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Main
Date: 10 Oct 2006 00:04:56
From:
Subject: Disk Brakes vs. V Brakes??
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Hi,
I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
for the first time, and would appreciate your input on my impressions:
- On the first bike I tried, it was not possible to block the wheel
with the disk brake. I checked and found that the disk was oily. On
another bike (same brake) I was able to get the wheel to block, but
with application of extreme force to the brake handle, MUCH more than
required by any V brake I ever tried.
Question: Are Hydraulic Brakes really weaker than V brakes, or was this
bike just assembled by monkeys?
- I noticed that the hydraulic disc brakes have a much 'spongier' feel
than the cable actuated V brakes. This I guess was related to the
hydraulic hose / brake line expanding under pressure, because it was ok
on the front brake (1/2 of the brake lever way until full braking), and
not acceptable no the rear brake (had to pull the brake lever almost up
to the handle bar to get full breaking power)
Question: Is this again a problem of monkey assembly (not enough
fluid?, air in the lines?, what else? ...), or cheap brake lines, or
both? And are there better brake lines that expand less than the stock
ones?
Or ARE hydraulic disc brakes just spongier? If yes, that much
spongier??
- After playing with the brakes for a few minutes, I noticed that the
discs get noticeably warm, around 170F. Are there ever heating issues
with disc brakes on longer downhill segments? Seems a stupid question,
but they did get quite warm just by playing around on level ground for
about ten minutes.
Thanks a lot!
PS: All the monkey references are founded on an employee there telling
me that 'there are no electrical brakes' when I asked for differences
between hydraulic and cable actuated. When I asked her that about the
front fork maxing out, i.e. hitting the limit of it's travel hard, she
replied with 'many people like their forks soft'. (I found out how they
can be adjusted later.) When I showed her that the (later found to be
well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
So monkeys or Neanderthals are definitely a possibility in that store.
But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
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Date: 17 Oct 2006 15:26:17
From: Alex
Subject: Re: Disk Brakes vs. V Brakes??
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Chris_MdR@gmx.net wrote:
> Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
> for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
> with the disk brake. I checked and found that the disk was oily. On
> another bike (same brake) I was able to get the wheel to block, but
> with application of extreme force to the brake handle, MUCH more than
> required by any V brake I ever tried.
>
> Question: Are Hydraulic Brakes really weaker than V brakes, or was this
> bike just assembled by monkeys?
My guess is that monkeys are to blame. I recently rode a couple of
bikes with hydraulic brakes. You should have a very solid feel to the
lever. You should be getting a lot of braking for a light touch on the
lever. I could get plenty fo braking power with just two fingers on
teh brake. I have relatively weak hands, so that says alot about the
braking power. I was very tempted to run with one finger on the brake.
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
> than the cable actuated V brakes.
This is a clear indication that something was wrong. Hydraulic brakes
should feel
very solid and hard. Spongy probably means air in the sytem.
>This I guess was related to the
> hydraulic hose / brake line expanding under pressure, because it was ok
> on the front brake (1/2 of the brake lever way until full braking), and
> not acceptable no the rear brake (had to pull the brake lever almost up
> to the handle bar to get full breaking power)
Air is the most likely culprit, not the hose.
> - After playing with the brakes for a few minutes, I noticed that the
> discs get noticeably warm, around 170F. Are there ever heating issues
> with disc brakes on longer downhill segments? Seems a stupid question,
> but they did get quite warm just by playing around on level ground for
> about ten minutes.
Brakes are supposed to get hot. That's how they work. They turn
kinetic energy into heat.
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
factor a new rotor and pads into the price discount.
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Please read the charter before posting: http://rbor.org/rbor_charter.txt
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Date: 15 Oct 2006 11:54:44
From: Johnny Sunset aka Tom Sherman
Subject: Re: Disk Brakes vs. V Brakes??
|
Chris_MdR@gmx.net wrote:
> ...
> PS: All the monkey references are founded on an employee there telling
> me that 'there are no electrical brakes' when I asked for differences
> between hydraulic and cable actuated....
If one has a bicycle with an electrical power assist hub, one could
create an electrical brake by having a switch to run the hub as a
dynamo with the current produced run through an air-cooled resistor
grid (such brakes are used on diesel-electric hybrid off-road dump
trucks and railroad locomotives).
V-Brake is a Shimano copyrighted name. For non-Shimano brakes (and for
generic reference to Shimano brakes), the correct term is "direct-pull
cantilever".
--
Tom Sherman - Here, not there.
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Date: 16 Oct 2006 20:53:06
From: Johnny Sunset aka Tom Sherman
Subject: Re: Disk Brakes vs. V Brakes??
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Chris Y.F.N.W. wrote:
> Group: rec.bicycles.misc Date: Sun, Oct 15, 2006, 11:54am (EDT-3) From:
> sunsetss0003@yahoo.com (Johnny Sunset aka Tom Sherman)
>
> >V-Brake is a Shimano copyrighted name.
> >For non-Shimano brakes (and for generic
> >reference to Shimano brakes), the
> >correct term is "direct-pull cantilever".
>
> Actually, the accepted popular generic term is, I believe
> "linear-pull"...]
Better tell Sheldon Brown:
<http://www.sheldonbrown.com/canti-direct.html >.
--
Tom Sherman - Here, not there.
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Date: 20 Oct 2006 12:44:27
From:
Subject: Re: Disk Brakes vs. V Brakes??
|
Bart Bailey wrote:
>
> Seems to me;
> Whether pulling or pushing, wire and fluid systems are both indirect,
> in that they both use an intermediary transfer method.
> A direct system would be to have the hand lever apply directly to the
> brake, like the old stagecoaches did.
Or maybe brake shoes clipped directly onto the thumb and forefinger?
;-)
- Frank Krygowski
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Date: 20 Oct 2006 21:18:40
From: Bart Bailey
Subject: Re: Disk Brakes vs. V Brakes??
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In Message-ID:<1161373467.819655.300010@i42g2000cwa.googlegroups.com >
posted on 20 Oct 2006 12:44:27 -0700, frkrygow@gmail.com wrote: Begin
>
>Bart Bailey wrote:
>>
>> Seems to me;
>> Whether pulling or pushing, wire and fluid systems are both indirect,
>> in that they both use an intermediary transfer method.
>> A direct system would be to have the hand lever apply directly to the
>> brake, like the old stagecoaches did.
>
>Or maybe brake shoes clipped directly onto the thumb and forefinger?
>;-)
>
>- Frank Krygowski
Yep, like the primitive neolite braking system,
with blue smoke curling up around your ankles.
--
Bart
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Date: 20 Oct 2006 09:42:00
From: Sheldon Brown
Subject: Re: Disk Brakes vs. V Brakes??
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Chris Y.F.N.W. wrote:
> >>Actually, the accepted popular generic term is, I believe "linear-pull"=
.=2E.
Tom Sherman replied:
> >Better tell Sheldon Brown:
Chris Y.F.N.W. wrote:
> Well, nothing against Sheldon, but he isn't the entire bicycle retail
> industry. In most of the catalogues / internet sites / magazines I've
> read, the term linear-pull is used more often than direct-pull.
Well, nothing against either of these folks but...
As a soi-disant cyclexicographer I am highly opinionated about certain
usages/misusages. Don't get me going about "brake arch" or "crank arm"
or "cogset."
However I have no major problem with either of these terms, and list
both in my Bicycle Glossary.
Actually, in casual conversation, I think most folks don't use either
of these terms, chosing instead to abuse Shimano's tradek "V-Brake."
In this spirit, I sometimes call them "v-type" brakes, because this is
generally understood colloquially.
> I prefer linear because all cable pull brakes are basically "direct". In
> that there ius a direct mechanical connection between the lever and the
> calipers with no intermediate mechanism, as in a hydraulic system.
Well, I have a mild preference for "direct" for two reasons:
=B7They are not actually "linear" though they are closer to linear than
traditional center-pull cantilevers.
=B7"Direct" refers to the fact that the cable from the lever acts
directly on the arms, rather than through the intermediary of a yoke
and transverse cable.
Strictly speaking I don't see that a cable connection is fundamentally
any more "direct" than a hydraulic system.
Sheldon "Can't We All Just Get Along?" Brown
+-----------------------------------------+
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Date: 22 Oct 2006 21:33:59
From: Chris Y.F.N.W.
Subject: Re: Disk Brakes vs. V Brakes??
|
Group: rec.bicycles.misc Date: Fri, Oct 20, 2006, 9:42am (EDT-3) From:
CaptBike@sheldonbrown.com (Sheldon=A0Brown)
>Strictly speaking I don't see that a cable
>connection is fundamentally any more
>"direct" than a hydraulic system.
My reason (and please don't take this as an arguement, i'm only
explaining myself) for calling cable pull systems "direct" as opposed to
hydraulic is that there the cable acts as a direct connection fron the
lever to the brake (or derailer)
Whereas, in a hydraulic system the lever actuates a piston which
compresses fluid which in turn actuates another piston which actuates
the brakes mechanism.
The same could be said for the electric derailer system that I forget
which manufacturer is currently messing around with. the instructions
are being sent to the mech. from the control by by indirect mean IOW, an
electrical current.
- -
Compliments of:
"Your 'picky-picky-picky' Wheelman"
If you want to E-mail me use:
ChrisZCorner "at" webtv "dot" net
My website:
http://geocities.com/czcorner
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Date: 20 Oct 2006 09:28:00
From: Chris Y.F.N.W.
Subject: Re: Disk Brakes vs. V Brakes??
|
Group: rec.bicycles.misc Date: Mon, Oct 16, 2006, 8:53pm (EDT-3) From:
sunsetss0003@yahoo.com (Johnny=A0Sunset=A0aka=A0Tom=A0Sherman)
>Chris Y.F.N.W. wrote:
>>Actually, the accepted popular generic >>term is, I believe
"linear-pull"...]
>Better tell Sheldon Brown:
>--
>Tom Sherman - Here, not there.
Well, nothing against Sheldon, but he isn't the entire bicycle retail
industry. In most of the catalogues / internet sites / magazines I've
read, the term linear-pull is used more often than direct-pull.
I prefer linear because all cable pull brakes are basically "direct". In
that there ius a direct mechanical connection between the lever and the
calipers with no intermediate mechanism, as in a hydraulic system.
- -
Compliments of:
"Your Friendly Neighborhood Wheelman"
If you want to E-mail me use:
ChrisZCorner "at" webtv "dot" net
My website:
http://geocities.com/czcorner
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Date: 20 Oct 2006 19:08:43
From: Bart Bailey
Subject: Re: Disk Brakes vs. V Brakes??
|
In Message-ID:<25768-4538CEE0-164@storefull-3235.bay.webtv.net > posted
on Fri, 20 Oct 2006 09:28:00 -0400, Chris Y.F.N.W. wrote: Begin
>I prefer linear because all cable pull brakes are basically "direct". In
>that there ius a direct mechanical connection between the lever and the
>calipers with no intermediate mechanism, as in a hydraulic system.
Seems to me;
Whether pulling or pushing, wire and fluid systems are both indirect,
in that they both use an intermediary transfer method.
A direct system would be to have the hand lever apply directly to the
brake, like the old stagecoaches did.
--
Bart
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Date: 16 Oct 2006 22:36:29
From: Chris Y.F.N.W.
Subject: Re: Disk Brakes vs. V Brakes??
|
Group: rec.bicycles.misc Date: Sun, Oct 15, 2006, 11:54am (EDT-3) From:
sunsetss0003@yahoo.com (Johnny=A0Sunset=A0aka=A0Tom=A0Sherman)
>V-Brake is a Shimano copyrighted name.
>For non-Shimano brakes (and for generic
>reference to Shimano brakes), the
>correct term is "direct-pull cantilever".
>--
>Tom Sherman - Here, not there.
Actually, the accepted popular generic term is, I believe
"linear-pull"...]
- -
Compliments of:
"Your Friendly Neighborhood Wheelman"
If you want to E-mail me use:
ChrisZCorner "at" webtv "dot" net
My website:
http://geocities.com/czcorner
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Date: 15 Oct 2006 19:30:02
From: bill
Subject: Re: Disk Brakes vs. V Brakes??
|
Johnny Sunset aka Tom Sherman wrote:
> Chris_MdR@gmx.net wrote:
>> ...
>> PS: All the monkey references are founded on an employee there telling
>> me that 'there are no electrical brakes' when I asked for differences
>> between hydraulic and cable actuated....
>
> If one has a bicycle with an electrical power assist hub, one could
> create an electrical brake by having a switch to run the hub as a
> dynamo with the current produced run through an air-cooled resistor
> grid (such brakes are used on diesel-electric hybrid off-road dump
> trucks and railroad locomotives).
Interesting take on it, but that only works down to a certain speed and
not to a full stop. Electrical generation requires movement of a wire
through a magnetic field and falls on it's face for a dead stop. You
still need contact brakes of some sort for that.
Bill Baka
>
> V-Brake is a Shimano copyrighted name. For non-Shimano brakes (and for
> generic reference to Shimano brakes), the correct term is "direct-pull
> cantilever".
>
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Date: 13 Oct 2006 14:08:29
From: Scott Gordo
Subject: Re: Disk Brakes vs. V Brakes??
|
Tosspot wrote:
> Werehatrack wrote:
> > On Thu, 12 Oct 2006 11:51:03 CST, Tosspot <FrankDotLeake@esa.int>
> > wrote:
> >
> >
> >>Werehatrack wrote:
> >>
> >>>On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
> >>>
> >>
> >><snip>
> >>
> >>>>- After playing with the brakes for a few minutes, I noticed that the
> >>>>discs get noticeably warm, around 170F.
> >>>
> >>>
> >>>Gosh, you had a contact thermometer available? I'm impressed.
> >>
> >>IR Thermometer. Every cyclist should have one.
> >>
> >>http://www.webbikeworld.com/r2/digital-infrared-thermometer/digital-infrared-thermometer.htm
> >
> >
> > I have one, actually, but it's a Raytek. I find that for small
> > surfaces, its utility is limited.
>
> <shrugs> I'm with the previous poster, great gadget, I just can't think
> what to use it for.
>
> Now the 83 piece tool kit I just bought, plus an angle grinder, is
> asking for one of these
>
> http://www.dutchbikes.nl/bodies_uk/frame_ks2.htm
>
>
>
> --
> rec.bicycles.off-road is moderated by volunteers. To find help solving
> posting problems, or contact the moderators, please see http://rbor.org/
> Please read the charter before posting: http://rbor.org/rbor_charter.txt
Wow!
http://www.dutchbikes.nl/bodies_uk/frame_kv4.htm
/s
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
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Date: 12 Oct 2006 10:20:29
From: Werehatrack
Subject: Re: Disk Brakes vs. V Brakes??
|
On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
>
>Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
>for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
>with the disk brake. I checked and found that the disk was oily.
Well, that would explain it. BTW, a brake which locks the front wheel
when the bike is actually being ridden can be an unpleasant thing to
have. If you get one, I suspect that you will discover this at some
point.
> On
>another bike (same brake) I was able to get the wheel to block, but
>with application of extreme force to the brake handle, MUCH more than
>required by any V brake I ever tried.
>
>Question: Are Hydraulic Brakes really weaker than V brakes, or was this
>bike just assembled by monkeys?
In my experience, most v-brakes require far less finger pressure to
produce a given amount of stopping power than a disc brake.
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
>than the cable actuated V brakes. This I guess was related to the
>hydraulic hose / brake line expanding under pressure, because it was ok
>on the front brake (1/2 of the brake lever way until full braking), and
>not acceptable no the rear brake (had to pull the brake lever almost up
>to the handle bar to get full breaking power)
Cable-operated disc brakes often have similar results. This is not
unusual for disc brakes as a class of unit, but results vary wildly
between setups; it is foolish to infer anything about a specific
brake's probable operating characteristics on the basis of other
brands or models. The only way to reliably establish what a given
brake does is to try it and see.
>Question: Is this again a problem of monkey assembly (not enough
>fluid?, air in the lines?, what else? ...), or cheap brake lines, or
>both? And are there better brake lines that expand less than the stock
>ones?
To each: Possibly.
>Or ARE hydraulic disc brakes just spongier? If yes, that much
>spongier??
Any brake can be made to work poorly. Some can't be made to work
well. Each must be evaluated on its own merits.
> - After playing with the brakes for a few minutes, I noticed that the
>discs get noticeably warm, around 170F.
Gosh, you had a contact thermometer available? I'm impressed.
>Are there ever heating issues
>with disc brakes on longer downhill segments? Seems a stupid question,
>but they did get quite warm just by playing around on level ground for
>about ten minutes.
Yes, it is possible to get disc brakes hot enough on a long descent
(especially with a heavy rider or on a steep grade) to discolor the
disc. Whether this is a problem depends on other factors that vary
from brake to brake.
>PS: All the monkey references are founded on an employee there telling
>me that 'there are no electrical brakes' when I asked for differences
>between hydraulic and cable actuated.
Correct: there are no electric brakes. If you used the term "cable
actuated" they should have known you were talking about something that
was not electrically operated, how did you manage to get them to think
that an electrical connection was involved?
>When I asked her that about the
>front fork maxing out, i.e. hitting the limit of it's travel hard, she
>replied with 'many people like their forks soft'. (I found out how they
>can be adjusted later.)
What does this have to do with brakes?
>When I showed her that the (later found to be
>well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
Oil contamination of disc brakes has been an issue with motorcycles as
well, for much longer. It happens. When the pads get oiled, you
generally have to replace them; if they're getting oiled by a leaking
fork, then you need a better fork. In the case of bicycles, the best
solution is often to go back to V-brakes, but not always.
>So monkeys or Neanderthals are definitely a possibility in that store.
>But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
I think I'd shop for something else.
--
Typoes are a feature, not a bug.
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Date: 12 Oct 2006 18:39:20
From: Bart Bailey
Subject: Re: Disk Brakes vs. V Brakes??
|
In Message-ID:<8mlni2lec8du7j4fj7t6koamloq2tcvf92@4ax.com > posted on
Thu, 12 Oct 2006 10:20:29 CST, Werehatrack wrote: Begin
>In my experience, most v-brakes require far less finger pressure to
>produce a given amount of stopping power than a disc brake.
My Nishiki Pueblo has the old Diacompe center pull rim brakes,
whereas the Giant AC has Hayes so1e hydraulic disk brakes,
and I don't notice that much difference at all,
in fact the cable brakes seem to have a bit of stretchiness
when hard applied versus the hydraulics, which feel solid.
I do have a fluke IR thermometer
but haven't done any field readings to see how hot either gets,
but suspect that it's the disks due to less total area of dissipation.
BTW: I'm an overweight (260 lb) pleasure class riding old geezer,
so my brakes get a fairly robust test when I cruise about town.
--
Bart
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Date: 13 Oct 2006 15:56:37
From: Werehatrack
Subject: Re: Disk Brakes vs. V Brakes??
|
On Thu, 12 Oct 2006 18:39:20 GMT, Bart Bailey <me2@privacy.net > wrote:
>In Message-ID:<8mlni2lec8du7j4fj7t6koamloq2tcvf92@4ax.com> posted on
>Thu, 12 Oct 2006 10:20:29 CST, Werehatrack wrote: Begin
>
>>In my experience, most v-brakes require far less finger pressure to
>>produce a given amount of stopping power than a disc brake.
>
>My Nishiki Pueblo has the old Diacompe center pull rim brakes,
I've got a set of those on an old C Itoh. The pull is high by
comparison to any of the V-brakes I have.
>whereas the Giant AC has Hayes so1e hydraulic disk brakes,
>and I don't notice that much difference at all,
>in fact the cable brakes seem to have a bit of stretchiness
>when hard applied versus the hydraulics, which feel solid.
That's they way I would have expected this comparison to run...but
then, as I said, I've got a set of those old Dia Compe brakes, so I
was expecting them to requires some effort.
>I do have a fluke IR thermometer
>but haven't done any field readings to see how hot either gets,
>but suspect that it's the disks
This would be my expectation as well.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
|
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Date: 12 Oct 2006 11:51:03
From: Tosspot
Subject: Re: Disk Brakes vs. V Brakes??
|
Werehatrack wrote:
> On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
>
<snip >
>>- After playing with the brakes for a few minutes, I noticed that the
>>discs get noticeably warm, around 170F.
>
>
> Gosh, you had a contact thermometer available? I'm impressed.
IR Thermometer. Every cyclist should have one.
http://www.webbikeworld.com/r2/digital-infrared-thermometer/digital-infrared-thermometer.htm
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
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| | | |
Date: 13 Oct 2006 10:54:30
From: Werehatrack
Subject: Re: Disk Brakes vs. V Brakes??
|
On Thu, 12 Oct 2006 11:51:03 CST, Tosspot <FrankDotLeake@esa.int >
wrote:
>Werehatrack wrote:
>> On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
>>
>
><snip>
>
>>>- After playing with the brakes for a few minutes, I noticed that the
>>>discs get noticeably warm, around 170F.
>>
>>
>> Gosh, you had a contact thermometer available? I'm impressed.
>
>IR Thermometer. Every cyclist should have one.
>
>http://www.webbikeworld.com/r2/digital-infrared-thermometer/digital-infrared-thermometer.htm
I have one, actually, but it's a Raytek. I find that for small
surfaces, its utility is limited.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see http://rbor.org/
Please read the charter before posting: http://rbor.org/rbor_charter.txt
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| | | | |
Date: 13 Oct 2006 11:25:07
From: Tosspot
Subject: Re: Disk Brakes vs. V Brakes??
|
Werehatrack wrote:
> On Thu, 12 Oct 2006 11:51:03 CST, Tosspot <FrankDotLeake@esa.int>
> wrote:
>
>
>>Werehatrack wrote:
>>
>>>On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
>>>
>>
>><snip>
>>
>>>>- After playing with the brakes for a few minutes, I noticed that the
>>>>discs get noticeably warm, around 170F.
>>>
>>>
>>>Gosh, you had a contact thermometer available? I'm impressed.
>>
>>IR Thermometer. Every cyclist should have one.
>>
>>http://www.webbikeworld.com/r2/digital-infrared-thermometer/digital-infrared-thermometer.htm
>
>
> I have one, actually, but it's a Raytek. I find that for small
> surfaces, its utility is limited.
<shrugs > I'm with the previous poster, great gadget, I just can't think
what to use it for.
Now the 83 piece tool kit I just bought, plus an angle grinder, is
asking for one of these
http://www.dutchbikes.nl/bodies_uk/frame_ks2.htm
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see http://rbor.org/
Please read the charter before posting: http://rbor.org/rbor_charter.txt
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| | | | | |
Date: 13 Oct 2006 18:51:30
From: Bart Bailey
Subject: Re: Disk Brakes vs. V Brakes??
|
In Message-ID:<egoei8$hdt$02$2@news.t-online.com > posted on Fri, 13 Oct
2006 11:25:07 CST, Tosspot wrote: Begin
>I'm with the previous poster, great gadget, I just can't think
>what to use it for.
I originally got mine in a moment of extravagance, thinking it would be
a fun instrument, and my initial suspicions weren't far off.
It's turned out to be one of the most interesting 'toys' I've bought in
a long while.
...and don't worry, if/when you get one, there'll be plenty of targets.
--
Bart
|
| | | |
Date: 13 Oct 2006 07:47:08
From: dgk
Subject: Re: Disk Brakes vs. V Brakes??
|
On Thu, 12 Oct 2006 11:51:03 CST, Tosspot <FrankDotLeake@esa.int >
wrote:
>Werehatrack wrote:
>> On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
>>
>
><snip>
>
>>>- After playing with the brakes for a few minutes, I noticed that the
>>>discs get noticeably warm, around 170F.
>>
>>
>> Gosh, you had a contact thermometer available? I'm impressed.
>
>IR Thermometer. Every cyclist should have one.
>
>http://www.webbikeworld.com/r2/digital-infrared-thermometer/digital-infrared-thermometer.htm
I'll admit that I'm dying to get one, but I really can't figure out
what I'd use it for. I guess it would be cool to have one when someone
asks if they have a temperature. Instead of the old tried and true
hand to the forehead, you can just zap them right between the eyes -
non-laser version probably better for this application.
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| | | |
Date: 12 Oct 2006 18:44:02
From: Bart Bailey
Subject: Re: Disk Brakes vs. V Brakes??
|
In Message-ID:<eglrne$6ke$02$1@news.t-online.com > posted on Thu, 12 Oct
2006 11:51:03 CST, Tosspot wrote: Begin
>Werehatrack wrote:
>> On Tue, 10 Oct 2006 00:04:56 CST, Chris_MdR@gmx.net wrote:
>>
>
><snip>
>
>>>- After playing with the brakes for a few minutes, I noticed that the
>>>discs get noticeably warm, around 170F.
>>
>>
>> Gosh, you had a contact thermometer available? I'm impressed.
>
>IR Thermometer. Every cyclist should have one.
>
>http://www.webbikeworld.com/r2/digital-infrared-thermometer/digital-infrared-thermometer.htm
Mine's the 62 http://tinyurl.com/vnq88
--
Bart
|
| |
Date: 12 Oct 2006 10:19:21
From: unas
Subject: Re: Disk Brakes vs. V Brakes??
|
Chris_MdR@gmx.net a écrit :
> Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
> for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
> with the disk brake. I checked and found that the disk was oily. On
> another bike (same brake) I was able to get the wheel to block, but
> with application of extreme force to the brake handle, MUCH more than
> required by any V brake I ever tried.
>
> Question: Are Hydraulic Brakes really weaker than V brakes, or was this
> bike just assembled by monkeys?
>
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
> than the cable actuated V brakes. This I guess was related to the
> hydraulic hose / brake line expanding under pressure, because it was ok
> on the front brake (1/2 of the brake lever way until full braking), and
> not acceptable no the rear brake (had to pull the brake lever almost up
> to the handle bar to get full breaking power)
>
> Question: Is this again a problem of monkey assembly (not enough
> fluid?, air in the lines?, what else? ...), or cheap brake lines, or
> both? And are there better brake lines that expand less than the stock
> ones?
> Or ARE hydraulic disc brakes just spongier? If yes, that much
> spongier??
>
> - After playing with the brakes for a few minutes, I noticed that the
> discs get noticeably warm, around 170F. Are there ever heating issues
> with disc brakes on longer downhill segments? Seems a stupid question,
> but they did get quite warm just by playing around on level ground for
> about ten minutes.
>
> Thanks a lot!
>
> PS: All the monkey references are founded on an employee there telling
> me that 'there are no electrical brakes' when I asked for differences
> between hydraulic and cable actuated. When I asked her that about the
> front fork maxing out, i.e. hitting the limit of it's travel hard, she
> replied with 'many people like their forks soft'. (I found out how they
> can be adjusted later.) When I showed her that the (later found to be
> well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
>
> --
> rec.bicycles.off-road is moderated by volunteers. To find help solving
> posting problems, or contact the moderators, please see http://rbor.org/
> Please read the charter before posting: http://rbor.org/rbor_charter.txt
the model that you use?
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|
| |
Date: 11 Oct 2006 00:58:40
From: jlee
Subject: Re: Disk Brakes vs. V Brakes??
|
> I'm not surprised. Tandems have double the weight and therefore double
> the energy to be dissipated while braking.
It will be more than double - significantly more as the double weight
going downhill only experiences the air resistance of a single rider.
As any rider knows from experience, the heavier rider will descent
faster (handling aside) than a lighter rider.
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Date: 11 Oct 2006 13:22:45
From: Matt O'Toole
Subject: Re: Disk Brakes vs. V Brakes??
|
On Wed, 11 Oct 2006 00:58:40 -0600, jlee wrote:
>> I'm not surprised. Tandems have double the weight and therefore double
>> the energy to be dissipated while braking.
> It will be more than double - significantly more as the double weight
> going downhill only experiences the air resistance of a single rider.
This is true.
Matt O.
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Date: 10 Oct 2006 20:51:08
From: Smokey
Subject: Re: Disk Brakes vs. V Brakes??
|
z wrote:
> treynolds@my-deja.com wrote:
> > jim beam wrote:
> > > Chris_MdR@gmx.net wrote:
> > > > Hi,
> > > >
> > > > - After playing with the brakes for a few minutes, I noticed that the
> > > > discs get noticeably warm, around 170F. Are there ever heating issues
> > > > with disc brakes on longer downhill segments? Seems a stupid question,
> > > > but they did get quite warm just by playing around on level ground for
> > > > about ten minutes.
> > >
> > > they get warm because of the friction - that's what all brakes do.
> > > you'll have no problem with heating issues on a disk braked bike - once
> > > set up correctly, use with complete confidence.
> > >
> >
> > Regarding the heating issue, I came across a couple on a tandem who had
> > a hydraulic disk brake in back, instead of a drag brake. They said
> > that on long downhills the brake heating transfers heat to the fluid,
> > the fluid expands and they end up with the brake applied without any
> > lever action. They have to stop and let the fluid cool.
> >
> > A tandem drag brake and a downhill ATB are not the exact same situation
> > but both can expect to sometimes apply the brake for 20-30 minutes on a
> > very long downhill. Does this ever occur on an ATB?
> >
>
> I've never had heat cause the brakes to apply through heat expansion.
> What I do experience is dot4 brake fluid boiling (or the water in the
> fluid boiling) and I loose all braking power. And I have to wait until
> it cools before continuing down hill. On the same hill with v-brakes I
> had a front tire blow because the rim got too hot.
>
> My make of disk brake is not compatible with dot5 fluid, which if I
> could use it, would help.
>
> Here's a question, which action produces the most heat, keeping the
> brakes on to control speed on a steep hill or letting the bike go and
> then jamming on the brakes at the last second to kill the speed?
> Laters,
>
> z
>
> --
>There is a higher temp grade of DOT fluid called DOT 5.1. Despite it's numerical designation, it IS NOT the same as DOT 5 fluid, it's a grade of DOT 4 developed specifically for high temp braking (wonder why they didn't call it 4.1?). Some of the motorcycle road racing teams are using it. Speaking of brake fluid, when I worked in a motorcycle shop, this was the second most neglected item of maintenance (changing the fluid). The most neglected was checking tire pressure.
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|
| |
Date: 10 Oct 2006 13:45:38
From: Marz
Subject: Re: Disk Brakes vs. V Brakes??
|
treynolds@my-deja.com wrote:
> jim beam wrote:
> > Chris_MdR@gmx.net wrote:
> > > Hi,
> > >
> > > - After playing with the brakes for a few minutes, I noticed that the
> > > discs get noticeably warm, around 170F. Are there ever heating issues
> > > with disc brakes on longer downhill segments? Seems a stupid question,
> > > but they did get quite warm just by playing around on level ground for
> > > about ten minutes.
> >
> > they get warm because of the friction - that's what all brakes do.
> > you'll have no problem with heating issues on a disk braked bike - once
> > set up correctly, use with complete confidence.
> >
>
> Regarding the heating issue, I came across a couple on a tandem who had
> a hydraulic disk brake in back, instead of a drag brake. They said
> that on long downhills the brake heating transfers heat to the fluid,
> the fluid expands and they end up with the brake applied without any
> lever action. They have to stop and let the fluid cool.
>
> A tandem drag brake and a downhill ATB are not the exact same situation
> but both can expect to sometimes apply the brake for 20-30 minutes on a
> very long downhill. Does this ever occur on an ATB?
>
I've never had heat cause the brakes to apply through heat expansion.
What I do experience is dot4 brake fluid boiling (or the water in the
fluid boiling) and I loose all braking power. And I have to wait until
it cools before continuing down hill. On the same hill with v-brakes I
had a front tire blow because the rim got too hot.
My make of disk brake is not compatible with dot5 fluid, which if I
could use it, would help.
Here's a question, which action produces the most heat, keeping the
brakes on to control speed on a steep hill or letting the bike go and
then jamming on the brakes at the last second to kill the speed?
Laters,
z
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| | |
Date: 10 Oct 2006 17:22:04
From: Michael Press
Subject: Re: Disk Brakes vs. V Brakes??
|
In article
<1160505867.555025.85930@i42g2000cwa.googlegroups.com >,
"z" <zjennings@gmail.com > wrote:
> Here's a question, which action produces the most heat, keeping the
> brakes on to control speed on a steep hill or letting the bike go and
> then jamming on the brakes at the last second to kill the speed?
> Laters,
Depends. If it is a fast road descent, you brake very
hard for a short time, then run up to speed again
whereupon the air flow cools the rim before much heat
gets to the tire. On a long slow descent, road or
trail, nothing works. You need to stop and let the
system cool.
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| | |
Date: 10 Oct 2006 14:21:19
From: Matt O'Toole
Subject: Re: Disk Brakes vs. V Brakes??
|
On Tue, 10 Oct 2006 13:45:38 -0600, z wrote:
> Here's a question, which action produces the most heat, keeping the
> brakes on to control speed on a steep hill or letting the bike go and
> then jamming on the brakes at the last second to kill the speed?
Believe it or not it's the latter. The amount of energy to be dissipated
is a product of the mass of bike and rider and the height of the hill,
which remains the same whether you go fast or slow. But at higher speeds
there's more airflow over the rims or brake disks, so more heat is
transferred to the air.
Matt O.
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| |
Date: 10 Oct 2006 13:33:31
From: Matt O'Toole
Subject: Re: Disk Brakes vs. V Brakes??
|
On Tue, 10 Oct 2006 00:04:56 -0600, Chris_MdR wrote:
If they're working properly, either brake should be able to lock the rear
wheel or send you over the handlebars. Disk brakes offer more precise
modulation and better performance in wet conditions, but their extra power
is really unnecessary because other kinds of brakes are more than powerful
enough. Most mountain bikes with decent forks and other equipment come
with disk brakes anyway, so that's what you'll get. Just make sure the
disks are clean and nothing is leaking, and you'll be fine. The same
applies to rim brakes, whether V-brakes, traditional cantilever, or caliper.
Matt O.
>
> Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
> for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
> with the disk brake. I checked and found that the disk was oily. On
> another bike (same brake) I was able to get the wheel to block, but
> with application of extreme force to the brake handle, MUCH more than
> required by any V brake I ever tried.
>
> Question: Are Hydraulic Brakes really weaker than V brakes, or was this
> bike just assembled by monkeys?
>
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
> than the cable actuated V brakes. This I guess was related to the
> hydraulic hose / brake line expanding under pressure, because it was ok
> on the front brake (1/2 of the brake lever way until full braking), and
> not acceptable no the rear brake (had to pull the brake lever almost up
> to the handle bar to get full breaking power)
>
> Question: Is this again a problem of monkey assembly (not enough
> fluid?, air in the lines?, what else? ...), or cheap brake lines, or
> both? And are there better brake lines that expand less than the stock
> ones?
> Or ARE hydraulic disc brakes just spongier? If yes, that much
> spongier??
>
> - After playing with the brakes for a few minutes, I noticed that the
> discs get noticeably warm, around 170F. Are there ever heating issues
> with disc brakes on longer downhill segments? Seems a stupid question,
> but they did get quite warm just by playing around on level ground for
> about ten minutes.
>
> Thanks a lot!
>
> PS: All the monkey references are founded on an employee there telling
> me that 'there are no electrical brakes' when I asked for differences
> between hydraulic and cable actuated. When I asked her that about the
> front fork maxing out, i.e. hitting the limit of it's travel hard, she
> replied with 'many people like their forks soft'. (I found out how they
> can be adjusted later.) When I showed her that the (later found to be
> well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
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|
| |
Date: 10 Oct 2006 12:46:37
From: treynolds@my-deja.com
Subject: Re: Disk Brakes vs. V Brakes??
|
jim beam wrote:
> Chris_MdR@gmx.net wrote:
> > Hi,
> >
> > - After playing with the brakes for a few minutes, I noticed that the
> > discs get noticeably warm, around 170F. Are there ever heating issues
> > with disc brakes on longer downhill segments? Seems a stupid question,
> > but they did get quite warm just by playing around on level ground for
> > about ten minutes.
>
> they get warm because of the friction - that's what all brakes do.
> you'll have no problem with heating issues on a disk braked bike - once
> set up correctly, use with complete confidence.
>
Regarding the heating issue, I came across a couple on a tandem who had
a hydraulic disk brake in back, instead of a drag brake. They said
that on long downhills the brake heating transfers heat to the fluid,
the fluid expands and they end up with the brake applied without any
lever action. They have to stop and let the fluid cool.
A tandem drag brake and a downhill ATB are not the exact same situation
but both can expect to sometimes apply the brake for 20-30 minutes on a
very long downhill. Does this ever occur on an ATB?
Tom
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|
| | |
Date: 10 Oct 2006 16:45:44
From: (PeteCresswell)
Subject: Re: Disk Brakes vs. V Brakes??
|
Per treynolds@my-deja.com:
>A tandem drag brake and a downhill ATB are not the exact same situation
>but both can expect to sometimes apply the brake for 20-30 minutes on a
>very long downhill. Does this ever occur on an ATB?
I've had my front brake (Hope C2) lock up in that manner when descending a very
steep hill.
Somebody who knows can chime in, but my suspicion is that phenom is limited to
closed-system hydraulic brakes.
I also think it's aggravated by having fluid that needs changing bc after I bled
the brake, it stopped happening.
--
PeteCresswell
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| | | |
Date: 10 Oct 2006 17:54:46
From: Bart Bailey
Subject: Re: Disk Brakes vs. V Brakes??
|
In Message-ID:<8b4oi2hpg4v758oddn9c8mfkb2rs9hujpi@4ax.com > posted on
Tue, 10 Oct 2006 16:45:44 CST, (PeteCresswell) wrote: Begin
>Per treynolds@my-deja.com:
>>A tandem drag brake and a downhill ATB are not the exact same situation
>>but both can expect to sometimes apply the brake for 20-30 minutes on a
>>very long downhill. Does this ever occur on an ATB?
>
>I've had my front brake (Hope C2) lock up in that manner when descending a very
>steep hill.
>
>Somebody who knows can chime in, but my suspicion is that phenom is limited to
>closed-system hydraulic brakes.
>
>I also think it's aggravated by having fluid that needs changing bc after I bled
>the brake, it stopped happening.
That might suggest bubbles
that expanded with prolonged application heating
causing the lockup
and would no longer be an issue after bleeding them out
You might think that those bubbles would tent to migrate upward toward
the hand lever and away from the source of heat however, unless there's
a slight leak at the connection to the hydraulic applicator and the
bubbles were forming there as you rode then subsequently heating before
their chance to float away.
--
Bart
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| | |
Date: 10 Oct 2006 13:34:20
From: Matt O'Toole
Subject: Re: Disk Brakes vs. V Brakes??
|
On Tue, 10 Oct 2006 12:46:37 -0600, treynolds@my-deja.com wrote:
> jim beam wrote:
>> Chris_MdR@gmx.net wrote:
>> > - After playing with the brakes for a few minutes, I noticed that
>> > the
>> > discs get noticeably warm, around 170F. Are there ever heating issues
>> > with disc brakes on longer downhill segments? Seems a stupid
>> > question, but they did get quite warm just by playing around on level
>> > ground for about ten minutes.
>> they get warm because of the friction - that's what all brakes do.
>> you'll have no problem with heating issues on a disk braked bike - once
>> set up correctly, use with complete confidence.
> Regarding the heating issue, I came across a couple on a tandem who had
> a hydraulic disk brake in back, instead of a drag brake. They said that
> on long downhills the brake heating transfers heat to the fluid, the
> fluid expands and they end up with the brake applied without any lever
> action. They have to stop and let the fluid cool.
I'm not surprised. Tandems have double the weight and therefore double
the energy to be dissipated while braking. If the brake components are
not upgraded to compensate it's likely they'll overheat. There are
tandem-specific disks for this reason. But because it's a smaller
ket they may not be as well-developed as single MTB brakes -- which
also had overheating problems in their early days.
> A tandem drag brake and a downhill ATB are not the exact same situation
> but both can expect to sometimes apply the brake for 20-30 minutes on a
> very long downhill. Does this ever occur on an ATB?
Yes. As I said, overheating was common with the first generation of
MTB disks.
The best "disk" is your rim, but overheating it can cause tires to blow
off, which is the reason for drag brakes at the hub on tandems.
Matt O.
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|
| |
Date: 10 Oct 2006 12:03:04
From: Dion Dock
Subject: Re: Disk Brakes vs. V Brakes??
|
> When I showed her that the (later found to be
> well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
I would strongly suggest you _run_ from a shop that is trying to sell a bike
with oiled braking surfaces. What else have they mis-assembled?
If you have to pay someone to get the bike to work, you're going to lose any
money you would save from their "sale" price. If you can do all the work
yourself, you don't need answers from rec.bicycles.tech.
-Dion
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| |
Date: 10 Oct 2006 11:03:32
From: jim beam
Subject: Re: Disk Brakes vs. V Brakes??
|
Chris_MdR@gmx.net wrote:
> Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
> for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
> with the disk brake. I checked and found that the disk was oily. On
> another bike (same brake) I was able to get the wheel to block, but
> with application of extreme force to the brake handle, MUCH more than
> required by any V brake I ever tried.
>
> Question: Are Hydraulic Brakes really weaker than V brakes, or was this
> bike just assembled by monkeys?
no, just assembled badly. hydraulic brakes are highly effective, more
so than rim brakes in off-road conditions.
>
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
> than the cable actuated V brakes. This I guess was related to the
> hydraulic hose / brake line expanding under pressure, because it was ok
> on the front brake (1/2 of the brake lever way until full braking), and
> not acceptable no the rear brake (had to pull the brake lever almost up
> to the handle bar to get full breaking power)
>
> Question: Is this again a problem of monkey assembly (not enough
> fluid?, air in the lines?, what else? ...), or cheap brake lines, or
> both? And are there better brake lines that expand less than the stock
> ones?
> Or ARE hydraulic disc brakes just spongier? If yes, that much
> spongier??
no, they're firm. sponginess means air in the line.
>
> - After playing with the brakes for a few minutes, I noticed that the
> discs get noticeably warm, around 170F. Are there ever heating issues
> with disc brakes on longer downhill segments? Seems a stupid question,
> but they did get quite warm just by playing around on level ground for
> about ten minutes.
they get warm because of the friction - that's what all brakes do.
you'll have no problem with heating issues on a disk braked bike - once
set up correctly, use with complete confidence.
>
> Thanks a lot!
>
> PS: All the monkey references are founded on an employee there telling
> me that 'there are no electrical brakes' when I asked for differences
> between hydraulic and cable actuated. When I asked her that about the
> front fork maxing out, i.e. hitting the limit of it's travel hard, she
> replied with 'many people like their forks soft'. (I found out how they
> can be adjusted later.) When I showed her that the (later found to be
> well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
>
> --
> rec.bicycles.off-road is moderated by volunteers. To find help solving
> posting problems, or contact the moderators, please see http://rbor.org/
> Please read the charter before posting: http://rbor.org/rbor_charter.txt
>
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| |
Date: 10 Oct 2006 10:33:59
From: Qui si parla Campagnolo
Subject: Re: Disk Brakes vs. V Brakes??
|
Chris_MdR@gmx.net wrote:
> Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
> for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
> with the disk brake. I checked and found that the disk was oily. On
> another bike (same brake) I was able to get the wheel to block, but
> with application of extreme force to the brake handle, MUCH more than
> required by any V brake I ever tried.
>
> Question: Are Hydraulic Brakes really weaker than V brakes, or was this
> bike just assembled by monkeys?
Number 2..rotors and pads must be free of any contamination.
>
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
> than the cable actuated V brakes. This I guess was related to the
> hydraulic hose / brake line expanding under pressure, because it was ok
> on the front brake (1/2 of the brake lever way until full braking), and
> not acceptable no the rear brake (had to pull the brake lever almost up
> to the handle bar to get full breaking power)
>
> Question: Is this again a problem of monkey assembly (not enough
> fluid?, air in the lines?, what else? ...), or cheap brake lines, or
> both? And are there better brake lines that expand less than the stock
> ones?
> Or ARE hydraulic disc brakes just spongier? If yes, that much
> spongier??
Brakes need to be bled. Lines don't flex or expand, poor setup.
>
> - After playing with the brakes for a few minutes, I noticed that the
> discs get noticeably warm, around 170F. Are there ever heating issues
> with disc brakes on longer downhill segments? Seems a stupid question,
> but they did get quite warm just by playing around on level ground for
> about ten minutes.
Temp no big deal. >
> Thanks a lot!
>
> PS: All the monkey references are founded on an employee there telling
> me that 'there are no electrical brakes' when I asked for differences
> between hydraulic and cable actuated. When I asked her that about the
> front fork maxing out, i.e. hitting the limit of it's travel hard, she
> replied with 'many people like their forks soft'. (I found out how they
> can be adjusted later.) When I showed her that the (later found to be
> well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
Typical of bike shop, USA..peopled by the untrained. Think that if they
ride a bike, they know something about them(no electric brakes, that is
amazing that she would say such a thing. I guess she has not heard of
'mechanical' disc brakes)
>
> --
> rec.bicycles.off-road is moderated by volunteers. To find help solving
> posting problems, or contact the moderators, please see http://rbor.org/
> Please read the charter before posting: http://rbor.org/rbor_charter.txt
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see http://rbor.org/
Please read the charter before posting: http://rbor.org/rbor_charter.txt
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Date: 10 Oct 2006 10:33:03
From: Smokey
Subject: Re: Disk Brakes vs. V Brakes??
|
Chris_MdR@gmx.net wrote:
> Hi,
>
> I tried a bike with hydraulic disk brakes (Hayes Sole V6) yesterday
> for the first time, and would appreciate your input on my impressions:
>
> - On the first bike I tried, it was not possible to block the wheel
> with the disk brake. I checked and found that the disk was oily. On
> another bike (same brake) I was able to get the wheel to block, but
> with application of extreme force to the brake handle, MUCH more than
> required by any V brake I ever tried.
>
> Question: Are Hydraulic Brakes really weaker than V brakes, or was this
> bike just assembled by monkeys?
>
> - I noticed that the hydraulic disc brakes have a much 'spongier' feel
> than the cable actuated V brakes. This I guess was related to the
> hydraulic hose / brake line expanding under pressure, because it was ok
> on the front brake (1/2 of the brake lever way until full braking), and
> not acceptable no the rear brake (had to pull the brake lever almost up
> to the handle bar to get full breaking power)
>
> Question: Is this again a problem of monkey assembly (not enough
> fluid?, air in the lines?, what else? ...), or cheap brake lines, or
> both? And are there better brake lines that expand less than the stock
> ones?
> Or ARE hydraulic disc brakes just spongier? If yes, that much
> spongier??
>
> - After playing with the brakes for a few minutes, I noticed that the
> discs get noticeably warm, around 170F. Are there ever heating issues
> with disc brakes on longer downhill segments? Seems a stupid question,
> but they did get quite warm just by playing around on level ground for
> about ten minutes.
>
> Thanks a lot!
>
> PS: All the monkey references are founded on an employee there telling
> me that 'there are no electrical brakes' when I asked for differences
> between hydraulic and cable actuated. When I asked her that about the
> front fork maxing out, i.e. hitting the limit of it's travel hard, she
> replied with 'many people like their forks soft'. (I found out how they
> can be adjusted later.) When I showed her that the (later found to be
> well oiled) disk didn't stop the bike, she said 'Oh. Eh? Uh?'
> So monkeys or Neanderthals are definitely a possibility in that store.
> But the bike is on sale, so I might still buy there. Uh. Uh. Uh. I
>
> --
I haven't worked on any hydraulic bicycle disc brakes, but have
worked on many motorcycle ones and that sure sounds like there is some
air in the lines that needs to be bled out.
Smokey
--
rec.bicycles.off-road is moderated by volunteers. To find help solving
posting problems, or contact the moderators, please see http://rbor.org/
Please read the charter before posting: http://rbor.org/rbor_charter.txt
|
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Date: 10 Oct 2006 09:54:38
From: Chris Y.F.N.W.
Subject: Re: Disk Brakes vs. V Brakes??
|
Group: rec.bicycles.misc Date: Tue, Oct 10, 2006, 12:04am (EDT-2) From:
Chris_MdR@gmx.net
>Hi,
>=A0=A0=A0=A0=A0=A0I tried a bike with hydraulic disk
>brakes (Hayes Sole V6) yesterday for the
>first time, and would appreciate your
>input on my impressions:
>=A0=A0- On the first bike I tried, it was not
>possible to block the wheel with the disk
>brake. I checked and found that the disk
>was oily. On another bike (same brake) I >was able to get the wheel to
block, but
>with application of extreme force to the
>brake handle, MUCH more than required
>by any V brake I ever tried.
>Question: Are Hydraulic Brakes really >weaker than V brakes, or was
this
>bike just assembled by monkeys?
Disk brakes are definitely not weaker than V's, especially better
hydraulic brakes (I am not counting the $#!^ usualy found on dime-store
bikes). Many things can cause bad brake performance, many of which you
guessed. Without actually examining the brakes, though, I cannot tell
you which.
Disk brakes are vulnerable to contaminates, especially oily ones, just
like rim brakes (any type). if there was oil on the disks, you might
have them checked for leaks. Oil on the disk is bad, Oil leaking from
the lines is bad.
>=A0=A0- I noticed that the hydraulic disc >brakes have a much
'spongier' feel than
>the cable actuated V brakes. This I
>guess was related to the hydraulic hose /
>brake line expanding under pressure,
>because it was ok on the front brake (1/2
>of the brake lever way until full braking),
>and not acceptable no the rear brake
>(had to pull the brake lever almost up to
>the handle bar to get full breaking power)
>Question: Is this again a problem of
>monkey assembly (not enough
>fluid?, air in the lines?, what else? ...), or
>cheap brake lines, or both? And are
>there better brake lines that expand less
>than the stock ones?
>Or ARE hydraulic disc brakes just
>spongier? If yes, that much spongier??
I have Hayes mechanical disks on my MTB and V's on my road tourer, and
there is a difference in "stiffness" regarding the lever feel there too.
Both stop great so I put the "sponginess" feeling down to increased
mechanical advantage in the disk, and yes, the rear is spongier than the
front due to extra cable length. Although the things you mentioned will
also create this feeling. the real factor to go by is performance. Does
the bike stop without too much [lever] effort?
>=A0=A0- After playing with the brakes for a few
>minutes, I noticed that the discs get
>noticeably warm, around 170F. Are there
>ever heating issues with disc brakes on
>longer downhill segments? Seems a
>stupid question, but they did get quite
>warm just by playing around on level
>ground for about ten minutes.
>
>Thanks a lot!
Disk brakes will get hot. that is a given. all brakes work by the same
principle; turning kinetic energy (motion) into heat. Hayes even warns
users not to touch the disks, especially after long periods of braking,
because they can get hot enough to cause burns. This is normal. disk
brakes get a lot hotter that rim brakes because they are a lot smaller,
there is not as much metal to absorb the heat. The pads are made
specially to work under these conditions,
Rim brakes, on the other hand, use rubber pads that do not work as well
when hot. But as noted before, a rim has a lot more mass to absorb all
that heat. the main worries with rim brake heating is too much heat
expanding the air in the tires leading to blow-off.
This ability to continue working (and not blow the tires) even when very
hot is one of the main reasons disk brakes are popular on tandems.
- -
Compliments of:
"Your Friendly Neighborhood Wheelman"
If you want to E-mail me use:
ChrisZCorner "at" webtv "dot" net
My website:
http://geocities.com/czcorner
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