SRAM RD Cage Lengths

[minjin]

Can any hubbers tell me what the difference is (besides the obvious length difference). I cannot see specs on the SRAM website and unless I am really blind cannot see any markings on mine. It is an X-9. Would it make a difference if I used a different length to what is currently on the bike.

thanks

[Pappa Bear]

Yes it does matter. Rule of thumb: use a long cage with 3 rings, medium cage with 2 rings and a shortcage with 1 ring

 

A short cage will not work on a bike with 3 front rings, the derailer can not take up all the slack in the chain (from the biggest to smallest ring)

[AndreZA]

What Google brought up.

 

 

Derailleurs have a rated capacity. This is their ability to take up excess chain. After all, you need just about all of your chain to run in the big-big combo, whereas you have a bunch of extra links doing nothing when you run in your small-small combo.

 

Not that either of those cross-chain combos are normal to run in, but let me get to that in a minute.

 

Manufacturer stated derailleur capacities are as follows:

Shimano long = 45T; medium = 33T

SRAM long = 43T; medium = 37T; short = 30T

 

The easy capacity formula is to add your big ring & cog sizes, then subtract your small ring and cog sizes. It looks like this:

 

cap req'd (T) = (BIG ring - small ring) + (BIG cog - small cog)

 

...so for a typical 44-32-22 mountain crank & 11-34 cassette...

 

T = (44T - 22T) + (34T - 11T)

.. = (22T) + (23T)

.. = 45T

[kosmonooit]

Also rear cassette ratio as mampara metions: I am using a medium cage on an 11-32 no problem on my road warrior training mtb, long cage on my on 'race' bike which has 11-34, both same 3x front rings, no problems. Both sram X0, worth the extra, they are better made.

[Mojoman]

Is this then the reasoning for using a 2 chainring crank, so you can use a shorter derailer at the rear?

[minjin]

Thanks guys - makes sense.

 

Is there also that much of a difference between x-9 and x-0?

[Goodbadugly]

When the x9 works, it works. BUT I have had 2 x9 rear derailleurs that got stuck in 'first' (32 or 34) gear during muddy races. I cleaned them (even tried oiling the links) but to no avail. The reason for this? Something to do with the plastic/aluminum interface? Or a weak spring combined with pulling angle that is not acute enough?

One of them I got functioning again by shortening the spring(do this only if you are prepared to curse a lot to get it back into position), but the other one is dead. The functioning seemed to get better with time. These were 2007-9 derailleurs. Don't know about later models.

I have not had these issues with the XO.

[Just Keep Pedaling]

I use a medium cage on a three ring - the shifting is better under load but when in the granny cog there are about four gears not available on the rear. Shorter cages are to avoid hooking on rocks when doing a descent.

[kosmonooit]

You can take X0 completely apart to do maintenance on, the pins on the quad has circlips. X9 has riveted pins.

 

There was a production problem with some X9, which made them sticky. I had two (new) duds but eventually got them sorted (no thanks to Solomon Cycles ).

Edited January 26, 2011 by kosmonooit