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Right crank stroke making crunchy ratchety sound when in hardest gear

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Right crank stroke making crunchy ratchety sound when in hardest gear

Old 09-27-20, 04:52 PM
  #1  
Captain_Canada
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Right crank stroke making crunchy ratchety sound when in hardest gear

Hi! I'm hoping to get some help diagnosing an issue:

I'm getting a crunchy ratchety sound on my right (drive side) pedal stroke but not the left. It is very loud when in my hardest gear (big chainring/smallest sprocket) and much less loud in my second hardest gear (big chainring/second smallest sprocket). It does not make significant noise in the other sprockets.

The noise occurs in the big chainring/smallest sprocket even when I put out very little power (example-pedaling downhill).

I grabbed the crank with my hands and there doesn't seem to be any back and forth play in the bottom bracket.

When I am in the small chainring the noise does not occur at all, even if I am pushing hard (climbs etc).

Any idea what's going on?

Bike and components: Shimano 105 10 speed, Cannondale CAAD10 2014

Thank you!
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Old 09-28-20, 12:04 AM
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Pop N Wood
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My guess is something flexing so the chain is rubbing on a chain stay/frame member/front derailleur. Really hard to tell without hearing the actual sound, chains rubbing on frame members is pretty distinctive.

Make sure your front chainrings are flat and parallel. They will flex to the outside on your right pedal stroke. this could push the chain into the derailleur or rear frame member. Left pedal will flex the other direction, small ring changes the angle. Make sure your cassette ring is torqued, try adjusting out your front derailleur, retorque your chain ring bolts, tighten your pedals, look for any signs of wearing or rubbing.
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Old 09-28-20, 04:06 AM
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I'm tipping chain on FD cage. Can be hard to see, and possibly difficult to replicate on the workstand.
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