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chain falling off small ring(8 posts)

chain falling off small ringpkompath
Jul 28, 2002 3:33 AM
A disaster has happened. Well, it's been happening for the last 3 wks. It seems only on climbs does the chain come off the small ring/big cog ratio. The exertion somehow might be the cause--but who knows. Now, the chain is completely ruined. The inner plate bent off the pin, thus making it impossible to pedal. Do I need a new chain or are the limits off for both rear and front der.? Also, the rear der. was touching the spokes when in the small ring/big cog combo.
re: chain falling off small ringXoc
Jul 28, 2002 5:25 AM
Sounds like the limit screws need to be adjusted on the bike. Take it to a bike shop and have them replace the chain and tune it up for you. Adjusting derailleurs isn't difficult, but if you've never done it before it can be tricky.
Was it ever right?Spoke Wrench
Jul 28, 2002 6:56 AM
If it was right once and you havn't had somebody screw up the previously OK adjustments, I'm betting you need a rear dropout alignment. It's not too hard to bump something hard enough to upset the alignment which can cause both the chain to unship and the derailleur to "tick" the spokes. That's probably going to be an LBS job. Plan on spending about $25.00 plus the cost of a new chain.
Low gear limit screw..DINOSAUR
Jul 28, 2002 8:41 AM
Sounds like the low gear limit screw on the front der. Should be the one closest to the frame when you are looking straight down on the bike. Make small 1/4 inch turns in a clockwise direction intil it drops on the small ring with no problems. Then test ride your bike under load and make sure it shifts O.K.

Could also be the way you shift. I had this problem a couple of times and discovered it was because I was spinning too fast and shifted too soon into the small ring and the chain would just bounce off the small ring. You want to wait until you feel the need to shift to the small ring then ease up on the tension before you shift.
Low gear limit screw..pkompath
Jul 28, 2002 12:50 PM
I was already in the small ring/large cog, thus no shifting.
Low gear limit screw..DINOSAUR
Jul 28, 2002 8:48 PM
Sorry, I misread your post. Sounds like your rear dropouts are out of alignment and you need to take your bike to a shop and have someone go over it for you.......
Rear dropout-out of alignment? (NM)pkompath
Jul 29, 2002 5:10 AM
Rear dropout-out of alignment? (NM)Spoke Wrench
Jul 29, 2002 6:32 AM
That's where the rear derailleur bolts onto the frame. If it gets bent inward even a little, and that's easy to do, the derailleur cage won't be vertical which can both upset the shifting and cause the bottom of the derailleur cage to "ting" the spokes. Shops have a special tool that bolts onto the bike frame in place of the rear derailleur and is used to finesse the dropout into alignment.