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Discussion Starter · #1 ·
I have a 2017 Cervelo C3 11sp Ultegra mech group. When I ride I will get a occasional clank from the chain ring. It typically does it after coasting a bit then peddling.

It used to do it maybe once in a 20 mile ride but I just went on the first ride of the season and it was happening several times a mile.

I just got a new wheelset and new cassette and the clank seems to be coming from the rear too.

This past winter I used a trainer a couple of times and removed and put the rear wheel back on so maybe the chain got bent.

What could it be? Is it possible the chain got bent a little causing the clank?

Also, last year I noticed the chain ring bolts were loose so I tightened them using a torque wrench to the amount it showed. I was hoping that was the cause but it did not seem to make a difference.

Thanks
 

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I'd start by checking and verifying that the cassette is tight and properly torqued. Verify the FD cage clearance with the crank arm when in the large chainring. Next move onto the BB/NDS crank arm and pedal/cleat engagement.
 

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Just a clank. When it's under load it seems fine.
Check your cranks very carefully for cracks and/or separation. There are many failure reports out there for the newer Shimano Hollowtech "4 arm" cranks at Ultegra and Dura Ace level, but not 105.
 

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Discussion Starter · #6 ·
I should have mentioned that Cervelo put Rotor cranks and the rest of the group is Ultegra.

I'll check them out though.

Thanks
 

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This is due to your cassette hiting the splines of the freehub body. This can happen when 1) you start to pedal after coasting, 2) during rear gear changes (especially from big cog to smaller cog).
In both of these situations, the noise arises because the cassette makes a hard impact onto the freehub body. Furthermore, the noise tends to get amplied when using carbon deep wheels. Using shallow aluminum wheels you tend not to notice the noise becasue shallaow aluminum wheels don't amplify the noise as well.

And you don't hear this noise under load because during underload, the cassette is firmly pressed agaisnt the freehub body.

This is one reason why the freehub body get chew up.
 

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I have a 2017 Cervelo C3 11sp Ultegra mech group. When I ride I will get a occasional clank from the chain ring. It typically does it after coasting a bit then peddling.

It used to do it maybe once in a 20 mile ride but I just went on the first ride of the season and it was happening several times a mile.

I just got a new wheelset and new cassette and the clank seems to be coming from the rear too.

This past winter I used a trainer a couple of times and removed and put the rear wheel back on so maybe the chain got bent.

What could it be? Is it possible the chain got bent a little causing the clank?

Also, last year I noticed the chain ring bolts were loose so I tightened them using a torque wrench to the amount it showed. I was hoping that was the cause but it did not seem to make a difference.

Thanks
I had a noise and noticed my front derailleur was coming loose from the braze-on. Just something else to check
 

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I also have a similar sound on my tandem.
After investigating several areas (crank bolts, bearings, pedals) I discovered the cassette is loose (it can slide back and forth). I have not determined yet if the lock nut is loose or if it is missing a washer but I am suspecting the latter.
So yes, check the cassette.
Had my second COVID shot yesterday and it looks like I be spending most of today on the couch so probably will not get to it today.

Good Luck
 
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