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Main
Date: 24 May 2007 16:29:38
From: rosco
Subject: Chain Crossover and Gearing
|
I'm trying to design a gearing setup for myself on a new bike I'll be
building up this year. The existing bike that I ride most has downtube
shifters and a 7 speed freewhell so the new Campagnolo 10 speed rear ergo
type setups are very new to me. I know the gearing of my existing bike
(39-52 front and 13-24 rear 7 speed) and know how much more capability I'd
like having from those 3 extra gears in the back. I've been playing with
both Sheldon's gear calculator and the one at
http://www.jbarrm.com/cycal/cycal.html to help figure this out.
I really want to design the setup so I shift to the bigger front chainwheel
at a particular point in the gearing range. What I don't know is what
amount of chain crossover is generally considered good practice with a 10
speed rear setup. The answer to this question really lets me decide whether
a compact crank setup is the best thing for me, or if I should consider
going with a traditional triple up front.
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Date: 25 May 2007 14:37:16
From: russellseaton1@yahoo.com
Subject: Re: Chain Crossover and Gearing
|
On May 25, 4:10 pm, "Sandy" <leu...@frree.fr > wrote:
> Dans le message denews:1180126449.104099.52700@u30g2000hsc.googlegroups.c=
om,
> russellseat...@yahoo.com <russellseat...@yahoo.com> a r=E9fl=E9chi, et pu=
is a
> d=E9clar=E9 :
>
> > And of course a triple solves all problems since you get nice 53-42-30
> > rings and can use the nice 13-26 cassette with a straight block 13-19
> > then 21-23-26. And cheaply change the 30 ring to 28 or 26 or 24 for
> > $10 or less and get even lower gears. Lots of nice overlap so you are
> > not gong back and forth all the time on a compact.
>
> Each person can ask and answer his own Q. I moved from a 44 to a 42 when=
I
> hit a point, and to a 39 at another point. Both with 23 at the back. No=
w,
> 20 years after the first change, I have a 13-29 cassette that does not get
> used ; rather it's the 13-26. On a normally hilly ride, I touch the 21 a
> little, and for real climbs, I get to the 23 and 26 for a bit. I won't w=
ear
> them out soon. Those are bailout gears, too.
The original question asker has a 39x24 low gear now and wants lower
gears. With a 53-39 double and 13-26, 39x26 low is not much lower.
With a 13-29, 39x29 does get him quite a bit lower. Maybe not low
enough though.
>
> So, if I find myself in the last two cogs more often, I can go to a compa=
ct,
> which gives me 3 normally stepped gears further, and the big ring loses o=
ne.
> That's not yet, and won't be probably for another 3-5 years. You have to
> have a pretty big deficit in riding power to "need" a triple, which gives
> you bailout, not normal riding gears, beyond that.
In the mountains a triple is very useful. In many hilly parts of the
USA it is also useful. San Francisco Bay area for instance. Short-
medium extremely steep hills. Mr. Brandt and others grind up them.
Many don't want or can't grind and power up hills for a half mile,
mile or so. Triple is very useful. Many people just enjoy riding,
not racing or pretending to race. Recreation. They want to
comfortably climb the hills they run into. Slowly climb them. But
climb them without hurting their knees or over exerting themselves.
Triple is very useful.
>
> While a triple satisfies a mathematical model, the rider just needs to be
> honest with himself and choose based on his real riding. Having a potent=
ial
> of 4-6 more gears that don't see a chain seems a waste, when you can have
> useful ratios that are complicated with the triple setup.
How does a triple complicate ratios and make them not useful? I used
a 13-26 9 speed cassette with a double 53-42 and a triple 52-42-30
very well. If you don't want to use the inner ring, don't shift onto
it. Quite simple with Ergo. Just use the 53 and 42 rings with the
13-14-15-16-17-19-21-23-26 or add the 18 if 10 speed 13-26 cassette.
For me, the front
> two are kind of on/off positions that don't confuse me.
My triple crank has about the same chainrings as my double crank,
52-42 for the triple and 53-42 for the double. Nothign confusing
about that. On/off if you want to think of it that way. Triple just
adds a 30 or 28 or 26 or 24 inner ring too. I don't have to use it.
Remembering the
> exact transition points with a gear chart on the h-bar seems contrived, a=
nd
> landing in a bad ratio without this chart could well make riding less
> pleasant.
Compact doubles have the bad ratios from the transition point. Not
triples or doubles for the most part. 53-42 or 52-42-30 and a 13-23
or 13-26 cassette lets you run the 42 ring up to the mid 20s before
you need to go to the big ring. Or you can run the big ring down to
about 15mph before needing to go to the 42 ring. And the 42 ring lets
you go down to about 8mph before needing to go to the inner ring. No
bad ratios, no bad transitions, all very pleasant shifting with a
52-42-30 triple.
> --
> Sandy
> Verneuil-sur-Seine
> *******
>
> La vie, c'est comme une bicyclette,
> il faut avancer pour ne pas perdre l'=E9quilibre.
> -- Einstein, A.
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Date: 25 May 2007 13:54:09
From: russellseaton1@yahoo.com
Subject: Re: Chain Crossover and Gearing
|
On May 24, 10:20 pm, "rosco"
<reverse_the_charactrers_before_the_at_sign-ocso...@hotmail.com >
wrote:
> "Michael Press" <rub...@pacbell.net> wrote in message
>
> news:rubrum-21FE91.19043624052007@newsclstr02.news.prodigy.com...
>
>
>
>
>
> > In article <S3j5i.9210$ix.3428@trndny01>,
> > "rosco"
> > <reverse_the_charactrers_before_the_at_sign-ocso...@hotmail.com>
> > wrote:
>
> >> I'm trying to design a gearing setup for myself on a new bike I'll be
> >> building up this year. The existing bike that I ride most has downtube
> >> shifters and a 7 speed freewhell so the new Campagnolo 10 speed rear ergo
> >> type setups are very new to me. I know the gearing of my existing bike
> >> (39-52 front and 13-24 rear 7 speed) and know how much more capability
> >> I'd
> >> like having from those 3 extra gears in the back. I've been playing with
> >> both Sheldon's gear calculator and the one at
> >>http://www.jbarrm.com/cycal/cycal.htmlto help figure this out.
>
> >> I really want to design the setup so I shift to the bigger front
> >> chainwheel
> >> at a particular point in the gearing range. What I don't know is what
> >> amount of chain crossover is generally considered good practice with a 10
> >> speed rear setup. The answer to this question really lets me decide
> >> whether
> >> a compact crank setup is the best thing for me, or if I should consider
> >> going with a traditional triple up front.
>
> > All but the big-big and small-small are good.
> > Is your current range good now?
> > Or do you find yourself having to shift in front too often?
> > Why not just get a 39-52 with a 12-25 ( 12,13,14,15,16,17,19,21,23,25)
>
> > 87.8 117.0
> > 81.0 108.0
> > 75.2 100.3
> > 70.2 93.6
> > 65.8 87.8
> > 61.9 82.6
> > 55.4 73.9
> > 50.1 66.9
> > 45.8 61.0
> > 42.1 56.2
>
> > or 13-26 (13,14,15,16,17,18,19,21,23,26) cassette?
>
> > 81.0 108.0
> > 75.2 100.3
> > 70.2 93.6
> > 65.8 87.8
> > 61.9 82.6
> > 58.5 78.0
> > 55.4 73.9
> > 50.1 66.9
> > 45.8 61.0
> > 40.5 54.0
>
> > --
> > Michael Press
>
> Actually looking for some lower gears. My legs (and the rest of me) are 20
> years older than when I setup the current bike. The current gears are still
> fine except for the bigger hills. I'm far from a competitive cyclist, but
> usually get in 3K miles / year as long as the snow doesn't fly too early. I
> tend to stay in lower gears and pedal at higher rpm these days. Top-end
> speed doesn't matter to me so I can easily sacrifice some of the gears at
> the high-end. I just want to make sure the front chainwheel cross-over is
> high-enough so I'm not forever switching back and forth.
>
> The idea of a triple has crossed my mind (Campy with 30/40/50 front), and
> the gear chart shows that would work just fine with a 13-26 rear, but I also
> like the idea of getting much of that range (giving up a little on the low
> end) with a more simple compact front if I can get the cross over at the
> right place.- Hide quoted text -
>
> - Show quoted text -
Simple compact front? What is more simple about a compact double than
a triple? With Ergo, shifting between rings is so easy. Maybe once a
year you might overshift and go from the outer ring to the inner ring,
when you wanted to end up on the middle ring. If you think shifting a
double is so much simpler than shifting a triple with Ergo, then you
probably have never used Ergo. You are far more likely to overshift
downtube or bar end shifters than Ergo.
If you only need a little lower gears, then a standard double 53-39
with a 13-29 cassette would work very well for you. 39x24=43"=10.2mph
at 80rpm. 39x29=36"=8.5mph at 80rpm. A 50-34 compact with 13-29
would get a low of 34x29=31"=7.4mph at 80rpm. The 50x26(last good
usable gear on the compact big ring)=51"=12.1mph at 80rpm.
And of course a triple solves all problems since you get nice 53-42-30
rings and can use the nice 13-26 cassette with a straight block 13-19
then 21-23-26. And cheaply change the 30 ring to 28 or 26 or 24 for
$10 or less and get even lower gears. Lots of nice overlap so you are
not gong back and forth all the time on a compact.
I have a micro compact crank, 94mm bcd spider, 46-30 rings. 12-23 10
speed cassette. The good usable low gear of 46x21 is not really too
low. So many times I grind it out in the 46x21 or 46x23 up a hill to
avoid the huge drop to the inner ring and resulting double shifting
and loss of momentum and jump up in cadence. The highest gear on the
inner ring, 30x13 is not really high enough to be in unless you are in
the middle of a stair step climb. My crossover point with my compact
setup is not the worst I'm sure. But its still not a perfect place.
I will likely try to remedy this problem with a 12-23 cassette. The
extra 25 cog will lower the crossover point enough to maybe fix
things. And when you get into the bigger cogs with the outer ring, 46
for me, the 2 tooth jumps from 17-19-21-23-25 make lots more sense
than the 17-18-19 1 tooth jumps I have now.
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| | |
Date: 26 May 2007 02:18:32
From: rosco
Subject: Re: Chain Crossover and Gearing
|
> If you think shifting a
> double is so much simpler than shifting a triple with Ergo, then you
> probably have never used Ergo. You are far more likely to overshift
> downtube or bar end shifters than Ergo.
>
You are correct, I have never used Ergo other than checkout the shape and
feel of the brifters to know they suite me fine. I am coming from 7 speed
Dura-Ace around 1988 vintage with downtube shifters.
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| | |
Date: 25 May 2007 23:10:02
From: Sandy
Subject: Re: Chain Crossover and Gearing
|
Dans le message de
news:1180126449.104099.52700@u30g2000hsc.googlegroups.com,
russellseaton1@yahoo.com <russellseaton1@yahoo.com > a réfléchi, et puis a
déclaré :
> And of course a triple solves all problems since you get nice 53-42-30
> rings and can use the nice 13-26 cassette with a straight block 13-19
> then 21-23-26. And cheaply change the 30 ring to 28 or 26 or 24 for
> $10 or less and get even lower gears. Lots of nice overlap so you are
> not gong back and forth all the time on a compact.
Each person can ask and answer his own Q. I moved from a 44 to a 42 when I
hit a point, and to a 39 at another point. Both with 23 at the back. Now,
20 years after the first change, I have a 13-29 cassette that does not get
used ; rather it's the 13-26. On a normally hilly ride, I touch the 21 a
little, and for real climbs, I get to the 23 and 26 for a bit. I won't wear
them out soon. Those are bailout gears, too.
So, if I find myself in the last two cogs more often, I can go to a compact,
which gives me 3 normally stepped gears further, and the big ring loses one.
That's not yet, and won't be probably for another 3-5 years. You have to
have a pretty big deficit in riding power to "need" a triple, which gives
you bailout, not normal riding gears, beyond that.
While a triple satisfies a mathematical model, the rider just needs to be
honest with himself and choose based on his real riding. Having a potential
of 4-6 more gears that don't see a chain seems a waste, when you can have
useful ratios that are complicated with the triple setup. For me, the front
two are kind of on/off positions that don't confuse me. Remembering the
exact transition points with a gear chart on the h-bar seems contrived, and
landing in a bad ratio without this chart could well make riding less
pleasant.
--
Sandy
Verneuil-sur-Seine
*******
La vie, c'est comme une bicyclette,
il faut avancer pour ne pas perdre l'équilibre.
-- Einstein, A.
|
| |
Date: 25 May 2007 02:04:36
From: Michael Press
Subject: Re: Chain Crossover and Gearing
|
In article <S3j5i.9210$ix.3428@trndny01 >,
"rosco"
<reverse_the_charactrers_before_the_at_sign-ocsor_g@hotmail.com >
wrote:
> I'm trying to design a gearing setup for myself on a new bike I'll be
> building up this year. The existing bike that I ride most has downtube
> shifters and a 7 speed freewhell so the new Campagnolo 10 speed rear ergo
> type setups are very new to me. I know the gearing of my existing bike
> (39-52 front and 13-24 rear 7 speed) and know how much more capability I'd
> like having from those 3 extra gears in the back. I've been playing with
> both Sheldon's gear calculator and the one at
> http://www.jbarrm.com/cycal/cycal.html to help figure this out.
>
> I really want to design the setup so I shift to the bigger front chainwheel
> at a particular point in the gearing range. What I don't know is what
> amount of chain crossover is generally considered good practice with a 10
> speed rear setup. The answer to this question really lets me decide whether
> a compact crank setup is the best thing for me, or if I should consider
> going with a traditional triple up front.
All but the big-big and small-small are good.
Is your current range good now?
Or do you find yourself having to shift in front too often?
Why not just get a 39-52 with a 12-25 ( 12,13,14,15,16,17,19,21,23,25)
87.8 117.0
81.0 108.0
75.2 100.3
70.2 93.6
65.8 87.8
61.9 82.6
55.4 73.9
50.1 66.9
45.8 61.0
42.1 56.2
or 13-26 (13,14,15,16,17,18,19,21,23,26) cassette?
81.0 108.0
75.2 100.3
70.2 93.6
65.8 87.8
61.9 82.6
58.5 78.0
55.4 73.9
50.1 66.9
45.8 61.0
40.5 54.0
--
Michael Press
|
| | |
Date: 25 May 2007 03:20:21
From: rosco
Subject: Re: Chain Crossover and Gearing
|
"Michael Press" <rubrum@pacbell.net > wrote in message
news:rubrum-21FE91.19043624052007@newsclstr02.news.prodigy.com...
> In article <S3j5i.9210$ix.3428@trndny01>,
> "rosco"
> <reverse_the_charactrers_before_the_at_sign-ocsor_g@hotmail.com>
> wrote:
>
>> I'm trying to design a gearing setup for myself on a new bike I'll be
>> building up this year. The existing bike that I ride most has downtube
>> shifters and a 7 speed freewhell so the new Campagnolo 10 speed rear ergo
>> type setups are very new to me. I know the gearing of my existing bike
>> (39-52 front and 13-24 rear 7 speed) and know how much more capability
>> I'd
>> like having from those 3 extra gears in the back. I've been playing with
>> both Sheldon's gear calculator and the one at
>> http://www.jbarrm.com/cycal/cycal.html to help figure this out.
>>
>> I really want to design the setup so I shift to the bigger front
>> chainwheel
>> at a particular point in the gearing range. What I don't know is what
>> amount of chain crossover is generally considered good practice with a 10
>> speed rear setup. The answer to this question really lets me decide
>> whether
>> a compact crank setup is the best thing for me, or if I should consider
>> going with a traditional triple up front.
>
> All but the big-big and small-small are good.
> Is your current range good now?
> Or do you find yourself having to shift in front too often?
> Why not just get a 39-52 with a 12-25 ( 12,13,14,15,16,17,19,21,23,25)
>
> 87.8 117.0
> 81.0 108.0
> 75.2 100.3
> 70.2 93.6
> 65.8 87.8
> 61.9 82.6
> 55.4 73.9
> 50.1 66.9
> 45.8 61.0
> 42.1 56.2
>
> or 13-26 (13,14,15,16,17,18,19,21,23,26) cassette?
>
> 81.0 108.0
> 75.2 100.3
> 70.2 93.6
> 65.8 87.8
> 61.9 82.6
> 58.5 78.0
> 55.4 73.9
> 50.1 66.9
> 45.8 61.0
> 40.5 54.0
>
> --
> Michael Press
Actually looking for some lower gears. My legs (and the rest of me) are 20
years older than when I setup the current bike. The current gears are still
fine except for the bigger hills. I'm far from a competitive cyclist, but
usually get in 3K miles / year as long as the snow doesn't fly too early. I
tend to stay in lower gears and pedal at higher rpm these days. Top-end
speed doesn't matter to me so I can easily sacrifice some of the gears at
the high-end. I just want to make sure the front chainwheel cross-over is
high-enough so I'm not forever switching back and forth.
The idea of a triple has crossed my mind (Campy with 30/40/50 front), and
the gear chart shows that would work just fine with a 13-26 rear, but I also
like the idea of getting much of that range (giving up a little on the low
end) with a more simple compact front if I can get the cross over at the
right place.
|
| | | |
Date: 25 May 2007 18:39:47
From: Nigel Cliffe
Subject: Re: Chain Crossover and Gearing
|
rosco wrote:
>
> Actually looking for some lower gears. My legs (and the rest of me)
> are 20 years older than when I setup the current bike. The current
> gears are still fine except for the bigger hills. I'm far from a
> competitive cyclist, but usually get in 3K miles / year as long as
> the snow doesn't fly too early. I tend to stay in lower gears and
> pedal at higher rpm these days. Top-end speed doesn't matter to me
> so I can easily sacrifice some of the gears at the high-end. I just
> want to make sure the front chainwheel cross-over is high-enough so
> I'm not forever switching back and forth.
> The idea of a triple has crossed my mind (Campy with 30/40/50 front),
> and the gear chart shows that would work just fine with a 13-26 rear,
> but I also like the idea of getting much of that range (giving up a
> little on the low end) with a more simple compact front if I can get
> the cross over at the right place.
I think my riding is similar to how you've described things.
I've considered compact doubles, and decided that triple is easier to work.
My best bike has Campagnolo 10 speed, 30/40/50 front, 13-29 rear. I have
2005 shifters, I think the new 2007 QS shifters don't have the trimming
feature unless you go up to Chorus levers.
This combination doesn't cause me shifting problems, the ratios seem more
than close enough for my riding. I only use the small front on very steep
or if I am very tired, but am glad when its there.
On my heavier touring bike, which can be carrying holiday luggage, I have
lower ratios at the bottom of the range.
--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/
|
| | | |
Date: 25 May 2007 16:38:37
From: Booker C. Bense
Subject: Re: Chain Crossover and Gearing
|
-----BEGIN PGP SIGNED MESSAGE-----
In article <VBs5i.25085$xu.5220@trndny07 >,
rosco <reverse_the_charactrers_before_the_at_sign-ocsor_g@hotmail.com > wrote:
>
>Actually looking for some lower gears. My legs (and the rest of me) are 20
>years older than when I setup the current bike. The current gears are still
>fine except for the bigger hills. I'm far from a competitive cyclist, but
>usually get in 3K miles / year as long as the snow doesn't fly too early. I
>tend to stay in lower gears and pedal at higher rpm these days. Top-end
>speed doesn't matter to me so I can easily sacrifice some of the gears at
>the high-end. I just want to make sure the front chainwheel cross-over is
>high-enough so I'm not forever switching back and forth.
>
>The idea of a triple has crossed my mind (Campy with 30/40/50 front), and
>the gear chart shows that would work just fine with a 13-26 rear, but I also
>like the idea of getting much of that range (giving up a little on the low
>end) with a more simple compact front if I can get the cross over at the
>right place.
>
Trust me, I know exactly where you're at, get a triple if you
have a lot of hills to ride. IMHO, the standard gearing on
triples doesn't make a lot of sense with most 9-10 speed
cassettes (too much overlap), but that's easily fixed if you
replace the 30 with a 28 or 26.
I use
26-39-52 13-14-15-16-17-18-19-21-24
and I like that a lot.
_ Booker C. Bense
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|
| | | | |
Date: 25 May 2007 14:10:01
From: Michael Press
Subject: Re: Chain Crossover and Gearing
|
In article <f373ed$aib$1@news.Stanford.EDU >,
Booker C. Bense
<bbense+rec.bicycles.tech.May.25.07@telemark.slac.stan
ford.edu > wrote:
> Trust me, I know exactly where you're at, get a triple if you
> have a lot of hills to ride. IMHO, the standard gearing on
> triples doesn't make a lot of sense with most 9-10 speed
> cassettes (too much overlap), but that's easily fixed if you
> replace the 30 with a 28 or 26.
> I use
>
> 26-39-52 13-14-15-16-17-18-19-21-24
>
> and I like that a lot.
Ditto here.
--
Michael Press
|
| |
Date: 24 May 2007 20:46:38
From: Booker C. Bense
Subject: Re: Chain Crossover and Gearing
|
In article <S3j5i.9210$ix.3428@trndny01 >,
rosco <reverse_the_charactrers_before_the_at_sign-ocsor_g@hotmail.com > wrote:
>I'm trying to design a gearing setup for myself on a new bike I'll be
>building up this year. The existing bike that I ride most has downtube
>shifters and a 7 speed freewhell so the new Campagnolo 10 speed rear ergo
>type setups are very new to me. I know the gearing of my existing bike
>(39-52 front and 13-24 rear 7 speed) and know how much more capability I'd
>like having from those 3 extra gears in the back. I've been playing with
>both Sheldon's gear calculator and the one at
>http://www.jbarrm.com/cycal/cycal.html to help figure this out.
>
>I really want to design the setup so I shift to the bigger front chainwheel
>at a particular point in the gearing range. What I don't know is what
>amount of chain crossover is generally considered good practice with a 10
>speed rear setup.
_ I would think this would depend on the length of your
chainstays, the shorter the less the full gear set you can
use. I've never seen anyone state what angle is "bad" vs "good".
A safe guess would be 8 of 10.
> The answer to this question really lets me decide whether
>a compact crank setup is the best thing for me, or if I should consider
>going with a traditional triple up front.
_ I think the thing to think about is crossover point, compacts
almost always have a gap in gears when you go from big to
little. That's okay if that's not a speed you ride at much, but
I've used both and I found that if I couldn't do most/all of my
riding in just the big chainring and only use the small chainring
for long climbs, you end up doing a lot of up/down shifting and
"searching" around for the "right" gear.
_ Compacts are great if you just need one or two extra lower
gears and don't want to invest in new shifters. If you're starting
from scratch, I think you'll be happier in the long run just
by getting a triple. I've done hilly centuries with both
a compact and a triple and while the compact actually had an
overall lower "lowest" gear, I found having the triple
significantly more useful since there is more of a choice of gears
on those long climbs.
_ Booker C. Bense
|
|
