Chain jumps off front chainring

[Smitty]

Any ideas as to the cause of a chain jumping off the front chain ring, especially when putting power on a climb? I thought at first it was an issue of my chain being too long. I took a link out and the derailleur is now parallel in the two small chainring configuration, but am still having the problem with the chain jumping off. I am not sure how much more abuse my shins can take. Any help will be appreciated.

[Greg]

Try checking your chaingrings for missing or bent teeth. That's what happened to me.:eek: :eek:

[been_jammin]

sounds like chain suck - condition caused by hooked/bent/worn chainring teeth

other possible causes in my experience: chainline out of tolerance, chainring installed backwards (I did it), loose/missing chainring bolts, extremely dirty/dry chain

my advice, for what it's worth: clean/lube chain, check/tighten chainring bolts, inspect chainring for teeth that look hooked like a shark's dorsal fin... if all else fails, see Carlos at BikeShow or your favorite wrench at an LBS

[carlos]

i'd have to agree with ben and greg. sound like a worn ring. it may also have a bent or broken teeth.

sounds like it's time for a new chain.

swing by your favorite LBS and ask them to throw the chain checker on there and BAM!

usually if it happens under load then it probably means the teeth on the ring aren't holding the chain or the chain is stretched/worn to the point that, the wear, combined with the worn ring, is causing slippage.......resulting in a skip when you pedal.

[joetoeclips]

You could just climb in the middle ring - problem solved

[Weegster]

Originally posted by carlos
throw the chain checker on there and BAM!


Hmmmmmm...My Chain Checked goes "Ker-Blooey!!":D

[carlos]

but does it go Zzzzzzzzzz?

[Weegster]

Originally posted by carlos
but does it go Zzzzzzzzzz?

No Carlos...I'm sorry to say that the only "Zzzzzz" from my "Battle-Axe" is when the Playing Card & Clothespin combo get knocked askew in the spokes...:D

[Jeff]

Just got back from the bikeworld on blanco. Got two rings real 26 t 74 bc and a ringle 58/22. guy says I need to know if my bike can take a 71 bc and it should say on my bike . Where should it say on my bike and which one is for it. The bike. Wife calls it the trek purple people eater nimbus 7000. Meaning trek 7000. Shimano exxage crank . help i want to ride before dark!!!!

[carlos]

74 bolt circle diameter?

oh yeah. you should be able to just hold one chain ring up and line up the bolts.

[Jeff]

I got it fixed. Well I knew when to stop trying and go get it fixed.
I didn't have a crank puller. So i called bike world blanco back and they said bring it in and we'll fix it . They did.

An aside. Cop on the radio tells this TRUE story.
It seems their was a rave in fort worth. Chick goes, drops some x and drinks some alchohol. Gets in her car to drive home. Hits a guy whos head goes through the windshield and breaks both of his legs. So she keeps driving. Talking to the dude with his head still through the windshield as she does so he's talking back too.(surreal) Home she drives, pulls into her garage. Gets out of the car goes inside. Throughout the next 2 - 2 1/2 days she checks in on the dude with his head stuck through the windshield. Until finally he dies of bloodloss or shock or both. THEN she calls for help. Who does she call???
Friends , who help her burry the body in a city park. Dude would have lived if she'd have done the right thing. True story .


So anywho , Thanks Carlos , Bikeworld and me . My bike is doing fine.

[carlos]

the Blanco Bike World dudes are cool!

did she take pictures? no. so the lesson? always take pictures.

[joetoeclips]

Story confirmation:

http://www.cnn.com/2002/LAW/03/08/hit.and.rundeath.ap/index.html

[carlos]

hehehehee

[Jeff]

you doubted me?
:(