOT5.1 is 288 deg C according to them.
>
>
> I use DOT 5.1 from Halfrauds in all my hydraulic discs and can't recall any
> problems which might have been caused by boiling fluid. This is 99.9%
> on-road, admittedly, but even try to keep a recumbent down to a sane speed
> on a steep wet twisty downhill in the middle of the night using only the
> rear brake[1] it's been OK.
Yes I think you'd have a hard time boiling DOT 5.1 in anything, which is
as it should be. Boiling brake fluid is not something you file under
"acceptable".
> 1 - the front one decided to lose interest after a minor off - no sign of a
> fluid leak and rebleeding seems to have restored normal functionality.
> Colour me baffled.
Perhaps it got a gulp of air into the lines when it was upside down.
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Date: 05 Sep 2007 19:42:00
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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Quoting Ben C <spamspam@spam.eggs >:
>I think this probably explains why dissipation to the air isn't terribly
>significant for one-off emergency stops, but is for repeated braking
>during a long descent.
So far, so good.
>Anyway, I couldn't see steel's SHC on Wikipedia but some other website
>suggested it might be around 0.5 J/gK but it depends on the kind of
>steel. A disk weighs around 170g.
I must admit, shamefully, I quite forgot the question of which material
we were using.
>I'm starting to wonder why disk overheating isn't a big problem with the
>lower heat capacity and probably lower dissipation rate to the air.
>Perhaps the operating temperature range of a disk is higher as I
>suggested earlier.
That's certainly true, but we're conflating two issues here. It's fair to
say that discs don't suffer as badly from overheating in the sense that a
catastrophic failure will occur at a much higher temperature, so much
higher that (I guess) this more than offsets the effect of their lower
heat capacity. But the question asked was about brake fade - and, given
that disc pads aren't made of anything magic, if anything they'll suffer
_that_ first because they get hotter faster.
[Of course, they don't, but I think that's because brake fade with heat is
not a serious issue on either type of brake, as opposed to drum brakes...]
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
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Date: 05 Sep 2007 22:03:41
From: Alan Braggins
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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In article <4lA*E47Tr@news.chiark.greenend.org.uk >, David Damerell wrote:
>heat capacity. But the question asked was about brake fade - and, given
>that disc pads aren't made of anything magic, if anything they'll suffer
>_that_ first because they get hotter faster.
They might not be magic, but nor are they they same material as
rim brake pads, so they could still resist fade better.
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Date: 05 Sep 2007 19:23:37
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Ben C" <spamspam@spam.eggs > wrote in message
news:slrnfdtsbi.a4p.spamspam@bowser.marioworld...
> I'm starting to wonder why disk overheating isn't a big problem with the
> lower heat capacity and probably lower dissipation rate to the air.
> Perhaps the operating temperature range of a disk is higher as I
> suggested earlier. I pulled this figure of 100C out of the air as "high"
> for a rim brake, but perhaps they don't really get that hot. A disk on
> the other hand can probably afford to get a bit hotter than that-- the
> fluid won't boil until perhaps 170C. If the disk is hotter then its
> dissipation to the air will be better (bigger temperature gradient).
Yup, that's pretty much it. It's quite easy to get a drum brake to the
temperature where water merrily boils away when sprayed onto it - discs
aren't that different. Can't remember if I've got rims to that point -
definitely too hot to touch, but a precise answer is harder.
cheers,
clive
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Date: 05 Sep 2007 19:24:31
From: _
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On Wed, 5 Sep 2007 19:23:37 +0100, Clive George wrote:
> "Ben C" <spamspam@spam.eggs> wrote in message
> news:slrnfdtsbi.a4p.spamspam@bowser.marioworld...
>
>> I'm starting to wonder why disk overheating isn't a big problem with the
>> lower heat capacity and probably lower dissipation rate to the air.
>> Perhaps the operating temperature range of a disk is higher as I
>> suggested earlier. I pulled this figure of 100C out of the air as "high"
>> for a rim brake, but perhaps they don't really get that hot. A disk on
>> the other hand can probably afford to get a bit hotter than that-- the
>> fluid won't boil until perhaps 170C. If the disk is hotter then its
>> dissipation to the air will be better (bigger temperature gradient).
>
> Yup, that's pretty much it. It's quite easy to get a drum brake to the
> temperature where water merrily boils away when sprayed onto it - discs
> aren't that different. Can't remember if I've got rims to that point -
> definitely too hot to touch, but a precise answer is harder.
>
There is research out there on the inter-webby-thing showing rim brakes
reaching something like 175-200 degrees farrenheit, and coaster-brakes
reaching (depending on the part measured) around 800 degrees.
The enrgy has to go somewhere, and that somewhere eventually is the air
around the wheel. The pad and surface heat up; the heat is transmitted to
the air. The rates of heating and of tranmission determine the temperture
reached - a larger dissipative area, all else being equal, will reach a
lower temperature.
A typical cycle rim has around 150 inches of area exposed to the air. How
much area does a typical hub-brake-disc have?
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Date: 05 Sep 2007 15:08:53
From: Ben C
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On 2007-09-05, _ <jtayNOSPAMlor@hfDONTSENDMESPAMx.andara.com > wrote:
> On Wed, 5 Sep 2007 19:23:37 +0100, Clive George wrote:
>
>> "Ben C" <spamspam@spam.eggs> wrote in message
>> news:slrnfdtsbi.a4p.spamspam@bowser.marioworld...
>>
>>> I'm starting to wonder why disk overheating isn't a big problem with the
>>> lower heat capacity and probably lower dissipation rate to the air.
>>> Perhaps the operating temperature range of a disk is higher as I
>>> suggested earlier. I pulled this figure of 100C out of the air as "high"
>>> for a rim brake, but perhaps they don't really get that hot. A disk on
>>> the other hand can probably afford to get a bit hotter than that-- the
>>> fluid won't boil until perhaps 170C. If the disk is hotter then its
>>> dissipation to the air will be better (bigger temperature gradient).
>>
>> Yup, that's pretty much it. It's quite easy to get a drum brake to the
>> temperature where water merrily boils away when sprayed onto it - discs
>> aren't that different. Can't remember if I've got rims to that point -
>> definitely too hot to touch, but a precise answer is harder.
>>
>
> There is research out there on the inter-webby-thing showing rim brakes
> reaching something like 175-200 degrees farrenheit, and coaster-brakes
> reaching (depending on the part measured) around 800 degrees.
>
> The enrgy has to go somewhere, and that somewhere eventually is the air
> around the wheel. The pad and surface heat up; the heat is transmitted to
> the air. The rates of heating and of tranmission determine the temperture
> reached - a larger dissipative area, all else being equal, will reach a
> lower temperature.
In a given amount of time-- eventually they will both reach the
temperature of the surrounding air.
But the other point is that the greater the temperature gradient, the
greater the rate of dissipation.
I think rate of dissipation is proportional both to temperature
difference and to area.
http://www.spiraxsarco.com/resources/steam-engineering-tutorials/steam-engineering-principles-and-heat-transfer/heat-transfer.asp
> A typical cycle rim has around 150 inches of area exposed to the air. How
> much area does a typical hub-brake-disc have?
It's about 1/4 the radius, and I think therefore about 1/4 the area
because in both cases the brake track area is something like
circumference * a few cm.
If the disk was a complete disk it would be more, but most of them
consist of a slender spider's web arrangement supporting a sort of
"rim". Perhaps that rim is a bit deeper than the wheel rim, so there
could be as much as 1/2 the area. And the spider's web bit will make a
small contribution.
I wonder if the spider's web is also intended to insulate the hot disk
from the hub where it would start cooking the grease. That and to look
cool and like it's saving a few grams (which also reduces the
effectiveness as a heat sink).
Anyway, if the disk is 1/4 the area of a rim but operates at four times
the temperature it ought to dissipate at the same rate.
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Date: 05 Sep 2007 20:58:27
From: _
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Wed, 05 Sep 2007 15:08:53 -0500, Ben C wrote:
> On 2007-09-05, _ <jtayNOSPAMlor@hfDONTSENDMESPAMx.andara.com> wrote:
>> On Wed, 5 Sep 2007 19:23:37 +0100, Clive George wrote:
>>
>>> "Ben C" <spamspam@spam.eggs> wrote in message
>>> news:slrnfdtsbi.a4p.spamspam@bowser.marioworld...
>>>
>>>> I'm starting to wonder why disk overheating isn't a big problem with the
>>>> lower heat capacity and probably lower dissipation rate to the air.
>>>> Perhaps the operating temperature range of a disk is higher as I
>>>> suggested earlier. I pulled this figure of 100C out of the air as "high"
>>>> for a rim brake, but perhaps they don't really get that hot. A disk on
>>>> the other hand can probably afford to get a bit hotter than that-- the
>>>> fluid won't boil until perhaps 170C. If the disk is hotter then its
>>>> dissipation to the air will be better (bigger temperature gradient).
>>>
>>> Yup, that's pretty much it. It's quite easy to get a drum brake to the
>>> temperature where water merrily boils away when sprayed onto it - discs
>>> aren't that different. Can't remember if I've got rims to that point -
>>> definitely too hot to touch, but a precise answer is harder.
>>>
>>
>> There is research out there on the inter-webby-thing showing rim brakes
>> reaching something like 175-200 degrees farrenheit, and coaster-brakes
>> reaching (depending on the part measured) around 800 degrees.
>>
>> The enrgy has to go somewhere, and that somewhere eventually is the air
>> around the wheel. The pad and surface heat up; the heat is transmitted to
>> the air. The rates of heating and of tranmission determine the temperture
>> reached - a larger dissipative area, all else being equal, will reach a
>> lower temperature.
>
> In a given amount of time-- eventually they will both reach the
> temperature of the surrounding air.
>
> But the other point is that the greater the temperature gradient, the
> greater the rate of dissipation.
>
> I think rate of dissipation is proportional both to temperature
> difference and to area.
>
> http://www.spiraxsarco.com/resources/steam-engineering-tutorials/steam-engineering-principles-and-heat-transfer/heat-transfer.asp
>
>> A typical cycle rim has around 150 inches of area exposed to the air. How
>> much area does a typical hub-brake-disc have?
>
> It's about 1/4 the radius, and I think therefore about 1/4 the area
> because in both cases the brake track area is something like
> circumference * a few cm.
On a cycle rim you also have the rest of the rim contiguous with the
braking track - giving a much larger dissipative area.
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Date: 04 Sep 2007 15:34:39
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> No, there hasn't. With a well adjusted cable rim brake you can lift the
> rear wheel (or skid the front on a poor surface). How can a hydraulic disc
> offer more braking than that? It can't.
TIt isn't the *more* it offers you from locking, it's the fine control
of /ever so slightly less/ than locking which is easier with the more
sensitive feel of a hydraulic.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 05 Sep 2007 17:09:41
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>No, there hasn't. With a well adjusted cable rim brake you can lift the
>>rear wheel (or skid the front on a poor surface). How can a hydraulic disc
>>offer more braking than that? It can't.
>TIt isn't the *more* it offers you from locking,
You have excised the quoted context where I say;
"Because mountain bikes can't actually use any more braking than any other
solo bike" and Roger Merriman disputes that specific claim.
I know you want to leap back on the fingertips hobbyhorse but that's not
what I'm talking about there.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
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Date: 03 Sep 2007 21:20:55
From: Steve Gravrock
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On 2007-09-03, Roger Merriman <NEWS@wodger.demon.co.uk > wrote:
> David Damerell <damerell@chiark.greenend.org.uk> wrote:
>
>> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
>> >which begs the other question if tamdems have allways or for a reasonble
>> >time had half decent brakes why did it not filter to mountain bikes?
>>
>> Because mountain bikes can't actually use any more braking than any other
>> solo bike.
>
> really? funny the jump though various cable rim brakes to hydraulic
> disks has been a steady improvement in braking.
It's been a steady improvement in the mechanical advantage of the brake
system, and thus a drop in how much hand pressure you need to get the
same braking, but the total deceleration you can manage is still limited
by going over the bars rather than by any property of the brakes.
Or, to put it differently, properly set up cantilevers will stop you
just as well on a given slope as hydraulic discs. The difference is in
how sore your hands will be at the bottom.
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Date: 04 Sep 2007 14:06:04
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Steve Gravrock wrote:
> Or, to put it differently, properly set up cantilevers will stop you
> just as well on a given slope as hydraulic discs. The difference is in
> how sore your hands will be at the bottom.
And also in how easy it is to fine tune the braking so you have as much
force as possible /without locking the wheels/. The fine control is
much easier if you're not pulling so hard.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 04 Sep 2007 13:16:53
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Steve Gravrock <usenet@sdg.users.panix.com > wrote:
> On 2007-09-03, Roger Merriman <NEWS@wodger.demon.co.uk> wrote:
> > David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >
> >> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >> >which begs the other question if tamdems have allways or for a reasonble
> >> >time had half decent brakes why did it not filter to mountain bikes?
> >>
> >> Because mountain bikes can't actually use any more braking than any other
> >> solo bike.
> >
> > really? funny the jump though various cable rim brakes to hydraulic
> > disks has been a steady improvement in braking.
>
> It's been a steady improvement in the mechanical advantage of the brake
> system, and thus a drop in how much hand pressure you need to get the
> same braking, but the total deceleration you can manage is still limited
> by going over the bars rather than by any property of the brakes.
>
that as maybe certinaly at slower speeds, but ramp the speed up to and
disks do seem to stop one faster and cleaner then rim brakes, the rim
did stop the bike and safely, but at higher speeds they don't at least
in my experiance attaully stop as fast.
> Or, to put it differently, properly set up cantilevers will stop you
> just as well on a given slope as hydraulic discs. The difference is in
> how sore your hands will be at the bottom.
yes that is one point, that cant's need a harder tug. but also given a
steep enought hill don't stop as well as hydraulic disks. around SW
london and surrrey the hills that are about don't stress the brakes
enought for this to be a issue. get to proper hills and the differnce
becomes very apparent.
roger
--
www.rogermerriman.com
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Date: 04 Sep 2007 07:52:01
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Steve Gravrock said the following on 03/09/2007 22:20:
> Or, to put it differently, properly set up cantilevers will stop you
> just as well on a given slope as hydraulic discs. The difference is in
> how sore your hands will be at the bottom.
The difference is that you might not always want to stop on a given
slope, but have delicate control going down it. Less likely on a
tandem, but on an MTB pointing down a 60 degree loose slope you need
very precise braking control :-)
--
Paul Boyd
http://www.paul-boyd.co.uk/
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Date: 04 Sep 2007 03:01:00
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Paul Boyd <usenet.is.worse@plusnet > wrote in
news:13dq0724878dhac@corp.supernews.com:
>
> Less likely on a
> tandem, but on an MTB pointing down a 60 degree loose slope you need
> very precise braking control :-)
>
<pedant >
You can't have a 60 degree loose slope - its beyond the maximum angle of
repose for loose material.
</pedant >
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 04 Sep 2007 10:08:38
From: Alan Braggins
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
In article <Xns99A15BB5D75E1TR@216.196.109.145 >, Tony Raven wrote:
>Paul Boyd <usenet.is.worse@plusnet> wrote in
>news:13dq0724878dhac@corp.supernews.com:
>>
>> Less likely on a
>> tandem, but on an MTB pointing down a 60 degree loose slope you need
>> very precise braking control :-)
>
><pedant>
>You can't have a 60 degree loose slope - its beyond the maximum angle of
>repose for loose material.
></pedant>
I think you might reasonably consider damp sand to be a loose slope for
the purpose of riding a bike down it, even though it obviously isn't as
loose as dry sand (which is why it has a much higher angle of repose).
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Date: 04 Sep 2007 14:24:03
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
armb@chiark.greenend.org.uk (Alan Braggins) wrote in
news:slrnfdq84m.o0a.armb@chiark.greenend.org.uk:
>>>
>>> Less likely on a
>>> tandem, but on an MTB pointing down a 60 degree loose slope you need
>>> very precise braking control :-)
>>
>><pedant>
>>You can't have a 60 degree loose slope - its beyond the maximum angle of
>>repose for loose material.
>></pedant>
>
> I think you might reasonably consider damp sand to be a loose slope for
> the purpose of riding a bike down it, even though it obviously isn't as
> loose as dry sand (which is why it has a much higher angle of repose).
>
It would have to never dry out to stay there and how it got there in that
state in the first place would be an interesting story.
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 05 Sep 2007 08:24:23
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Tony Raven wrote:
> It would have to never dry out to stay there and how it got there in that
> state in the first place would be an interesting story.
I direct m'lud's attention to the nearest sand dunes for plenty of sand
cliff-ettes which are loose enough to be easily pulled away with hands
but are steep enough that kids much enjoy sailing over them to the nice
soft landings beyond.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 05 Sep 2007 02:32:50
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Peter Clinch <p.j.clinch@dundee.ac.uk > wrote in
news:5k73skF2cqlqU1@mid.individual.net:
> Tony Raven wrote:
>
>> It would have to never dry out to stay there and how it got there in
>> that state in the first place would be an interesting story.
>
> I direct m'lud's attention to the nearest sand dunes for plenty of
> sand cliff-ettes which are loose enough to be easily pulled away with
> hands but are steep enough that kids much enjoy sailing over them to
> the nice soft landings beyond.
>
I would refer my honourable friend to Exhibits 1 on the geology of sand
dunes where the maximum angle is 30-34 degrees on the steep side.
Exhibit 1: http://www2.nature.nps.gov/geology/usgsnps/dune/dune.html
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 05 Sep 2007 08:40:01
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Tony Raven wrote:
> I would refer my honourable friend to Exhibits 1 on the geology of sand
> dunes where the maximum angle is 30-34 degrees on the steep side.
> Exhibit 1: http://www2.nature.nps.gov/geology/usgsnps/dune/dune.html
Having a geology degree I am well aware of that, /but/ that's a free
dune with no vegetation, and the "no vegetation" bit is most important
(as any Dutch flood engineer will tell you, and why they tend their
coastal dunes very carefully!). I'm quite sure you've been to dunes by
the UK sea-side with practically vertical small sections, and a walk
along many river banks will often reveal similar structures well over 34
degrees that will easily fall to pieces with a little encouragement.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 05 Sep 2007 02:47:34
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Peter Clinch <p.j.clinch@dundee.ac.uk > wrote in news:5k74puF2eca8U1
@mid.individual.net:
> Tony Raven wrote:
>
>> I would refer my honourable friend to Exhibits 1 on the geology of sand
>> dunes where the maximum angle is 30-34 degrees on the steep side.
>> Exhibit 1: http://www2.nature.nps.gov/geology/usgsnps/dune/dune.html
>
> Having a geology degree I am well aware of that, /but/ that's a free
> dune with no vegetation, and the "no vegetation" bit is most important
> (as any Dutch flood engineer will tell you, and why they tend their
> coastal dunes very carefully!). I'm quite sure you've been to dunes by
> the UK sea-side with practically vertical small sections, and a walk
> along many river banks will often reveal similar structures well over 34
> degrees that will easily fall to pieces with a little encouragement.
>
I stand corrected then but going back to the OP, do you think the situation
of "on an MTB pointing down a 60 degree loose slope you need very precise
braking control" is realistic. I recognise there are 60 degree slopes but
there is unlikely to be any loose material on them and I somehow doubt the
rear wheel would stay down if you tried to brake.
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 05 Sep 2007 09:18:13
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Tony Raven wrote:
> I stand corrected then but going back to the OP, do you think the situation
> of "on an MTB pointing down a 60 degree loose slope you need very precise
> braking control" is realistic. I recognise there are 60 degree slopes but
> there is unlikely to be any loose material on them and I somehow doubt the
> rear wheel would stay down if you tried to brake.
I can see such a slope existing if one takes "loose" as "stuck on... but
not at all well, and not enough to stay put when a bike hits it", but
I'd agree that anyone going down 60 degree slopes on a bike is pretty
much wasting their time with the brakes! 60 degrees is actually typical
of lower grade rock climbing, and IME people very often over-estimate
true steepness of steep slopes (where "steep" starts at about 20 degrees).
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 05 Sep 2007 11:44:05
From: Ace
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Wed, 05 Sep 2007 09:18:13 +0100, Peter Clinch
<p.j.clinch@dundee.ac.uk > wrote:
>I'd agree that anyone going down 60 degree slopes on a bike is pretty
>much wasting their time with the brakes! 60 degrees is actually typical
>of lower grade rock climbing, and IME people very often over-estimate
>true steepness of steep slopes (where "steep" starts at about 20 degrees).
Same happens in skiing - many people will overestimate the angle of
slope they've just skied, and the main reason isn't one of boasting,
but just that it _feels_ like that. In practice, marked runs over
40degrees are very rare, although I know a couple that I have
personally measured at 42=43deg. I have a clinometer needle on my
compass which can amuse or embarrass folk who will insist that the
slope's steeper than it really is.
As for 'loose' material on such a steep slope - we're taught in
avalanche training that slopes above 55deg are outside the danger
angles, as it's not possible for enough snow to accumulate on them.
38deg is normally accepted as the most dangerous angle, as this is the
maximum slope that a truly granular substance will stick to.
--
Ace in Alsace - brucedotrogers a.t rochedotcom
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Date: 05 Sep 2007 05:12:20
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Ace <seesig@virgin.net > wrote in news:8ktsd35r1us5kqm3b8rgbc2gtllb1uimi5@
4ax.com:
> On Wed, 05 Sep 2007 09:18:13 +0100, Peter Clinch
> <p.j.clinch@dundee.ac.uk> wrote:
>
>> [...]
>
> Same happens in skiing - many people will overestimate the angle of
> slope they've just skied, and the main reason isn't one of boasting,
> but just that it _feels_ like that. In practice, marked runs over
> 40degrees are very rare, although I know a couple that I have
> personally measured at 42=43deg. I have a clinometer needle on my
> compass which can amuse or embarrass folk who will insist that the
> slope's steeper than it really is.
Saudan's Couloir/Couloir Extreme in Blackcomb is reputedly 50 degrees and a
marked double diamond run. It feels vertical but they run an annual GS
race down it.
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 05 Sep 2007 11:01:46
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Ace wrote:
> As for 'loose' material on such a steep slope - we're taught in
> avalanche training that slopes above 55deg are outside the danger
> angles, as it's not possible for enough snow to accumulate on them.
You need to be careful about qualifying assumptions like that... how
about a convex slope where the bottom is too steep for accumulation, but
the top isn't?
Friends of mine have been caught in a cornice collapse in a gully where
loose snow wasn't accumulating, but was unfortunately passing through at
some speed :-(
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 05 Sep 2007 12:09:51
From: Ace
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
On Wed, 05 Sep 2007 11:01:46 +0100, Peter Clinch
<p.j.clinch@dundee.ac.uk > wrote:
>Ace wrote:
>
>> As for 'loose' material on such a steep slope - we're taught in
>> avalanche training that slopes above 55deg are outside the danger
>> angles, as it's not possible for enough snow to accumulate on them.
>
>You need to be careful about qualifying assumptions like that... how
>about a convex slope where the bottom is too steep for accumulation, but
>the top isn't?
Oh yes, you're quite right - clearly one needs to be looking at the
slope above you as well as the bit you're planning to ski on.
>Friends of mine have been caught in a cornice collapse in a gully where
>loose snow wasn't accumulating, but was unfortunately passing through at
>some speed :-(
Known as a "terrain trap". Hope they weren't hurt.
--
Ace in Alsace - brucedotrogers a.t rochedotcom
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Date: 05 Sep 2007 11:27:54
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Ace wrote:
> Known as a "terrain trap". Hope they weren't hurt.
Not terminally, but one heel smashed into enough pieces to never be
quite right again and a leg broken well enough to acquire some bonus
titanium :-(
I ended up helping the MRT a year later where the same thing had
happened to a group in exactly the same place (Cinderella Gully on Craeg
Smeggy) just before I was passing, which was a broken ankle on one and
chipped vertebrae on another.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 03 Sep 2007 04:48:56
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
NEWS@wodger.demon.co.uk (Roger Merriman) wrote in
news:1i3utrf.1u1ejivhmpn9wN%NEWS@wodger.demon.co.uk:
>
>> [...]
> which begs the other question if tamdems have allways or for a reasonble
> time had half decent brakes why did it not filter to mountain bikes?
> racing bikes i can get as weight etc.
>
You can fit an Arai drag brake to you mountain bike if you want but its the
wrong sort of tool. On tandems they have been used for years to scrub off
the main speed on downhills in a "constantly on" mode with the normal
brakes used to do the rest.
http://www.precisiontandems.com/arai.htm
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 03 Sep 2007 12:19:53
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Tony Raven <junk@raven-family.invalid > wrote:
> NEWS@wodger.demon.co.uk (Roger Merriman) wrote in
> news:1i3utrf.1u1ejivhmpn9wN%NEWS@wodger.demon.co.uk:
> >
> >> [...]
> > which begs the other question if tamdems have allways or for a reasonble
> > time had half decent brakes why did it not filter to mountain bikes?
> > racing bikes i can get as weight etc.
> >
>
> You can fit an Arai drag brake to you mountain bike if you want but its the
> wrong sort of tool. On tandems they have been used for years to scrub off
> the main speed on downhills in a "constantly on" mode with the normal
> brakes used to do the rest.
> http://www.precisiontandems.com/arai.htm
indeed, the chances of attaully heating a rim or disk on normal bike
seem slim. and attaully looking and tamdems they seem to have bog
standurd brakes, mostly V brakes with the drum to assist. does also beg
the question if heat is a problem then why use the rim with the risks
that come with that. but use a disk where if it gets hot it shouldn't
cause any problems bar brake fade.
does suggest that braking is heat rather than stronger brakes, for the
tamdems.
roger
--
www.rogermerriman.com
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Date: 04 Sep 2007 16:51:49
From: dabac
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta HydraulicDisc?
|
Roger Merriman Wrote:
> ...indeed, the chances of attaully heating a rim or a disk on a normal
> bike seem slim.
For your average flatland commute - yes, for riding in mountainous
terrain - no. After I'd done a rapid descent of 1000 meters or so water
was actually sizzling around the rim when I rolled through a puddle at
the bottom of the slope.
--
dabac
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Date: 03 Sep 2007 17:29:20
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>standurd brakes, mostly V brakes with the drum to assist. does also beg
>the question if heat is a problem then why use the rim with the risks
>that come with that. but use a disk where if it gets hot it shouldn't
>cause any problems bar brake fade.
Or the disc warping, the hydraulic fluid boiling, plastic bits catching on
fire... yes, Santana produced all these failure modes in disc brakes.
>does suggest that braking is heat rather than stronger brakes, for the
>tamdems.
Stronger brakes as well. For the same deceleration a tandem brake is
working twice as hard, and a tandem can manage higher decelerations than
any solo.
The real answer is that what people think of as "strong" brakes aren't.
_Any_ sensible design of brake can lift the rear wheel (or skid the front
wheel on a poor surface). For solo bikes there is no difference in brake
strength from one design to another.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 03 Sep 2007 20:24:15
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >standurd brakes, mostly V brakes with the drum to assist. does also beg
> >the question if heat is a problem then why use the rim with the risks
> >that come with that. but use a disk where if it gets hot it shouldn't
> >cause any problems bar brake fade.
>
> Or the disc warping, the hydraulic fluid boiling, plastic bits catching on
> fire... yes, Santana produced all these failure modes in disc brakes.
>
still a disk failing has to be safer than a tire blowing off?
which then begs the question why the standard v brakes with out issue
then?
> >does suggest that braking is heat rather than stronger brakes, for the
> >tamdems.
>
> Stronger brakes as well. For the same deceleration a tandem brake is
> working twice as hard, and a tandem can manage higher decelerations than
> any solo.
>
> The real answer is that what people think of as "strong" brakes aren't.
> _Any_ sensible design of brake can lift the rear wheel (or skid the front
> wheel on a poor surface). For solo bikes there is no difference in brake
> strength from one design to another.
that is not my experance at least given enought, speed and/or gradiant.
the differnce can be quite a lot.
roger
--
www.rogermerriman.com
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Date: 04 Sep 2007 15:07:39
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Or the disc warping, the hydraulic fluid boiling, plastic bits catching on
>>fire... yes, Santana produced all these failure modes in disc brakes.
>still a disk failing has to be safer than a tire blowing off?
Neither is an acceptable outcome.
>which then begs the question why the standard v brakes with out issue
>then?
Please look up "begs the question" to find out what it means.
V-brakes (alone) on a tandem have the difficulty that they will blow off
tyres, so they are not without issue.
>>The real answer is that what people think of as "strong" brakes aren't.
>>_Any_ sensible design of brake can lift the rear wheel (or skid the front
>>wheel on a poor surface). For solo bikes there is no difference in brake
>>strength from one design to another.
>that is not my experance at least given enought, speed and/or gradiant.
If you can't lift the rear wheel, adjust your brakes properly. Note that a
downhill gradient makes this easier, not harder.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Second Saturday, August - a weekend.
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Date: 04 Sep 2007 16:19:26
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Or the disc warping, the hydraulic fluid boiling, plastic bits catching on
> >>fire... yes, Santana produced all these failure modes in disc brakes.
> >still a disk failing has to be safer than a tire blowing off?
>
> Neither is an acceptable outcome.
true.
>
> >which then begs the question why the standard v brakes with out issue
> >then?
>
> Please look up "begs the question" to find out what it means.
>
> V-brakes (alone) on a tandem have the difficulty that they will blow off
> tyres, so they are not without issue.
if they are not with out issue they why are tamdems being sold with
them? and very pricey ones at that?
>
> >>The real answer is that what people think of as "strong" brakes aren't.
> >>_Any_ sensible design of brake can lift the rear wheel (or skid the front
> >>wheel on a poor surface). For solo bikes there is no difference in brake
> >>strength from one design to another.
> >that is not my experance at least given enought, speed and/or gradiant.
>
> If you can't lift the rear wheel, adjust your brakes properly. Note that a
> downhill gradient makes this easier, not harder.
yes if don't shift my weight back, but shifting ones weight back, can be
very effective. you can get a lot of braking out of the rear by doing
that well.
roger
--
www.rogermerriman.com
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Date: 05 Sep 2007 17:05:12
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>V-brakes (alone) on a tandem have the difficulty that they will blow off
>>tyres, so they are not without issue.
>if they are not with out issue they why are tamdems being sold with
>them? and very pricey ones at that?
You will find those are not intended for anything like loaded touring
or additionally have a drum or disc [1] brake intended for use as a
drag brake. For example, a racing tandem doesn't have these issues.
>>If you can't lift the rear wheel, adjust your brakes properly. Note that a
>>downhill gradient makes this easier, not harder.
>yes if don't shift my weight back, but shifting ones weight back, can be
>very effective.
Wrong again. Regardless of shifting weight, a downhill gradient makes it
easier to lift the rear wheel.
[1] optimistically.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 06 Sep 2007 10:29:06
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>V-brakes (alone) on a tandem have the difficulty that they will blow off
> >>tyres, so they are not without issue.
> >if they are not with out issue they why are tamdems being sold with
> >them? and very pricey ones at that?
>
> You will find those are not intended for anything like loaded touring
> or additionally have a drum or disc [1] brake intended for use as a
> drag brake. For example, a racing tandem doesn't have these issues.
>
maybe so but seems plenty about. which seems a odd saving when the
tamdem can be the price of a new car.
but yes from what you've said (and others) and just plain comman sence.
ie how well would those tamdems cope with two large men let alone their
gear...warm i guess at best.
i can see that Santana have spent a lot of time and effort into tamdem
brakes. consdering the possible weight, that still looks quite under
powered when you consider the weights.
> >>If you can't lift the rear wheel, adjust your brakes properly. Note that a
> >>downhill gradient makes this easier, not harder.
> >yes if don't shift my weight back, but shifting ones weight back, can be
> >very effective.
>
> Wrong again. Regardless of shifting weight, a downhill gradient makes it
> easier to lift the rear wheel.
>
if you don't shift your weight about yes, the greatest possiblity for a
endo is the emergency stop on the flat as you will be luckly to beable
to shift your weight fully, in the time it takes to stop.
decending a hill even a hill over 30% at least on a mountain bike you
can get a lot of weight over the rear, if fact going the other way i can
un weigh the rear enought to start to scrabble on the tarmack. i do
though acknowedge that one growing up in a steep sided gorge i'm used to
shifting one's weight around for hills, and that a mountain bike is
easyer to do that than on road bike.
> [1] optimistically.
roger
--
www.rogermerriman.com
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Date: 06 Sep 2007 16:21:13
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>You will find those are not intended for anything like loaded touring
>>or additionally have a drum or disc [1] brake intended for use as a
>>drag brake. For example, a racing tandem doesn't have these issues.
>maybe so but seems plenty about. which seems a odd saving when the
>tamdem can be the price of a new car.
It's also a large weight saving. The Arai brake, which is the only really
effective solution for long descents, weighs a ton because it's a giant
heatsink.
>i can see that Santana have spent a lot of time and effort into tamdem
>brakes. consdering the possible weight, that still looks quite under
>powered when you consider the weights.
But your perceptions of brake "power" are worthless because every decent
design of brake has exactly the same stopping power on a solo.
>>Wrong again. Regardless of shifting weight, a downhill gradient makes it
>>easier to lift the rear wheel.
>if you don't shift your weight about yes,
What I say remains accurate. It's elementary mechanics.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
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Date: 06 Sep 2007 18:01:29
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>You will find those are not intended for anything like loaded touring
> >>or additionally have a drum or disc [1] brake intended for use as a
> >>drag brake. For example, a racing tandem doesn't have these issues.
> >maybe so but seems plenty about. which seems a odd saving when the
> >tamdem can be the price of a new car.
>
> It's also a large weight saving. The Arai brake, which is the only really
> effective solution for long descents, weighs a ton because it's a giant
> heatsink.
>
consdering that the weight of a tamdem can be fairly impressive ie in
the folks, thus two big men + gear and thats a whole lot of trouble.
> >i can see that Santana have spent a lot of time and effort into tamdem
> >brakes. consdering the possible weight, that still looks quite under
> >powered when you consider the weights.
>
> But your perceptions of brake "power" are worthless because every decent
> design of brake has exactly the same stopping power on a solo.
>
maybe in paper, but taking my old cant bike away from the rolling downs
and to the beacons shows that while it's brakes can cope with the soft
lumps of the south east. proper hills it lacks the power, compared with
a newer bike with disks.
> >>Wrong again. Regardless of shifting weight, a downhill gradient makes it
> >>easier to lift the rear wheel.
> >if you don't shift your weight about yes,
>
> What I say remains accurate. It's elementary mechanics.
within a very tight artifial peramitors yes. if you shift your postion
and weight the rear is quite useable. even down very steep gradient's
roger
--
www.rogermerriman.com
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Date: 06 Sep 2007 20:18:03
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>But your perceptions of brake "power" are worthless because every decent
>>design of brake has exactly the same stopping power on a solo.
>maybe in paper,
And in elementary mechanics.
>but taking my old cant bike away from the rolling downs
>and to the beacons shows that while it's brakes can cope with the soft
>lumps of the south east. proper hills it lacks the power, compared with
>a newer bike with disks.
Which is still rubbish because an increasing downhill gradient _reduces_
the maximum deceleration.
>>>>Wrong again. Regardless of shifting weight, a downhill gradient makes it
>>>>easier to lift the rear wheel.
>>>if you don't shift your weight about yes,
>>What I say remains accurate. It's elementary mechanics.
>within a very tight artifial peramitors yes. if you shift your postion
>and weight the rear is quite useable. even down very steep gradient's
Which is also still rubbish as anyone can determine with heavy panniers.
30kg in panniers shifts the centre of gravity more than you can by moving
your bottom; and with 30kg in panniers you can still lift the rear wheel
under braking; and a downhill gradient still reduces the maximum
deceleration before that happens.
You're just clinging to purely psychosomatic ideas of brake power. It
won't wash; and particularly it won't wash with anyone familiar with
tandem applications, where you actually _can_ produce differences in brake
power.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Date: 06 Sep 2007 21:54:39
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>But your perceptions of brake "power" are worthless because every decent
> >>design of brake has exactly the same stopping power on a solo.
> >maybe in paper,
>
> And in elementary mechanics.
i'm sure it terms of heat they are much of a muchness. and yes if you
don't move at point X the bike will endo.
>
> >but taking my old cant bike away from the rolling downs
> >and to the beacons shows that while it's brakes can cope with the soft
> >lumps of the south east. proper hills it lacks the power, compared with
> >a newer bike with disks.
>
> Which is still rubbish because an increasing downhill gradient _reduces_
> the maximum deceleration.
>
yes if i sit on the saddle and just jank the brake, but most will learn
to get out of the saddle and use that weight.
> >>>>Wrong again. Regardless of shifting weight, a downhill gradient makes it
> >>>>easier to lift the rear wheel.
> >>>if you don't shift your weight about yes,
> >>What I say remains accurate. It's elementary mechanics.
> >within a very tight artifial peramitors yes. if you shift your postion
> >and weight the rear is quite useable. even down very steep gradient's
>
> Which is also still rubbish as anyone can determine with heavy panniers.
> 30kg in panniers shifts the centre of gravity more than you can by moving
> your bottom; and with 30kg in panniers you can still lift the rear wheel
> under braking; and a downhill gradient still reduces the maximum
> deceleration before that happens.
yes of coarse a hill will increase a heavly laden bikes endo point, but
you weigh a lot more than 30KG and on some bikes you can move that
weight around a lot, not just a minor shift, that is one reason Mountain
bikes don't allways have the sadle up high so that weight can be
shifted. you can get suprisingly low and far back, the limit is the
sadle and the rear tire.
>
> You're just clinging to purely psychosomatic ideas of brake power. It
> won't wash; and particularly it won't wash with anyone familiar with
> tandem applications, where you actually _can_ produce differences in brake
> power.
try taking a bike up and down steep hills good 30% shift your weight
around by that i don't mean your bottom as you put it, but bodly get
right back as far as you can go and as far forward. you may be suprised.
roger
--
www.rogermerriman.com
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Date: 06 Sep 2007 22:23:05
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
>>>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>>>But your perceptions of brake "power" are worthless because every decent
>>>>design of brake has exactly the same stopping power on a solo.
>>>maybe in paper,
>>And in elementary mechanics.
>i'm sure it terms of heat they are much of a muchness. and yes if you
>don't move at point X the bike will endo.
And for a given bottom position, every design of brake has the same
stopping power.
>>>but taking my old cant bike away from the rolling downs
>>>and to the beacons shows that while it's brakes can cope with the soft
>>>lumps of the south east. proper hills it lacks the power, compared with
>>>a newer bike with disks.
>>Which is still rubbish because an increasing downhill gradient _reduces_
>>the maximum deceleration.
>yes if i sit on the saddle and just jank the brake, but most will learn
>to get out of the saddle and use that weight.
Doesn't matter. If you can brake on the those soft lumps, you can manage
the deceleration possible on proper hills because it _is less_.
>>Which is also still rubbish as anyone can determine with heavy panniers.
>>30kg in panniers shifts the centre of gravity more than you can by moving
>>your bottom; and with 30kg in panniers you can still lift the rear wheel
>>under braking; and a downhill gradient still reduces the maximum
>>deceleration before that happens.
>yes of coarse a hill will increase a heavly laden bikes endo point, but
>you weigh a lot more than 30KG and on some bikes you can move that
>weight around a lot,
You can move _some_ of that weight around a lot; your arms and legs don't
move so much for a given bottom shift. And when we say "a lot", it's not a
lot compared to the distance that rear panniers are below and to the rear
of the saddle.
>>You're just clinging to purely psychosomatic ideas of brake power. It
>>won't wash; and particularly it won't wash with anyone familiar with
>>tandem applications, where you actually _can_ produce differences in brake
>>power.
>try taking a bike up and down steep hills good 30%
When the gradient gets steep enough, the available braking before endo is
small regardless of bottom position. That's one reason it's so blindingly
obvious you're taking rubbish; you're picking the worse case for a brake
to demonstrate supposedly superior power.
>shift your weight around by that i don't mean your bottom as you put it
Yes, you do. Your hands won't move; your shoulders won't get any further
from the handlebars than they are with straight arms, although they will
drop a bit. Your feet aren't going anywhere. The bottom is exactly the
part that moves a lot.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace
|
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Date: 07 Sep 2007 10:33:12
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
David Damerell <damerell@chiark.greenend.org.uk > wrote:
> Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
> >>>David Damerell <damerell@chiark.greenend.org.uk> wrote:
> >>>>But your perceptions of brake "power" are worthless because every decent
> >>>>design of brake has exactly the same stopping power on a solo.
> >>>maybe in paper,
> >>And in elementary mechanics.
> >i'm sure it terms of heat they are much of a muchness. and yes if you
> >don't move at point X the bike will endo.
>
> And for a given bottom position, every design of brake has the same
> stopping power.
yes but you'll have a job realising that. you will not beable to pull
the levers hard enought.
you can get to the point that the bike will not endo how ever hard you
pull the brakes.
>
> >>>but taking my old cant bike away from the rolling downs
> >>>and to the beacons shows that while it's brakes can cope with the soft
> >>>lumps of the south east. proper hills it lacks the power, compared with
> >>>a newer bike with disks.
> >>Which is still rubbish because an increasing downhill gradient _reduces_
> >>the maximum deceleration.
> >yes if i sit on the saddle and just jank the brake, but most will learn
> >to get out of the saddle and use that weight.
>
> Doesn't matter. If you can brake on the those soft lumps, you can manage
> the deceleration possible on proper hills because it _is less_.
>
no it's perfectly possible to counter. it isn't hard at all.
> >>Which is also still rubbish as anyone can determine with heavy panniers.
> >>30kg in panniers shifts the centre of gravity more than you can by moving
> >>your bottom; and with 30kg in panniers you can still lift the rear wheel
> >>under braking; and a downhill gradient still reduces the maximum
> >>deceleration before that happens.
> >yes of coarse a hill will increase a heavly laden bikes endo point, but
> >you weigh a lot more than 30KG and on some bikes you can move that
> >weight around a lot,
>
> You can move _some_ of that weight around a lot; your arms and legs don't
> move so much for a given bottom shift. And when we say "a lot", it's not a
> lot compared to the distance that rear panniers are below and to the rear
> of the saddle.
>
on a bike with out rider yes, but a heavily panniered bike will have a
rider when moving, and is likely to be a lot heaver, higher and more
forward, reduceing the benfit of the paniers. with regard to endos
> >>You're just clinging to purely psychosomatic ideas of brake power. It
> >>won't wash; and particularly it won't wash with anyone familiar with
> >>tandem applications, where you actually _can_ produce differences in brake
> >>power.
> >try taking a bike up and down steep hills good 30%
>
> When the gradient gets steep enough, the available braking before endo is
> small regardless of bottom position. That's one reason it's so blindingly
> obvious you're taking rubbish; you're picking the worse case for a brake
> to demonstrate supposedly superior power.
i'm not i'm pointing out that it is possible to counter the endo and
that riding up and down steep hills doesn't not mean that you end up
endoing every time you have to do a emergecy brake.
>
> >shift your weight around by that i don't mean your bottom as you put it
>
> Yes, you do. Your hands won't move; your shoulders won't get any further
> from the handlebars than they are with straight arms, although they will
> drop a bit. Your feet aren't going anywhere. The bottom is exactly the
> part that moves a lot.
on a mountain bike your shoulder will be above and just behind the
handle bars, you can move your shoulder to just above the saddle very
few hills if any would need such a move. your hands and feet stay put
but you can mover your trunk in a ark down and behind. which puts a lot
of weight lower down and rear.
roger
--
www.rogermerriman.com
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Date: 07 Sep 2007 18:44:50
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Quoting Roger Merriman <NEWS@wodger.demon.co.uk >:
>David Damerell <damerell@chiark.greenend.org.uk> wrote:
>>Quoting Roger Merriman <NEWS@wodger.demon.co.uk>:
>>And for a given bottom position, every design of brake has the same
>>stopping power.
>yes but you'll have a job realising that. you will not beable to pull
>the levers hard enought.
Also rubbish, and a particularly worthless piece of rubbish to produce to
me when you know I ride tandem. Our centre of gravity's far further back
than you can produce with any contortions in the saddle; I can brake
harder than any solo. Hand strength is not the limiting factor.
>on a bike with out rider yes, but a heavily panniered bike will have a
>rider when moving, and is likely to be a lot heaver, higher and more
>forward, reduceing the benfit of the paniers. with regard to endos
Reading comprehension again. The point is, the CoG of "normal rider
position, heavy panniers" is as far back and down as "abnormal rider
position".
>>When the gradient gets steep enough, the available braking before endo is
>>small regardless of bottom position. That's one reason it's so blindingly
>>obvious you're taking rubbish; you're picking the worse case for a brake
>>to demonstrate supposedly superior power.
>i'm not
Yes, you are; the steeper the hill, the less the braking before an endo.
--
David Damerell <damerell@chiark.greenend.org.uk > Kill the tomato!
Today is Leicesterday, August.
|
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Date: 04 Sep 2007 17:17:41
From: dabac
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta HydraulicDisc?
|
Roger Merriman Wrote:
> ...which then begs the question why the standard v brakes with ou
> issue then?
It's probably due to something we might call "user profile". Of all th
people who owns tandems, not many really use them for serious touring
They get bought for a laugh, for some sedate riding together with
less bike minded SO and similar reasons. For these guys, the majorit
of tandem owners, the V-brake is just fine. Those who really want to g
somewhere with their tandems end up customizing/improving their bikes t
various degrees
--
dabac
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Date: 03 Sep 2007 15:34:20
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
NEWS@wodger.demon.co.uk (Roger Merriman) wrote in
news:1i3vrac.12wh6fh3la53jN%NEWS@wodger.demon.co.uk:
> still a disk failing has to be safer than a tire blowing off?
>
> which then begs the question why the standard v brakes with out issue
> then?
>
I've had a front tyre blow explosively (not from heating) on a tandem doing
about 30mph downhill on a fire road. Because a tandem has a long wheelbase
it was relatively easy to bring it to a halt. I would much rather go
through that any time than have the brakes fail at that speed on a slope
for which the only answer would be a painful bale out.
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
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Date: 04 Sep 2007 08:45:17
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Tony Raven <junk@raven-family.invalid > wrote:
> NEWS@wodger.demon.co.uk (Roger Merriman) wrote in
> news:1i3vrac.12wh6fh3la53jN%NEWS@wodger.demon.co.uk:
>
> > still a disk failing has to be safer than a tire blowing off?
> >
> > which then begs the question why the standard v brakes with out issue
> > then?
> >
>
> I've had a front tyre blow explosively (not from heating) on a tandem doing
> about 30mph downhill on a fire road. Because a tandem has a long wheelbase
> it was relatively easy to bring it to a halt. I would much rather go
> through that any time than have the brakes fail at that speed on a slope
> for which the only answer would be a painful bale out.
i'm suprised you didn't have more problems but then i guess the extra
stablity of a tamdem helps.
roger
--
www.rogermerriman.com
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Date: 03 Sep 2007 06:55:39
From: Tony Raven
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
NEWS@wodger.demon.co.uk (Roger Merriman) wrote in
news:1i3v58y.5ykd2y1onief8N%NEWS@wodger.demon.co.uk:
> Tony Raven <junk@raven-family.invalid> wrote:
>
>> [...]
>
> indeed, the chances of attaully heating a rim or disk on normal bike
> seem slim.
Not slim at all on a long descent
> and attaully looking and tamdems they seem to have bog
> standurd brakes, mostly V brakes with the drum to assist. does also beg
> the question if heat is a problem then why use the rim with the risks
> that come with that. but use a disk where if it gets hot it shouldn't
> cause any problems bar brake fade.
>
> does suggest that braking is heat rather than stronger brakes, for the
> tamdems.
>
You can use disks but you need them designed for tandem heat loads that
most of them are not. A disk could not be used with a drum on the rear
wheel because the drum takes up the disk space - so you are going to need
a rim brake on the back anyway - unlike singles rear brakes are effective
on tandems. So that leaves you with just a front disk.
--
Tony
" I would never die for my beliefs because I might be wrong."
Bertrand Russell
|
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Date: 03 Sep 2007 15:42:47
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Tony Raven <junk@raven-family.invalid > wrote:
> NEWS@wodger.demon.co.uk (Roger Merriman) wrote in
> news:1i3v58y.5ykd2y1onief8N%NEWS@wodger.demon.co.uk:
>
> > Tony Raven <junk@raven-family.invalid> wrote:
> >
> >> [...]
> >
> > indeed, the chances of attaully heating a rim or disk on normal bike
> > seem slim.
>
> Not slim at all on a long descent
okay not something i've ever had a problem with but then the geography
means you don't tend to get long fast descents but short and sharp.
ie it might be over 30% or more in places but you'll reach the bottom
before the heat of the rim starts to be a issue.
>
> > and attaully looking and tamdems they seem to have bog
> > standurd brakes, mostly V brakes with the drum to assist. does also beg
> > the question if heat is a problem then why use the rim with the risks
> > that come with that. but use a disk where if it gets hot it shouldn't
> > cause any problems bar brake fade.
> >
> > does suggest that braking is heat rather than stronger brakes, for the
> > tamdems.
> >
>
> You can use disks but you need them designed for tandem heat loads that
> most of them are not. A disk could not be used with a drum on the rear
> wheel because the drum takes up the disk space - so you are going to need
> a rim brake on the back anyway - unlike singles rear brakes are effective
> on tandems. So that leaves you with just a front disk.
ah righty that kinda makes sence. i guess that disks big enought to
disapate the heat would start to get seriously heavy. as car and
motorbike disks are.
roger
--
www.rogermerriman.com
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Date: 03 Sep 2007 12:37:21
From: Paul Boyd
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Roger Merriman said the following on 03/09/2007 12:19:
> indeed, the chances of attaully heating a rim or disk on normal bike
> seem slim.
Are you serious?
--
Paul Boyd
http://www.paul-boyd.co.uk/
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Date: 31 Aug 2007 15:16:50
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
David Damerell wrote:
> This is typical of this sort of discussion. What starts as an unqualified
> "X is best" turns out to be "X is best off-road on a Sunday with your
> underpants on your head", or whatever else doesn't fit the experience of
> whoever is replying.
>
> Why not _mention_ that from the start?
I use my hydraulic brakes on the road. Though they do get off road,
it's only as far as I get with a recumbent tourer, which isn't serious
off-road and only by way of getting to another road.
And I use them because IME they are a lot nicer in use than cable
brakes, and I didn't think they would be any better until I tried them,
and it was trying them that caused me to buy some.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
|
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Date: 31 Aug 2007 19:43:02
From: David Damerell
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
Quoting Peter Clinch <p.j.clinch@dundee.ac.uk >:
>David Damerell wrote:
>>This is typical of this sort of discussion. What starts as an unqualified
>>"X is best" turns out to be "X is best off-road on a Sunday with your
>>underpants on your head", or whatever else doesn't fit the experience of
>>whoever is replying.
>I use my hydraulic brakes on the road.
Right, but I was responding to Roger Merriman, whose "hydraulic brakes
stop you getting tired hands" (which is bunk) has morphed into "hydraulic
brakes stop you getting tired hands off-road" (which might well be bunk,
but I wouldn't know).
--
David Damerell <damerell@chiark.greenend.org.uk > Distortion Field!
Today is Second Tuesday, August.
|
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Date: 31 Aug 2007 00:27:59
From: Clive George
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
"Roger Merriman" <NEWS@wodger.demon.co.uk > wrote in message
news:1i3ood8.1350ga83fid1oN%NEWS@wodger.demon.co.uk...
> the road that drops from the havard down to though to crickhowel is
> fairly steep one and long and yet even that you only get slight i'm
> useing the brakes a bit feel not a attaully twinge. unlike off road
> where decending with old bikes and old brakes by the time you'd reached
> the bottom you can feel it in your forearms, if you mostly ride on road
> then you not need to brake for as long nor as hard
I find it's the bumpiness which gives the grief, not the hanging on to the
brakes per se. Hanging onto both the bars and the brakes gives my arms a
harder time than just the bars on their own.
>> [1] on a long line between LE and JOG.
>
> not a acronym i know sorry.
Blimey, you've been around here long enough. Traditional ends of this island
of ours.
cheers,
clive
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Date: 31 Aug 2007 11:18:48
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Clive George <clive@xxxx-x.fsnet.co.uk > wrote:
> "Roger Merriman" <NEWS@wodger.demon.co.uk> wrote in message
> news:1i3ood8.1350ga83fid1oN%NEWS@wodger.demon.co.uk...
>
> > the road that drops from the havard down to though to crickhowel is
> > fairly steep one and long and yet even that you only get slight i'm
> > useing the brakes a bit feel not a attaully twinge. unlike off road
> > where decending with old bikes and old brakes by the time you'd reached
> > the bottom you can feel it in your forearms, if you mostly ride on road
> > then you not need to brake for as long nor as hard
>
> I find it's the bumpiness which gives the grief, not the hanging on to the
> brakes per se. Hanging onto both the bars and the brakes gives my arms a
> harder time than just the bars on their own.
yes off road that is the issue, and why good brakes make all the
differnance but there are some roads that are steep enought that you
have to pull the leavers hard enought that you can feel it in your
forearms the old tram road out of brynmawr which follows along along the
clydach gorge, at it's end essently plumits down to crickhowel.
<http://www.bikely.com/maps/bike-path/clydach-gorge > check out the
elvation profile, you really can't miss the hill!
but essently i agree with you for most rides you feel it in your legs
not your arms. very few hills are steep enought.
>
> >> [1] on a long line between LE and JOG.
> >
> > not a acronym i know sorry.
>
> Blimey, you've been around here long enough. Traditional ends of this island
> of ours.
>
acronym's are something of blind spot here.
> cheers,
> clive
roger
--
www.rogermerriman.com
|
| | |
Date: 29 Aug 2007 09:57:02
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
|
roger merriman wrote:
> Thing is though that locking the wheels is one thing, stopping fast
> and safely is another, my cheap hybrid can lock it's wheels, but i
> would regard is brakes as poor, in that it wouldn't stop in hurry at
> speed, while my moutain bikes will, which considering the rubber on
> the road i'd probably struggle to lock wheels up.
Indeed. And this is where hydraulics are better IMHO, as they let you
have high power combined with very sensitive fingertip control.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
|
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Date: 30 Aug 2007 16:16:14
From: Roger Merriman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
|
Peter Clinch <p.j.clinch@dundee.ac.uk > wrote:
> roger merriman wrote:
>
> > Thing is though that locking the wheels is one thing, stopping fast
> > and safely is another, my cheap hybrid can lock it's wheels, but i
> > would regard is brakes as poor, in that it wouldn't stop in hurry at
> > speed, while my moutain bikes will, which considering the rubber on
> > the road i'd probably struggle to lock wheels up.
>
> Indeed. And this is where hydraulics are better IMHO, as they let you
> have high power combined with very sensitive fingertip control.
>
> Pete.
the big thing for me is certinaly off road and back in wales is being
able to brake with out having to strain at the leavers so i can use a
softer more controlled brake thus keeping the braking smoother etc.
roger
--
www.rogermerriman.com
|
| |
Date: 28 Aug 2007 22:03:00
From: Tom \Johnny Sunset\ Sherman
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Artemisia wrote:
> I've been assuming all along that the brakes I would get on my new HPV
> Scorpion would be the Magura Big Hydraulic disc. I made this assumption
> because in the _Greenspeed_ customisation guide, these are given as the
> best choice for heavy riders in terms of max stopping power and subtlety
> of control. Greenspeed, unlike HPV, doesn't offer either the Martas or
> the Avids.
>
> Now I've been reading up on the competition, and have become confused.
> The Avid mechanical brakes are what come as standard. I've done some
> googling on these and have found the most incredibly consistent series
> of rave reviews. The consensus out there seems to be - people who fork
> out extra for hydraulic discs are plain stupid or misguided, the Avids
> are so good as to be unbeatable on function at a much lower price and
> much easier maintenance.
>
> I also learn that hydraulic brakes have brake fluid which can leak, and
> that they are a lot fiddlier to maintain, and a lot more delicate and
> likely to fail. Is this true?
>
> And does anyone know the difference between the Martas and the Bigs?
> What justifies the extra price on the Martas?
>
> I'm not quibbling on price. I will pay _whatever_is_necessary_ to get
> the product that is best for _me_. I will be using this trike to get
> down the very steep hills on my commute to work. I have never been able
> to bike these descents and have trouble even walking them, such is the
> angle. There is about a km of dizzying descent, crossed with traffic
> intersections. I _must_ be confident that I can stop.
>
> But simplicity of maintenance is as important as powerful stopping. The
> other vocation of the trike will be to come touring with me in places
> where support may not be easily found, and to be on and off planes and
> trains. If hydraulic disks are too delicate, and by failing immobilize
> the entire vehicle, then they may not justify their extra cost.
>
> Thanks for your experiences. Cheers,
I can lock up both from wheels on dry pavement with the Avid mechanical
disc brakes on my trike. The feel is mushy compared to a good hydraulic
system, however.
--
Tom Sherman - Holstein-Friesland Bovinia
A Real Cyclist [TM] keeps at least one bicycle in the bedroom.
--
Posted via a free Usenet account from http://www.teranews.com
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Date: 28 Aug 2007 21:37:09
From: Duncan Smith
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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>
> But simplicity of maintenance is as important as powerful stopping. The
> other vocation of the trike will be to come touring with me in places
> where support may not be easily found, and to be on and off planes and
> trains. If hydraulic disks are too delicate, and by failing immobilize
> the entire vehicle, then they may not justify their extra cost.
>
I've had an Avid mech bb7 on the front of my (non-recumb.) road bike
for the best part of a year. It's got plenty of stopping power, even
when fully laden with panniers, etc., and I trust it enough not to
bother with a rear brake. I haven't had to go near the cable
adjustment yet - the only servicing I do is to spray and wipe down the
pads/rotor with fluid and do some minor adjustment to the pads with
the speed dial every now and again - maybe once a fortnight or so.
Quite happy with them so far.
Regards,
Duncan
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Date: 28 Aug 2007 21:21:06
From: Peter Clinch
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Artemisia wrote:
> Now I've been reading up on the competition, and have become confused.
> The Avid mechanical brakes are what come as standard. I've done some
> googling on these and have found the most incredibly consistent series
> of rave reviews. The consensus out there seems to be - people who fork
> out extra for hydraulic discs are plain stupid or misguided, the Avids
> are so good as to be unbeatable on function at a much lower price and
> much easier maintenance.
All mechanical brakes suffer from gradual degradation as the cables
clag up and corrode. A brand new set of mechanical brakes feels
great, but that's because they're brand new. Come back in two
years and then try again, and the hydraulics will still work much
as the day you started and the mechanicals quite possibly won't.
I've used the Avids on the Kinetics demo HPVels and they were...
okay. OTOH, every time I've used hydraulics I've come away feeling
they're much better in use than mechanicals. I traded my
Streetmachines mechanical rim brakes for hydraulics, and that is
one upgrade I have never regretted for a second, even though I've
done big tours quite happily with the original Vs.
Much easier maintenance on mechanicals? Can't really see it
myself... my hydraulic brakes have been as close to fit and forget
as a bike component gets. I need to replace the pads (very easy on
HS-33s, don't know about the various discs), and that's it.
> I also learn that hydraulic brakes have brake fluid which can leak, and
> that they are a lot fiddlier to maintain, and a lot more delicate and
> likely to fail. Is this true?
They have fluid and technically it /can/ leak, but mine don't.
Doesn't seem to bother the vast majority of cars on the road
either. Fiddlier to maintain, would be dependent on
implementation. IME hydraulic systems are certainly no fiddlier
intrinsically to maintain than mechanicals, and need a lot less
fettling to start with. A lot more delicate sounds like crap to
me: these things are used on downhill racing mountain bikes, *not*
an arena where delicacy and failure are really options that would
endear them to competitors...
> And does anyone know the difference between the Martas and the Bigs?
> What justifies the extra price on the Martas?
Lighter, I believe, though ICBW.
> I'm not quibbling on price. I will pay _whatever_is_necessary_ to get
> the product that is best for _me_. I will be using this trike to get
> down the very steep hills on my commute to work. I have never been able
> to bike these descents and have trouble even walking them, such is the
> angle. There is about a km of dizzying descent, crossed with traffic
> intersections. I _must_ be confident that I can stop.
>
> But simplicity of maintenance is as important as powerful stopping. The
> other vocation of the trike will be to come touring with me in places
> where support may not be easily found, and to be on and off planes and
> trains. If hydraulic disks are too delicate, and by failing immobilize
> the entire vehicle, then they may not justify their extra cost.
If I were you I'd get hydraulics. They're easier to use (full
power with fingertip pressure, and your fingers are better at
sensitive operations than serious heaves) and the maintenance on
good ones is a non-issue except for a once in a while bleed (every
couple of years I guess, if that) and pad change (which mechanicals
will need too). Yes, they /can/ go wrong, but so can the frame, or
the wheels, or the rack etc. Mine haven't given me any trouble
touring, and if it was a real problem they wouldn't be as popular
as they are on touring machinery.
Finally, IIRC Mr. Larrington's appraisal of mechanical disc brakes:
"a half-arsed Work of Stan". I've used hydraulic and mechanical
rim and disc brakes, and much prefer hydraulics.
Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/
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Date: 28 Aug 2007 20:51:54
From: coyoteboy
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic
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Artemisia wrote:
> I've been assuming all along that the brakes I would get on my new HPV
> Scorpion would be the Magura Big Hydraulic disc. I made this assumption
> because in the _Greenspeed_ customisation guide, these are given as the
> best choice for heavy riders in terms of max stopping power and subtlety
> of control. Greenspeed, unlike HPV, doesn't offer either the Martas or
> the Avids.
>
> Now I've been reading up on the competition, and have become confused.
> The Avid mechanical brakes are what come as standard. I've done some
> googling on these and have found the most incredibly consistent series
> of rave reviews. The consensus out there seems to be - people who fork
> out extra for hydraulic discs are plain stupid or misguided, the Avids
> are so good as to be unbeatable on function at a much lower price and
> much easier maintenance.
>
> I also learn that hydraulic brakes have brake fluid which can leak, and
> that they are a lot fiddlier to maintain, and a lot more delicate and
> likely to fail. Is this true?
>
> And does anyone know the difference between the Martas and the Bigs?
> What justifies the extra price on the Martas?
>
> I'm not quibbling on price. I will pay _whatever_is_necessary_ to get
> the product that is best for _me_. I will be using this trike to get
> down the very steep hills on my commute to work. I have never been able
> to bike these descents and have trouble even walking them, such is the
> angle. There is about a km of dizzying descent, crossed with traffic
> intersections. I _must_ be confident that I can stop.
>
> But simplicity of maintenance is as important as powerful stopping. The
> other vocation of the trike will be to come touring with me in places
> where support may not be easily found, and to be on and off planes and
> trains. If hydraulic disks are too delicate, and by failing immobilize
> the entire vehicle, then they may not justify their extra cost.
>
> Thanks for your experiences. Cheers,
>
> EFR
> Ile de France
Anyone waffling about reliability problems on a hydro disc brake is
misguided - I've run them for nigh 10 years now and never had one fail
(3 bikes, both ends hydro) Hopes and maggies. Its very very rare to have
seals or hoses blow mid-use - normally its after a crash or such like.
In these instances a cable will snap as easily as a hose gets ripped
out. They never need bleeding (unless its an open system and you bugger
about with it upside down). I'm inclined to favour hydros because I find
the lever feel is lovely and they feel solid, and that matters to me,
instilling confidence - I know i can lamp on my front disc at 40mph and
easily feather the brake as it locks,unlocks,locks - like ABS. With the
cable discs I've tried, and that is only a few in lesser conditions, i
found it felt a little like i was stretching the cable - when the disc
locked i had to back off the lever further to release it (possibly due
to elastic deformation in the cable?) - it just feels more clunky which
is not inspiring. I also know people who have problems with them
jamming up with mud off-road, and the cables take more maintenance-
hydros are fit and forget until the pads wear out.
That said, if I was using it on road I'd be happy with a cable disc no
problem and wouldn't waste the cash - the key thing is to test the
brakes, even between two hydros the power and feel can vary massively.
But IMO the ultimate answer is maintenance - only once have I stripped
and rebuilt my hope 4-pots, and that was due to a sticky piston as it
had been left soaked in mud and salt water for 6 months - the strip and
rebuild was easy with the right tools. It posed a slight problem when i
forgot to properly tighten the hose and it undid on the trail but that
was me not checking things, not the brake. But other than that I've
never touched any of my discs after fitting them - ever.
Test them and feel for yourself, preferably people with one thats bedded
in - remember it takes a fair bit of distance to bed a disc in properly.
J
J
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Date: 28 Aug 2007 19:02:22
From: landotter
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On Aug 28, 1:14 pm, Artemisia <nos...@free.fr > wrote:
> I've been assuming all along that the brakes I would get on my new HPV
> Scorpion would be the Magura Big Hydraulic disc. I made this assumption
> because in the _Greenspeed_ customisation guide, these are given as the
> best choice for heavy riders in terms of max stopping power and subtlety
> of control. Greenspeed, unlike HPV, doesn't offer either the Martas or
> the Avids.
>
> Now I've been reading up on the competition, and have become confused.
> The Avid mechanical brakes are what come as standard. I've done some
> googling on these and have found the most incredibly consistent series
> of rave reviews. The consensus out there seems to be - people who fork
> out extra for hydraulic discs are plain stupid or misguided, the Avids
> are so good as to be unbeatable on function at a much lower price and
> much easier maintenance.
They work as well as a brake needs to work, are mechanically simple
and easy to adjust. IMHO, hydro brakes can have wonderful lever feel--
but are really mechanical overkill for most riders. The Avids are a
classic, one less thing to worry about.
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Date: 28 Aug 2007 19:22:38
From: Steve
Subject: Re: Which Brakes? Avid Mechanical Disc? Magura Big or Marta Hydraulic Disc?
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On Tue, 28 Aug 2007 19:02:22 -0000, landotter wrote:
> On Aug 28, 1:14 pm, Artemisia <nos...@free.fr> wrote:
>> [14 quoted lines suppressed]
>
> They work as well as a brake needs to work, are mechanically simple
> and easy to adjust. IMHO, hydro brakes can have wonderful lever feel--
> but are really mechanical overkill for most riders. The Avids are a
> classic, one less thing to worry about.
All very true. I use avid on my mtb, if I was doing a lot of downhill I
would consider hydraulic but I'm not, and the avids work just fine for xc
riding.
The main overall reason for me is that I can fix a broken cable nearly
anywhere, I don't want to be held up trying to buy a hydraulic lead, or
trying to fix a problem when I'm right in the middle of a cycling holiday.
The hassle would just not be worth the benefit.
Steve
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