Specialized Stumpjumper clunk

Miguel75

Miguel75

Likes Dirt
hi brains trust, my mate recently (6 months ago) bought a brand new Specalized stumpjumper and really enjoys it but there’s an intermittent clunk that happens when under load.

He’s taken it back to the store and they’ve pulled everything apart, removed the BB, cranks, pulled apart the rear triangle and all pivot bolts and it still clunks way too often. The store really isn’t able to provide any answers or stop the clunk and so I thought I’d ask you lot for ideas..

Pic here;
https://m.facebook.com/photo.php?fb...d=683673045&set=a.10150385437798046&source=48
 
M

mas2

Likes Bikes and Dirt
Just fixed my brothers bike where the lower jockey wheel on the rear derailleur would skip and make a thunk every couple of rotations . As this one is new I would check the jockey wheel teeth aren’t munted. Is it shimano or sram?
 
hellmansam

hellmansam

Likes Bikes and Dirt
A super simple one is a tight link in the chain, can be revealed by rotating the cranks backwards a few turns. It will show up as it goes through the jockey wheels. Used to be quite common in new bikes with a HG joining pin in the chain. Easily fixed by flexing the offending link sideways at to loosen it up.
Might not be relevant this century, but a piece of piss to rule out.
 
Miguel75

Miguel75

Likes Dirt
mas2 said:
Just fixed my brothers bike where the lower jockey wheel on the rear derailleur would skip and make a thunk every couple of rotations . As this one is new I would check the jockey wheel teeth aren’t munted. Is it shimano or sram?
Click to expand...
It’s Sram. I’ll check these two suggestions tomorrow and report back.
 
Calvin27

Calvin27

Eats Squid
hellmansam said:
A super simple one is a tight link in the chain, can be revealed by rotating the cranks backwards a few turns. It will show up as it goes through the jockey wheels. Used to be quite common in new bikes with a HG joining pin in the chain. Easily fixed by flexing the offending link sideways at to loosen it up.
Might not be relevant this century, but a piece of piss to rule out.
Click to expand...
+1 Sounds very familiar to a 'hard link' problem I had a while ago. The commuter chain flexed but it was a fair bit stiffer than the other links and would have this wierd clunk when it came to that chain link.
 
pink poodle

pink poodle

気が狂っている男
Miguel75 said:
He’s taken it back to the store and they’ve pulled everything apart...
Click to expand...
Sure they have. Call me a cynic on this, but did he see them do this? Or are they just saying they did? Some people in the industry (as with all occupations really) do great work, others not so much.

Another big negative to rule out is cracks. I've seen it before across a few different frames where a crack will make an annoying noise on the occasions it flexes.

If the frame isn't cracked have you and he had a close look at:
- Pedals
- Crank
- Bottom bracket
- Rear hub
- Chain as mentioned


The head set as well. Could need the cups popped and refitted.
 
Miguel75

Miguel75

Likes Dirt
Thanks for all the help gang. It seems we’ve localized the clunk to the rear wheel. It’s either a dodgy bearing or cassette.

We tried different rear wheels and couldn't replicate the issue, so took a closer look at the offending rear wheel and found there’s a little side to side slop when wiggling the cassette on the free hub. The lock ring is tight and at present we can’t figure out if it’s the hub bearings, free hub or cassette... either way it’s going back to the shop next week.
 
Miguel75

Miguel75

Likes Dirt
Update;
My mate emailed the bike shop last Sunday, while we were still at Bright, to let them know the clunk was still happening and that we’d been able to identify the rear wheel as the culprit. The bike shop replied and asked him to bring the bike in for them to look at again, for the fourth time. So he drove from Eltham to Port Melbourne (approx 1.5hrs return).

Bike shop “identifies” the issue, replaces a “part” and says all fixed though they can’t tell my mate the part they replaced. Bike doesn’t make clunk while testing in parking lot but starts as soon as he gets home to Eltham....

The bike is a high end carbon Stumpy that cost a fair chunk of change. Add to the cost the ~6 hours of driving time to the store to have it “fixed” and it’s starting to get into the realms of silliness. I think my mate has been pretty relaxed about the whole thing though I’ve suggested he now cc Specialized into his emails to the bike shop and start playing hardball as they’ve still not been able to fix this issue.

Any hints or suggestions on where to from here?
 
redbruce

redbruce

Eats Squid
Try another Spesh dealer if warranty. Total Rush in Richmond have been very good with after sales support.
 
Last edited:
droctagon

droctagon

Likes Dirt
I had a similar clunk with my Enduro. In my situation it was the clutch mechanism on the derailleur.
Running a Shimano Zee 1x10. Open the clutch cover, very lightly greased spindle and friction clamp bit, adjusted the tension and problem solved.
Give it a try? Not sure what rear mech you are running, but could be the culprit.
Good luck!
 
smitho

smitho

Likes Bikes and Dirt
Try BikeNow in South Melbourne. They’re Specialized dealers so should be able to assist if warranty is still available.

I use them for the things I don’t have the tools or patience to do. They’re not super fast, but they’re friendly and helpful, plus they really know their shit.


Sent from my iPhone using Tapatalk
 
tkdbboy

tkdbboy

Likes Dirt
I recommend Astroboyracer in Collingwood. Been going to him just under two years for anything outside of my skillset.
Wealth of knowledge and meticulous in workmanship. Plus he takes the time to explain what was wrong and how he fixed it.
 
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