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Chain jumping chainring

Old 09-21-23, 07:26 PM
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Need41speed
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Chain jumping chainring

I have a Dahon Mu P8 folder with a single 53T chainring in front & a 34T-11T cassette. When I shift from the 6th sprocket to the 7th, the chain will jump & lodge between the chainring & the outer chain keeper. The space between the chainring and the keeper is wide enough to make it difficult to re-engage the chain on the chainring when I shift to the 1st sprocket. is there a way to reduce the gap to prevent the chain from jumping?

Last edited by Need41speed; 09-21-23 at 07:27 PM. Reason: grammar
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Old 09-21-23, 07:42 PM
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Originally Posted by Need41speed
I have a Dahon Mu P8 folder with a single 53T chainring in front & a 34T-11T cassette. When I shift from the 6th sprocket to the 7th, the chain will jump & lodge between the chainring & the outer chain keeper. The space between the chainring and the keeper is wide enough to make it difficult to re-engage the chain on the chainring when I shift to the 1st sprocket. is there a way to reduce the gap to prevent the chain from jumping?
According to their website itís supposed to be a 52T? (And a 32T) Has that been changed?

How old is the chain?
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Old 09-22-23, 12:17 AM
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Originally Posted by choddo
According to their website itís supposed to be a 52T? (And a 32T) Has that been changed?

How old is the chain?
While doing a tuneup for the century ride this week, I cleaned & lubed the drivetrain, I disassembled the chainring and chain guard. (Chainring is 53T, cassette is 32-11T) The chain guard was somewhat bowed so, I gently tweaked the arms and when the front end was reassembled, there was much less of a gap between the ring and guard. The chain is original equipment so will probably get a replacement at a LBS before the ride.
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Old 09-22-23, 02:02 AM
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Ok so if that model is supposed to have a 53 maybe the chainguard is the right diameter.

Speculating but maybe the chainís excessively worn, making it easier to fall off (the links ride up the teeth) and has also been pushing more against the guard when in the top gear because of it - Iíd expect some pretty horrible noise if so though. But something must have bent the guard.
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Old 09-22-23, 07:56 AM
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Is there a shop there that deals with Dahon's? Particularly if the shop's owner is the mechanic, I've never gotten out of a shop without a hour or so worth of conversation that can include useful things to know about a problem I might be having. And if I have my bike with me, they will often take a look and offer all sorts of advice for free.

Maybe you should go talk up your Dahon dealer!

Buy some gloves, bottles or something if the talk is good. Even if it didn't help your current issue.


You do pedal when you shift don't you? I've seen some that stop pedaling then shift. They somehow think that no pressure at all can be on the chain when shifting. And that's very incorrect. Chain shouldn't be coming off at all. So the big question is if that plate is supposed to prevent that or just be a guard to keep your pant leg from getting caught and grease off your calf.

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Old 09-25-23, 10:32 AM
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Happy Ending

Completed the century ride yesterday without incident! Shifting up to & down to 7th gear. I didnít have time to get a replacement chain so apparently that wasnít the issue. Cleaning & lubing the drivetrain appears to have been the solution to the problem. Mahalo everyone for your inputs & will still probably get a new chain.
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Old 09-29-23, 02:42 PM
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Originally Posted by choddo
Ok so if that model is supposed to have a 53 maybe the chainguard is the right diameter.

Speculating but maybe the chainís excessively worn, making it easier to fall off (the links ride up the teeth) and has also been pushing more against the guard when in the top gear because of it - Iíd expect some pretty horrible noise if so though. But something must have bent the guard.
Chainguard diameter was not the issue. The gap between the chainring and the guard was possibly too wide. After cleaning the drivetrain & lubing the chain seems to have remedied the jumping. No noise was noticed during the problem. Mahalo for your input.
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Old 09-29-23, 02:58 PM
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Originally Posted by Iride01
Is there a shop there that deals with Dahon's? Particularly if the shop's owner is the mechanic, I've never gotten out of a shop without a hour or so worth of conversation that can include useful things to know about a problem I might be having. And if I have my bike with me, they will often take a look and offer all sorts of advice for free.

Maybe you should go talk up your Dahon dealer!

Buy some gloves, bottles or something if the talk is good. Even if it didn't help your current issue.


You do pedal when you shift don't you? I've seen some that stop pedaling then shift. They somehow think that no pressure at all can be on the chain when shifting. And that's very incorrect. Chain shouldn't be coming off at all. So the big question is if that plate is supposed to prevent that or just be a guard to keep your pant leg from getting caught and grease off your calf.
The chain jump happened under load so, pedaling was not the issue during the 6th to 7th gear shift. I did ďflattenĒ the chainguard by tweaking the arms. I thoroughly enjoy getting advice from my LBS mechanics & bounced this problem off them. Here in Honolulu, a number different shops retail folding bikes but none specialize in Dahon.

I think I fixed it w/ a drivetrain tuneup (cleaned, adjusted & lubed). There were no issues during the local weekend century ride. Mahalo for the I deas in fixing my problem.
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Old 09-29-23, 05:13 PM
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Made it 75 miles on a Dahon but never a full century. Well done!

You may consider a narrow/wide chainring in the future.

I changed the stock crankset and now have a 52T oval narrow wide chainring without the chainguide/bashguard and never have a drop.
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