SRAM Red Black front mech chain rub

richiegwy

I have sram red mechs running with a compact chain set and am having chain rub in the bottom 2-3 sprockets when in the small chain ring and the top 2-3 when on the big chain ring.
I have messed with both adjustment screws but with no success ( rubbing on the other end if I open them out)
Firstly is this amount normal or is there something wrong?

Any suggestions on how to improve it?

Would the new yaw front mech improve things?

StillGoing

SRAM front derailleurs are designed to run on the full range of the cassette without rubbing. Sounds like you've not set the rear derailleur H & L adjustment right if the front has been aligned correctly?

edten

Release the cable and start again.
Put chain in big sprocket and inner ring. Adjust front mech limit screw so .5mm clearance between chain and mech cage. Attach the cable tight. Flick gear lever how many times you should for the chain to change up, with campag its 3 times not sure about SRAM. Chances are there wont be enough cable tension yet for the chain to shift to big ring.
Adjust the tensioner on the down tube or the inline cable adjuster if you have inframe cable routing. Keep turning to tighten the cable whilst flicking up and down the front mech until the chain changes up cleanly. Check there is still cage clearance when in big sprocket & inner ring. Put the chain on little sprocket at the back and with the chain in the big ring use the limit screw to set the cage so about .5mm clearance with the chain. This works fine with campag and shimano. Not sure with SRAM.

edten

For some reason it's 'starred' out flick ing ?? Last time I looked this wasn't a swear word!

richiegwy

philthy3 wrote:

SRAM front derailleurs are designed to run on the full range of the cassette without rubbing. Sounds like you've not set the rear derailleur H & L adjustment right if the front has been aligned correctly?

If the rubbing is happening in the front cage can the H & L on the rear mech influence that? I didn't think it could

StillGoing

If you're getting interference on the front derailleur in both the large and small sprockets then, yes the derailleur may be faulty if the interference is from the same place i.e. from the rear of the derailleur. The limit screws on the rear just align the jockey wheel under the smallest (H) and largest (L) sprockets on the cassette. The B screw sets the jockey wheel distance from the sprockets, but I'm sure you already knew this. If so, then yes the front derailleur must be the issue. I'd check the alignment with the chain in the big ring and large sprocket. There should just be enough clearance on the front derailleur. Then check it in the small ring and the small sprocket. Again there should be just enough clearance if the limit screws on the front have been set correctly. I know people will go on about cross chaining, but nevertheless, SRAM is designed to allow you to do this without chain rub.

sungod

i) check the cage is parallel to the chain rings, also check cage/rings aren't bent
ii) check the cage is the correct height wrt to the big chain ring
iii) then adjust l and h limit screws, as others have said, you should be able to adjust for no chain rub, or at least only a bit at the most extreme angle when on biggest-smallest

sram's instructions are here...

http://cdn.sram.com/cdn/farfuture/c90h_cmBDSLTzF4-6kzVRNS03c6ToapPH_dJcVIBQ44/mtime:1297962106/sites/default/files/techdocs/95-7915-010-000%20Rev%20B%20-%20Road%20Derailleurs_6.pdf