[Jakethomascampbell]

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

 

[mtnbkrmike]

Dude - no more spamming. Ask your question on one subforum only. So far you have hit 4. And who knows if you are done. Stop. Breathe. Wait for a response or two.

 

[Sparticus]

Probably a clutchless derailleur allowing chain slap.
As for your loose crank, fix that pronto or it'll wallow in short order and presto -- new crank time.
=sParty

 

[Jakethomascampbell]

Probably a clutchless derailleur allowing chain slap.
As for your loose crank, fix that pronto or it'll wallow in short order and presto -- new crank time.
=sParty

thanks for the help, it has and clutch and has been on so cant be that and yes, i just tighten the crank to make sure I don't have to spend more money on cranks and hospital bills!

 

[r-rocket]

Very difficult to diagnose over the internet. What year is the bike? Here are some other random guesses of what can cause clunks:

Rear wheel bearings way too loose (Hold the bike and see if there is a lot of play if you move the wheel side to side.)

"Maxle" quick release not tightened hard enough before flipping the lever (that specific quick release can be tricky)

Crack anywhere in your frame, even the front triangle can sound like it is coming from the back. It can make a loud clunk when the crack opens on a bump, then slams shut again.

 

[Harold]

worn shock bushings are another possibility

 

[Jakethomascampbell]

worn shock bushings are another possibility

I got taught how to check that and thats not the problem thankfully (expansive fix)

 

[Jakethomascampbell]

Very difficult to diagnose over the internet. What year is the bike? Here are some other random guesses of what can cause clunks:

Rear wheel bearings way too loose (Hold the bike and see if there is a lot of play if you move the wheel side to side.)

"Maxle" quick release not tightened hard enough before flipping the lever (that specific quick release can be tricky)

Crack anywhere in your frame, even the front triangle can sound like it is coming from the back. It can make a loud clunk when the crack opens on a bump, then slams shut again.

thanks, the rear wheel has a little bit of play from side to side but only a little bit, could this be the reason? its a 2021 marin alpine trail 7.

the bike shop says the chain isn't stretched but by the end of the cassette the chain is barely on it (photo below)

the derailer has a little bit of play and is this normal??

 

[DIRTJUNKIE]

Dude - no more spamming. Ask your question on one subforum only. So far you have hit 4. And who knows if you are done. Stop. Breathe. Wait for a response or two.

Get that man a paper bag to breath into stat.

 

[Steel-Onions]

I had a 'clack/knock' noise from the back of a bike whenever compressing the rear end, turned out to be a sticking clutch in a new XT derailleur, greased the clutch barrel and noise went away, can try pushing the derailleur forward with the clutch 'on' to rule it out

 

[phantoj]

The noise is coming from the rear

 

[belastee]

Check your rear axle, it maybe completely broke at the jonction of the hub and the cassette !!!
With the thru axle, all stay together at normal load, but when things get rougher, it's will generate some bizarre sonds.
Remove your thru axle and the wheel, the cassette may fall on the ground.
I had that issue two times with aluminium rear axle from Stan's hub.
I replace the axle with the steel version.

 

[bingemtbr]

Is the shock bottoming out?

I had a similar issue last month: the bike made noise intermittently under certain riding conditions. Sounded like it was coming from the rear triangle. Took the bike into the LBS for a brake bleed and asked them to check the pivots and shocks.

Pivots: great condition.
Shocks: Needed a little TLC but they hadn't been serviced in 10mos.
Oh...the pivot/shock bolt on the lower VPP link was broke.

I regularly check all pivots and fasteners. I did not catch this one. The bolt had failed 1/2 through its threads. So while it was snug it still had enough play under pressure to create the audible noise.

 

[Ksanman]

Could be a rim strike, you might be running too low psi in the rear...

 

[Coal-Cracker]

Could it be internal cable routing rattling inside the rear triangle of your frame? You'd be surprised at how much noise this can make.

Sent from my SM-G973U using Tapatalk

 

[Jakethomascampbell]

I had a 'clack/knock' noise from the back of a bike whenever compressing the rear end, turned out to be a sticking clutch in a new XT derailleur, greased the clutch barrel and noise went away, can try pushing the derailleur forward with the clutch 'on' to rule it out

nah, the derailleur doesn't have any play except from side to side on the hardest gear but it makes no noise when i move it

 

[r-rocket]

thanks, the rear wheel has a little bit of play from side to side but only a little bit, could this be the reason? its a 2021 marin alpine trail 7.

the bike shop says the chain isn't stretched but by the end of the cassette the chain is barely on it (photo below)

the derailer has a little bit of play and is this normal??

View attachment 1959456 View attachment 1959457

A very little amount of play from the axle bearing measured at the rim would not cause a clunk.

Measure the chain with a chain stretch tool, that's the only way to know for sure. That first picture is a bit worrying. Check the chain for tight links too. The links should all turn freely at each pin, but I doubt that is related to the clunk.

The derailleur should have play in the wheels, but not in the knuckles. Some play at the pivot by the mount is OK.

In your original post you said "The chain is very loose when i am in the hardest gear " Is the front chainring a 32T ring like it came with stock? Sometimes when people put on smaller chainrings the chain length needs to be changed (number of links, not the amount of stretch in the chain.) Measure the chain first with a chain stretch tool to make sure it isn't stretched, then go through Shimano's steps to measure your chain length. There is a specific way to measure for shimano 12 speed. I like how this guy explains it.

How to calculate correct chain length on a Shimano 12 Speed drivetrain

dansbikeblog.com

The noise could be chain slap, but most folks don't describe chain slap as a clunk.

 

[Jakethomascampbell]

A very little amount of play from the axle bearing measured at the rim would not cause a clunk.

Measure the chain with a chain stretch tool, that's the only way to know for sure. That first picture is a bit worrying. Check the chain for tight links too. The links should all turn freely at each pin, but I doubt that is related to the clunk.

The derailleur should have play in the wheels, but not in the knuckles. Some play at the pivot by the mount is OK.

In your original post you said "The chain is very loose when i am in the hardest gear " Is the front chainring a 32T ring like it came with stock? Sometimes when people put on smaller chainrings the chain length needs to be changed (number of links, not the amount of stretch in the chain.) Measure the chain first with a chain stretch tool to make sure it isn't stretched, then go through Shimano's steps to measure your chain length. There is a specific way to measure for shimano 12 speed. I like how this guy explains it.

How to calculate correct chain length on a Shimano 12 Speed drivetrain

dansbikeblog.com

The noise could be chain slap, but most folks don't describe chain slap as a clunk.

thanks for your help, i ended up resolving the loud clunk that i posted this for by taking the rear wheel to my local bike shop and had the cassette tightened which resolved it.

It still has the stock chainring on. the chain seems way too long but following the website its fine, and also after a while of fiddling with the tension screw and limit screws on my derailleur i managed to take a bit of the slack out of the chain. the chain isn't stretched but still sits on the cassette weirdly but i guess i will worry about that when it becomes a problem.

 

[Steel-Onions]

result !

 

[DIRTJUNKIE]

result !

He’s still working through the “could be’s”.