Compact cranks and derailleur question

[Sheldon Brown]

Doug Taylor wrote:

> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
> The specs for both Ultegra and Dura Ace front derailleurs show a
> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
>
> So, will the Shimano derailleurs make the extra tooth jump? If so,
> will shifting up be sluggish? If so, why not sell the compact with
> 50-36? Or 35?

It will work fine. See: http://sheldonbrown.com/capacity

Sheldon "Eff Ay Cue" Brown
+---------------------------------------------------------+
| We are satisfied that there can be but little liberty |
| on earth while men worship a tyrant in heaven. |
| -- Robert Green Ingersoll |
+---------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[Doug Taylor]

The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
The specs for both Ultegra and Dura Ace front derailleurs show a
capacity to shift 15. The standard 130mm bcd 53-39 span is 14.

So, will the Shimano derailleurs make the extra tooth jump? If so,
will shifting up be sluggish? If so, why not sell the compact with
50-36? Or 35?

--dt

 

[Doug Taylor]

Sheldon Brown <[email protected]> wrote:

>Doug Taylor wrote:
>
>> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
>> The specs for both Ultegra and Dura Ace front derailleurs show a
>> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
>>
>> So, will the Shimano derailleurs make the extra tooth jump? If so,
>> will shifting up be sluggish? If so, why not sell the compact with
>> 50-36? Or 35?
>
>It will work fine. See: http://sheldonbrown.com/capacity

Thanks, Sheldon. I actually searched through your glossary prior to
my post, but didn't think to look under "capacity." Doh!

--dt

 

[psycholist]

"Doug Taylor" <[email protected]> wrote in message
news:[email protected]...
> Sheldon Brown <[email protected]> wrote:
>
> >Doug Taylor wrote:
> >
> >> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
> >> The specs for both Ultegra and Dura Ace front derailleurs show a
> >> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
> >>
> >> So, will the Shimano derailleurs make the extra tooth jump? If so,
> >> will shifting up be sluggish? If so, why not sell the compact with
> >> 50-36? Or 35?
> >
> >It will work fine. See: http://sheldonbrown.com/capacity
>
> Thanks, Sheldon. I actually searched through your glossary prior to
> my post, but didn't think to look under "capacity." Doh!
>
> --dt

It's working fine for me. I'm riding DA with FSA compact. Setup on my Trek
5500 isn't ideal. In fact, I didn't think it was going to work. But it
works just fine. I've never dropped a chain or noted any sluggishness in
the shifting whatsoever. And the stiffness of the crank is quite
noticeable. I really like it.

Bob C.

 

[David L. Johnson]

On Tue, 03 Aug 2004 11:56:52 -0400, Doug Taylor wrote:

> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
> The specs for both Ultegra and Dura Ace front derailleurs show a
> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
>
> So, will the Shimano derailleurs make the extra tooth jump?

No problem, though adjustment might need to be more precise.

> If so,
> will shifting up be sluggish?

No

> If so, why not sell the compact with
> 50-36? Or 35?

People going for this are looking for lower gears.

BTW, I use a 46/30, also 16 teeth, with a Campy front derailleur. No
problems at all. I did get a chain watcher, since when I put on the
granny (22 teeth), it did miss a few downshifts. I leave granny at home
unless I'm touring, but leave the chain watcher on. Probably a good idea
with a wide range front double.

--

David L. Johnson

__o | When you are up to your ass in alligators, it's hard to remember
_`\(,_ | that your initial objective was to drain the swamp. -- LBJ
(_)/ (_) |

 

[Qui si parla Campagnolo]

taylor-<< The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
The specs for both Ultegra and Dura Ace front derailleurs show a
capacity to shift 15. The standard 130mm bcd 53-39 span is 14. >><BR><BR>

The shimano or Campagnolo front ders for double will work fine with the
compact. We have done it many times.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

 

[Bill Davidson]

Doug Taylor wrote:
> So, will the Shimano derailleurs make the extra tooth jump? If so,
> will shifting up be sluggish? If so, why not sell the compact with
> 50-36? Or 35?

Others have answered that it will work fine (and they are correct).
I'm currently using an old Shimano 600 double front deraileur with
a triple crank and a 20T difference between big and small. I'm sure
it wasn't meant for that much. It's been no problem.

As to why they don't offer more sizes, I assume that's a sales
decision based upon what they think most customers will want and
how much it will cost them to supply more sizes.

It's easy enough to buy a bigger chain ring if you want one. 110's
are not too difficult to find in many sizes.

Another problem might be rear deraileur capacity. You might want
to look into a medium or long cage rear deraileur to handle your
larger range of gearing. A normal road deraileur meant for a normal
double may be fine if you have a minimal range rear cluster but if
you've got a lot of range in the back too, you're going to need to
take up more chain slack or not have enough chain to use the larger
few cogs in the back with the large ring in the front. For example,
if you have an 11-27 in the back, that's 16T + 16T on the front
for 32T. The Ultegra rear deraileur for double is rated for 29T
total capacity and the triple is rated for 37T total capacity. 32T
may be close enough; especially since big-big is probably not a good
gear to be in but if you go much wider, it could be a problem
without the long cage rear deraileur.

BTW, I'm using a regular short rear deraileur with my 13-26 in the
back and it *is* a problem. I've got way too much slack on the
small-small combination so I don't go near it. There isn't enough
chain for big-big so I can't do that either. I probably wouldn't
use those extremes anyway but I really don't even have the choice.

 

[Eagle Jackson]

Doug Taylor <[email protected]> wrote in message news:<[email protected]>...
> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
> The specs for both Ultegra and Dura Ace front derailleurs show a
> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
>
> So, will the Shimano derailleurs make the extra tooth jump? If so,
> will shifting up be sluggish? If so, why not sell the compact with
> 50-36? Or 35?
>
> --dt

I changed to FSA compact cranks on my DA equipped Merlin and it works
just fine. No shifting problems at all. I got the cranks for my trip
to the French Alps this summer and I was very happy to have the
compact cranks. They made up for my lack of training and advancing
age. Oh, they look cool too and are very stiff and light. I like the
cranks so much that now that I'm back, I have not switched back to the
DA cranks.

I find that I shift between the big ring and little ring more with the
50-34 than I did with the 53-39, so it's a good thing that front
shifting is just fine.

 

[Paul Kopit]

I've found that if the big ring has good shift assists, that either
Campy or Shimano front derailleurs work fine. I regularly use SR
chainring and also Shimano HG. The shift assists are zero to minimal.
The Campy front derailleur is a clear winner.

I have not had to use longer cage rear derailleurs on my bikes or my
wife's. With 50/34 and a standard cage rear derailleur, I can shift
13/29 and cross chain either way. A bicycle with longer chainstays
would do better with medium cage derailleur. I needed to use a long
cage rear derailleur on a single touring bicycle that had 50/36 x
12/32. I needed 2 full links longer than I use on my Cannondale CAADx
bikes.

 

[Doug Taylor]

[email protected] (Eagle Jackson) wrote:

>I changed to FSA compact cranks on my DA equipped Merlin and it works
>just fine. No shifting problems at all. I got the cranks for my trip
>to the French Alps this summer and I was very happy to have the
>compact cranks. They made up for my lack of training and advancing
>age. Oh, they look cool too and are very stiff and light. I like the
>cranks so much that now that I'm back, I have not switched back to the
>DA cranks.
>
>I find that I shift between the big ring and little ring more with the
>50-34 than I did with the 53-39, so it's a good thing that front
>shifting is just fine.

What cassette do you use?
--dt

 

[Eagle Jackson]

Doug Taylor <[email protected]> wrote in message is just fine.
>
> What cassette do you use?
> --dt

I use both a 12-25 and a 13-27. I put the 13-27 on while in Europe
for the ride up Alpe d'Huez. I also have a 12-23 that I will also use
but haven't yet tried with the compact crank.

The bike is a 55cm Merlin Extralight with 9sp DA.

My wife has a Spectrum with Campy Record 10s. She put an FSA compact
crank on her bike too for the trip and loves it. She rides a 13-26
and 13-29. Actually, first she put a triple on and didn't like it at
all. She saw how much I liked my compact crank so she switched to one
too, and loved it.

 

[Doug Taylor]

[email protected] (Eagle Jackson) wrote:

>> What cassette do you use?
>> --dt
>
>I use both a 12-25 and a 13-27. I put the 13-27 on while in Europe
>for the ride up Alpe d'Huez. I also have a 12-23 that I will also use
>but haven't yet tried with the compact crank.

Thanks. I ask because of other posts questioning whether a normal
cage derailleur and the chain will handle the gearing with compact
front rings and big teeth cassettes.

Once I get my cranks, I'm thinking of switching the 34 tooth small
ring with a 36, taking a link out of the chain I'm running with the
53-39, and staying with my 12-26 cassette. If that's not low enough
for big grades, I'll see how the 34 works.

Checking out gear ratio charts, I notice that running a 11-23 cassette
puts me close to where I was with the standard front rings and the
12-26 cassette for riding tamer terrain.

--dt

 

[Paul Kopit]

On Fri, 06 Aug 2004 16:17:21 -0400, Doug Taylor
<[email protected]> wrote:

>Once I get my cranks, I'm thinking of switching the 34 tooth small
>ring with a 36, taking a link out of the chain I'm running with the
>53-39, and staying with my 12-26 cassette. If that's not low enough
>for big grades, I'll see how the 34 works.

Actually, you'd be better off with 48/34 with the 12/26. Keep the
50/34.