Bent Chain ring.

theunmarkableb

After a crash at the weekend my bike was making some strange gear noises from the Crankset. On closer inspection it appears that I’ve slightly bent the big chain rings. The bike is a 3 month old Specialized Epic Comp FSR. The website lists the crank, Derailleur and rings as follows.

FRONT DERAILLEUR
Shimano M660 SLX, DMD, top swing, dual pull
CRANKSET
Custom Shimano FC-M542, S: 170mm, others: 175mm
CHAINRINGS
44A x 32A x 22S, 4-bolt, 104/64mm

Do I need to just buy the same part again? Do I just buy a Shimano 44A 4 bolt ring or can I upgrade to an XT or XTR ring or can I use an SRAM ring? I’ve only recently got back into biking again and I’m out of touch with what is compatible with what these days. I’d certainly be keen to get something lighter and stronger that gave better shifting performance if that were an option.

Any advice on my best next move would be appreciated.

Thanks

nicklouse

most shimano big rings with the right BCD 104mm will fit, but if it does not it is nothing a little filling will not sort.

theunmarkableb

Thanks. Is there any advantage in me going for a better ring over what I already have? will it shift better?

theunmarkableb

Hey by the way that comment in your post signature. I have a Jason McRoy poster from Bike 96 that says the same thing on it. is that where you got it from?

beverick

Can't see why a bent chainring would cause a noise from the crankset. You may have done something to the BB or bearings.

Is the noise coming from the chain rubbing on the deraillure? If so you may be able to 'adjust' out the noise.

The main problems I had when I bent the outer chainring on my hybrid last year was that every now and again, the chain dropped, and jammed, between the middle and outer rings on (mainly but not exclusively) up-changes.

The attached may help with diagnostics and/or the quest for replacement parts. The Shimano site (and tech docs) also gives details of what's compatible with what.

If you need to upgrade, I can recommend the Deore XT M770:
http://www.chainreactioncycles.com/Mode ... elID=20679

(Especially with the XT-M770 shifters.)

Bob

theunmarkableb

Thanks. I couldnt see the attatchment though how do I access it?

The chain ring is bent in and when I'm in middle ring and the 2 smallest sprockets theres a noise as I pedal. at the same part of the rotation. The only thing I can think is that the side of the chain is catching on the bent part of the big chain ring. It does scrape against the derailier too when I'm in the big ring but I cant adjust it out without affecting the shift.

Thanks for the help though.

captainfly

I pic of the damage would be good, if the ring isn't too badly bent the you might be able to straighten it out off the bike, either with a vice or even a hammer, but any 44t outer ring with the correct bolt pattern will do the job.