# Rival Rear Der. Revision, how do I get update?



## Stratmosphere (Feb 28, 2007)

Noticed though the summer on my '07 Roubaix Expert Compact the chain coming off the idler cage(s) several times and eating the inner side of the cage each time, and the idlers.

Now I see an apparently newer version that has a much more extended idler cage which would obviously improve the defect. Anyone know of a remedy from SRAM on this?


----------



## Cyclo-phile (Sep 22, 2005)

Any idea what was causing the chain to come off of the pulleys? Have you checked that the chain isn't too long?


----------



## Stratmosphere (Feb 28, 2007)

Regardless you can see SRAM addressed an issue and I'm interested in a remedy besides replacement on my own. I can't really remember what triggered the issue. All I can think is some stalling in my pedalling action during a shift.


----------



## Cyclo-phile (Sep 22, 2005)

I doubt the longer cage is a "fix" for the issue you're describing. A longer cage is used to compensate for the longer chain required of a wide range cassette. That is to say, an 11-27 cassette requires 3 more full links of chain than an 11-21, but the chain must be taut in the 11-tooth cog on both. The longer cage helps to take up the slack in those extra links. A mountain bike derailleur has a much longer cage to compensate for the 22-tooth difference in the front rings plus the 23-tooth difference on a typical 11-34 cassette.

Can you take a photo showing how the chain dislodged from the pulleys?

Does friction in your freehub cause the chain to go slack on the top run when you backpedal quickly?


----------



## Stratmosphere (Feb 28, 2007)

The inside plate of the idler wheels was modded (enlarged, not lengthened) to address the issue. Seems to be confusion here. Chain length is to the SRAM manual. I'm sure the issue was pervasive and therefore addressed by SRAM as seen from the change in the part.


----------



## jmkimmel (Jul 13, 2007)

I had the same problem on my Rival equipped cross bike - under race conditions, the chain actually became lodged in teh cage and I tore the der hanger off by pedaling through it....oops.

SRAM replaced the der's (happened twice during the season), but charged me the $30 replacement fee. I think they normally will replace the cages on a der for free if you send it in, via warranty service of a LBS. The downside is that you're without a der for ~3 weeks.


----------



## FTR (Sep 20, 2006)

Interesting.
Had this exact same issue myself and put it down to something I had done.


----------

