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why is there a really loud clunk from the rear of my marin alpine trail 7 when i go over small bumps??

2293 Views 10 Replies 6 Participants Last post by 2021Mach6, Dec 3, 2021

Jakethomascampbell

Discussion Starter · Dec 2, 2021

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

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Shark

· #2 · Dec 2, 2021

Check this post

where is the really loud clunk from the rear of my mtb...

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...

www.mtbr.com

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HuckingKiwi

· #3 · Dec 2, 2021

First you need to fix the crank. If the right crank arm is loose it can wear the spline interface and may even become unfixable if ridden like that for too long.

Noise at the rear of the bike can originate from many locations. But first make sure that the things listed bellow are not the issue.

1. Make sure that the rear thru axle is properly torqued (usually 10Nm)
2. Is the derailleur clutch ON? (I'm asking this because you said the chain was loose)
3. Grab the dropper post with your right hand and the tire with the left and pull back and forth to feel for play in the pivots or wheel.
4. Is your cassette lock ring properly torqued? (A loose cassette makes a ton of noise)
5. Is your derailleur properly fastened to the hanger?

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Jakethomascampbell

Discussion Starter · #4 · Dec 2, 2021

HuckingKiwi said:
First you need to fix the crank. If the right crank arm is loose it can wear the spline interface and may even become unfixable if ridden like that for too long.

Noise at the rear of the bike can originate from many locations. But first make sure that the things listed bellow are not the issue.

1. Make sure that the rear thru axle is properly torqued (usually 10Nm)
2. Is the derailleur clutch ON? (I'm asking this because you said the chain was loose)
3. Grab the dropper post with your right hand and the tire with the left and pull back and forth to feel for play in the pivots or wheel.
4. Is your cassette lock ring properly torqued? (A loose cassette makes a ton of noise)
5. Is your derailleur properly fastened to the hanger?

Firstly thanks for you help,
I fixed the cranks and went through steps 1, 2, 3 and 5 and they were all correct its just i don't have the correct tools for the 4th step so do you know if there is anyways to check if its loose without the correct tool

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HuckingKiwi

· #5 · Dec 2, 2021

You could try to wiggle the cassette back and forth with your thumbs but that can only show if the cassette is severely loose. Even if you don't feel movement it can still create noise if the lock ring is not properly torqued. If you really want to check it properly you will need the park tool FR-5.2 for the locking.

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Jakethomascampbell

Discussion Starter · #6 · Dec 2, 2021

HuckingKiwi said:
You could try to wiggle the cassette back and forth with your thumbs but that can only show if the cassette is severely loose. Even if you don't feel movement it can still create noise if the lock ring is not properly torqued. If you really want to check it properly you will need the park tool FR-5.2 for the locking.

yeh, i did this and doesn't make any noise or seem to be loose, any-other ideas or things i could do??
thanks

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Grinchy8

· #7 · Dec 2, 2021

Can you repeat the noise by dropping the rear of the bike. Or by pedaling and braking with the bike in a stand or upside down?

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Jakethomascampbell

Discussion Starter · #8 · Dec 2, 2021

Grinchy8 said:
Can you repeat the noise by dropping the rear of the bike. Or by pedalling and braking with the bike in a stand or upside down?

It makes the noise when i drop the rear of the bike. makes the noise while i am pedalling over bumps or hitting the brakes over bumps, if i pedal on smooth ground or brake on smooth ground there is no noise. same if i not pedaling or braking (no noise on smooth, noise on bumps)

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copylatte

· #9 · Dec 2, 2021

Jakethomascampbell said:
It makes the noise when i drop the rear of the bike. makes the noise while i am pedalling over bumps or hitting the brakes over bumps, if i pedal on smooth ground or brake on smooth ground there is no noise. same if i not pedaling or braking (no noise on smooth, noise on bumps)

Sounds like a loose cassette to me. Not sure what kind of cassette you are running but I have a microshift advent x cassette that is so loose on my hub it rattles / clanks all the time despite tightening correctly.....

Might also be a loose rear brake caliper so I would check those bolts for torque as well but more likely coming from cassette...

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Jakethomascampbell

Discussion Starter · #10 · Dec 3, 2021 (Edited)

copylatte said:
Sounds like a loose cassette to me. Not sure what kind of cassette you are running but I have a microshift advent x cassette that is so loose on my hub it rattles / clanks all the time despite tightening correctly.....

Might also be a loose rear brake caliper so I would check those bolts for torque as well but more likely coming from cassette...

i don't have the correct tools for tightening the cassette but checked if its loose. if i hold the hardest cog and the easiest cog and move them it has only a little bit of play, like 2mm, could this be the problem?

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2021Mach6

· #11 · Dec 3, 2021

Jakethomascampbell said:
i don't have the correct tools for tightening the cassette but checked if its loose. if i hold the hardest cog and the easiest cog and move them it has only a little bit of play, like 2mm, could this be the problem?

There shouldn't be any play, especially if you're just using your hands. Any bike shop should be able to check that out real quick for free.

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