Mike54

Hello!
I have a 11:28, 10 speed SRAM cassette on a Giant cyclocross. I want to change to 11:32 or 34 for touring. Must I change my SRAM Rival derailleur and is there something else I must know? Thank you!
Have fun!

bradtx

It depends... SRAM Rival Rear Derailleur | Competitive Cyclist :

The SRAM Rival Rear Derailleur is available with two cage length options -- Medium and Short. The Medium has a maximum 37t chain wrap capacity and can handle up to a 32t cog. The Short cage version has a 33t chain wrap capacity and can handle a 28t cog.

Brad

Mike54

Tank you! how do I know if I have a medium or a short?

FBinNY 

Typically short cage derailleurs have the center/center distance between the pulleys in the 55mm range (varies by brand) and medium cages are roughly 70-75mm on centers.

More to consider.

Generally RDs have the identical body regardless of cage length. Sram RDs have the upper pulley mounted on center with the cage pivot bolt, so unless the Rival is an exception it means that changing the cage will have no (zero, nada) effect on the upper pulley position and maximum sprocket capacity (regardless of what the spec. says). So the ONLY consideration is chain take-up capacity.

If you measured your chain based on the big/big+ method, you'll need a longer chain to accommodate the larger sprocket, but there's an excellent chance you can keep the RD, especially if you're willing to forego using the inner with the smallest few rear sprockets. I'd say to hang on to your dough, replace the cassette and chain measuring according the big/big+1" method which sets the shortest safe length, adjust the B-screw to clear the sprocket and see how it goes.

BTW- if small/small take up is marginal, you can improve it slightly by using a larger lower pulley. This will probably give you about another tooth or so of take up.

Al1943

You will need to stay with a SRAM brand derailleur to be compatible with the rear shifter.

zukahn1 

Yes the OP will need to stay with the same type SRAM DR for correct indexing most SRAM setups will handle a 30 or 32 big cog in the rear but likely not a 34. Also if the OP is fine with not being able to run few of the small gears with inner triple they may want to consier running a slightly smaller inner chainring.

FBinNY 

True, he has to stay within brand, but the question is whether or not he has to replace at all. I expect that he can probably get by with minor finagling and possibly accepting some limitations on small/small use.

zukahn1 

+1 I would expect they can get by with the current DR if they are willing to possible accpet some limitations on small/small and maybe big/big use.

FBinNY 

IMO limitations on big/big use are NEVER acceptable. (emergency repairs being the exception to all rules). The consequences of accidentally shifting into a combination that the chain cannot loop are too severe. I'd sooner accept limiting the use of the inner chainring to the top 3 or 4 rear sprockets than risk the risks of a too short chain.

Mike54

I thank you all for your answers. I have A short derailleur. So what do I choose? I will start a new post.

Al1943

Your answer is in posts #2 and #5 , the SRAM Rival medium cage will run a 32 big cog.

bikepro

+1
I destroyed a Red RD like this. I didn't realize I was beyond the RD's capacity. I recommend the Force or Red WiFli RD. It's designed for 50/34 compact rings and Sram's 11-32 cassette. I use one with a Shimano 12-30 cassette with no problems.

Mike54

Thank you, I know, but since I have to change maybe I should upgrade a little?

Mike54

Does any one know, if I could A mountain derailleur like the X9?

FBinNY 

This is the $60 question. You might not HAVE to change. But whether you have to or just want to, your]\'re right that an upgrade makes sense at this time. Check your total take up requirements -- the sum of the differences big and smallest front and back --- and buy something with that or more capacity. I don't know the Sram line or prices these days, but maybe a Force might make sense if the price difference isn't large.