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why is there a really loud clunk from the rear of my mtb when i go over small bumps??

1328 Views 6 Replies 6 Participants Last post by  Gym123
I recently bought the Marin Alpine Trail 7 secondhand and is perfect and everything runs smoothly except there is a really annoying clank/clunk (definitely from somewhere on the rear of the bike) every-time i go off a kerb, down a bumpy track or when i go over bumpy berms. I don't hear the noise on really slow technical rock gardens but when i get faster then fast-walking/jogging pace it starts to become really noticeable on any bumps. When going downs a fast single track or any fast trails with rocks it sounds like something is about the just fall off.

I know for a fact its not that the bushings are needing replacement on my rear shock because there is no movement near my linkage. The chain is very loose when i am in the hardest gear but gets more tight the more easier the gears, the chain isn't really stretched because the bike shop said to wait a few more months before replacing it.

My right crank-arm has a little-bit of play when in a certain position but otherwise I have no clue what could be causing this clank when i go over small bumps.

Any ideas what could be the problem? What is making the noise? What I should look out for? What I should do?

Thanks a-lot :)
1 - 7 of 7 Posts
Park Tools has a video on YouTube that shows the reason for this- it could be caused by the freewheel or cassette hub being loose.
Get the service manual and torque the drivetrain and suspension bolts to spec.
Is it tubeless setup? Check to see if the sealant has dried up into a rubber creature of sorts in the rear tyre.
Is the derailleur clutch turned on? Chain slapping around?

Could be all sorts of things and hard to diagnose without seeing anything. If not something simple like above, I'd look at the rear wheel and the suspension and go over every bolt to make sure it's tight. Your lucky it's not a squeak because then it could be literally anything.

Edit: didn't realize I was on second page and this was already a month old. Did you get it figured out?
Is it tubeless setup? Check to see if the sealant has dried up into a rubber creature of sorts in the rear tyre.

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1 - 7 of 7 Posts
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