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Tandem crank knocking - help with cause and cure

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Tandem crank knocking - help with cause and cure

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Old 07-04-06, 09:32 AM
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Tandem crank knocking - help with cause and cure

Hi there, looking for some ideas on cause and cure for 'knocking' on Burley Rock n Roll tandem.

Symptom - intermittent 'knocking' which seems to be related to crank rotation. Feels like it's related to captain's bottom bracket or crank/timing chain setup. Happens about same point in each crank rotation.
Most pronounced when cranking without putting too much power in and seems to almost disappear when powering hard on the cranks.

Any ideas? I'm stumped and don't know where to start!

Stuart
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Old 07-04-06, 09:50 AM
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I'd try a loose bottom bracket, worn bottom bracket bearings, loose crank arm, worn pedal bearings to start.
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Old 07-04-06, 12:46 PM
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Check out the relationship between the captain's seat and the stoker's handlebar & stem.

Actually, I have a similar issue with my own tandem and that's my next avenue to research.
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Old 07-04-06, 10:19 PM
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I had a problem similar to this on an older Peugeot tandem. I think that the problem was caused by the 2 cranksets being set out of sync plus possibly some chain problems with a left and right side chains. It could also be as simple as a pedal problem that knocks every revolution at the same point. As noted above, check the bb for tightness.
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