Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 2 Post(s)
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If the chain runs well on inline combinations but runs over the side when feeding from the more extreme angles you have a few choices.
1- check chainline, and/or and consider moving it towards the problem side to improve the line from that side. In your case inboard a few millimeters. Note that might worsen chain retention when feeding from outside angles.
2- live with it and avoid using the problem combinations
3- replace the chain with one having larger plates or more bellmouth inside the inner plates to improve it's ability to track when feeding from an angle.
4- replace the chainring with an ungated one, since the shift gate is usually the point where the derailment starts.
5- trim the FD so the the inner plate pushes the chain over marginally to help keep it on. This is hard on the FD, and only vialble if for very short term use situations.
6- modify the chainring tooth profile, which is something old school mechanic have done since the early days of derailleur bikes when chains falling off was the rule not the exception. This is the best solution because it solves the problem without causing other complications.
Here's a link to a prior response
I posted for someone with a similar problem. It's post #4, start from the second paragraph.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions”
- Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance
Last edited by FBinNY; 09-10-10 at 10:01 AM.