Should I shorten my chain?

[Eric Lambi]

Hello rec.bicycles.tech,

My SRAM chain has about 50 miles on it. I just installed a compact
crankset (largest chainring changed from 53 to 50), and made the
largest cog in the rear smaller to boot (23 to 21). Should I shorten
the chain? If so, how much?

Thanks,

Eric Lambi

 

[Andre]

The rule of thumb is to have the chain just long enough to cover the big
ring \ big cog combo, without locking up the rear derailleur. Excessively
long chains can allow for slack, which is no good either.

--
--------------------------
Andre Charlebois
AGC-PC support
http://agc-pc.tripod.com
BPE, MCSE4.0, CNA, A+

"Eric Lambi" <[email protected]> wrote in message
news:[email protected]...
> Hello rec.bicycles.tech,
>
> My SRAM chain has about 50 miles on it. I just installed a compact
> crankset (largest chainring changed from 53 to 50), and made the
> largest cog in the rear smaller to boot (23 to 21). Should I shorten
> the chain? If so, how much?
>
> Thanks,
>
> Eric Lambi

 

[Werehatrack]

On 27 Jul 2004 07:36:35 -0700, [email protected] (Eric Lambi)
wrote:

>Hello rec.bicycles.tech,
>
>My SRAM chain has about 50 miles on it. I just installed a compact
>crankset (largest chainring changed from 53 to 50), and made the
>largest cog in the rear smaller to boot (23 to 21). Should I shorten
>the chain? If so, how much?

There will probably be divergent advice on this. Mine is below.

Shift to the small/small combo; if it goes into that gear pair without
hanging, doesn't allow the chain to hit itself in the zigzag over the
jockey wheels, and doesn't produce chain droop, then there is no
*necessity* to shorten the chain. (There is a different criterion
which is more important; that the chain must be *long enough*, but
that is clearly not an issue in your case.) Weight weenies would, of
course, want to remove the excess grams. By one method of chain
fitting (which predicates that the chain should be no longer than
needed) you would remove the "excess" links. By another, as long as
the chain is within the limits of length which permit proper
derailleur function without chain droop, you're in good shape. One
consideration that may not be obvious; if you decide to swap things
around later for some reason, you may need to have that extra length.

Some additional opinions about chain fitment:

http://www.sheldonbrown.com/derailer-adjustment.html#chain

http://www.parktool.com/repair_help/FAQchainlength.shtml

http://draco.acs.uci.edu/rbfaq/FAQ/8d.3.html

These are by no means the only instructions out there.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Zog The Undeniable]

Eric Lambi wrote:

> Hello rec.bicycles.tech,
>
> My SRAM chain has about 50 miles on it. I just installed a compact
> crankset (largest chainring changed from 53 to 50), and made the
> largest cog in the rear smaller to boot (23 to 21). Should I shorten
> the chain? If so, how much?

Assuming it was correct to start with, take out one full link (1").
You've removed 2.5" from the big-big combination, but some of this would
be wrapped around the sprocket and you have to halve the distance anyway
because the chain is in a loop - so one link is just about right.

 

[Bill]

"Werehatrack" <[email protected]> wrote in message
news:[email protected]...
> On 27 Jul 2004 07:36:35 -0700, [email protected] (Eric Lambi)
> wrote:
>
> >Hello rec.bicycles.tech,
> >
> >My SRAM chain has about 50 miles on it. I just installed a compact
> >crankset (largest chainring changed from 53 to 50), and made the
> >largest cog in the rear smaller to boot (23 to 21). Should I shorten
> >the chain? If so, how much?
>
> There will probably be divergent advice on this. Mine is below.
>
> Shift to the small/small combo; if it goes into that gear pair without
> hanging, doesn't allow the chain to hit itself in the zigzag over the
> jockey wheels, and doesn't produce chain droop, then there is no
> *necessity* to shorten the chain. (There is a different criterion
> which is more important; that the chain must be *long enough*, but
> that is clearly not an issue in your case.) Weight weenies would, of
> course, want to remove the excess grams. By one method of chain
> fitting (which predicates that the chain should be no longer than
> needed) you would remove the "excess" links. By another, as long as
> the chain is within the limits of length which permit proper
> derailleur function without chain droop, you're in good shape.

I second the following:

> One consideration that may not be obvious; if you decide to swap things
> around later for some reason, you may need to have that extra length.
<snip>

If your chain works ok as is then leave the extra links for when you want to
stick your 23 back on or go to a 25 or 27 for a trip to the mountains. I
usually use a 23 but once or twice a year I stick on a 27 for extended
mountainous rides. My normal chain length accommodates the 27 and works with
no noticeable degradation with the 23.
Bill Brannon

 

[Jeff Wills]

"Bill" <[email protected]> wrote in message news:<[email protected]>...
<snip>
> I second the following:
>
> > One consideration that may not be obvious; if you decide to swap things
> > around later for some reason, you may need to have that extra length.
> <snip>
>
<snip>

I third Werehatrack's excellent advice. Given the current hazards of
unneccesarily breaking and replacing links (unless you build in
several links' worth of Powerlinks), I'd leave it as is.

Jeff

 

[Qui si parla Campagnolo]

eric-<< My SRAM chain has about 50 miles on it. I just installed a compact
crankset (largest chainring changed from 53 to 50), and made the
largest cog in the rear smaller to boot (23 to 21) >><BR><BR>
<< Should I shorten
the chain? If so, how much? >><BR><BR>

Yep, start with one link. Nice thing is you can check it since it has a snap
link.

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