Chain jumps off
10-09-07, 08:33 AM
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Chain jumps off
Hi everyone, I have a chain question.
My errand bike is a 96 Schwinn Cruiser Supreme. It's got a 6-speed Shimano HG-22 freewheel on the rear, one chainring on the front. Derailleur is a Shimano SIS, I think it's a Tourney. Twist-grip indexed shifter. It's cheap basic stuff but works fine for a utility bike - with only one problem.
Every now and then, when I shift gears the chain jumps completely off the front chainring. Yesterday I was shifting from 3 to 4 (in other words from a lower to a higher gear) and the chain came off toward the outside, in other words in the direction I was shifting it. The chain was completely off the chainring, but it was engaged in the correct cog on the freewheel.
Unfortunately I can't predict when the problem will happen, and I can't get it to happen on the workstand. My first thought was a worn-out chain but chain wear looks OK, well below the .75% threshold.
Any ideas where I should start looking? Yes, I could take it to the LBS but I'd rather figure it out and fix it myself.
I'd appeciate any help or insight, thanks.
My errand bike is a 96 Schwinn Cruiser Supreme. It's got a 6-speed Shimano HG-22 freewheel on the rear, one chainring on the front. Derailleur is a Shimano SIS, I think it's a Tourney. Twist-grip indexed shifter. It's cheap basic stuff but works fine for a utility bike - with only one problem.
Every now and then, when I shift gears the chain jumps completely off the front chainring. Yesterday I was shifting from 3 to 4 (in other words from a lower to a higher gear) and the chain came off toward the outside, in other words in the direction I was shifting it. The chain was completely off the chainring, but it was engaged in the correct cog on the freewheel.
Unfortunately I can't predict when the problem will happen, and I can't get it to happen on the workstand. My first thought was a worn-out chain but chain wear looks OK, well below the .75% threshold.
Any ideas where I should start looking? Yes, I could take it to the LBS but I'd rather figure it out and fix it myself.
I'd appeciate any help or insight, thanks.
10-09-07, 10:06 AM
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Jumping Chain Problem
My experience is that the chain starts jumping
(actually, hanging up on gear teeth) when it's
dirty from an accumulation of oil and dirt on
the chain and sprockets.
Try cleaning and reoiling them.
(actually, hanging up on gear teeth) when it's
dirty from an accumulation of oil and dirt on
the chain and sprockets.
Try cleaning and reoiling them.
