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-   -   Inspecting for cracked bottom bracket shell (https://www.bikeforums.net/framebuilders/1219291-inspecting-cracked-bottom-bracket-shell.html)

mrv 12-11-20 04:11 PM

Inspecting for cracked bottom bracket shell
 
Pic below- 30 year old RockHopper
Bottom bracket shell
Question- can a crack form in the weld?
Theres some corrosion that almost looks like a failure start. Looking inside the shell, I can’t see any cracks.

Why am I asking- I’m chasing an increasingly loud creeking sound.
- cleaned the drive train.
- replaced the chain
​​​​​​- cleaned the BB threads and greased the threads and tightened.
- shifting is fine.
- replaced the pulleys but haven’t ridden that change yet.
- probably I’ll try another wheelset to see if it’s the hub - but the noise is only present when pedaling, and that’s kind of intermittent.

Anyway, I broke a 30 year old RockHopper in March- it cracked around the BB shell A friend gifted me this Frameset. So I’m predisposed to think I broke another the same way.

any suggestions are appreciated.


https://cimg4.ibsrv.net/gimg/bikefor...2948dcdae.jpeg
https://cimg5.ibsrv.net/gimg/bikefor...af29c7563.jpeg

guy153 12-11-20 05:54 PM

It looks all right to me. Does the creak go away if you ride standing up out of the saddle? The saddle itself can be a source of loud creaking in time with the pedals that makes you think it's something with the BB etc.

mrv 12-11-20 06:09 PM


Originally Posted by guy153 (Post 21828755)
It looks all right to me. Does the creak go away if you ride standing up out of the saddle? The saddle itself can be a source of loud creaking in time with the pedals that makes you think it's something with the BB etc.

Hi - once the noise stars clicking and creaking I can stand up and it stays. I've had a creaking seat rail before, so I know what you mean.
I'm hoping it's the hub, which I'll try tomorrow, if it's not too rainy.

But riding along, like applying a bit of torque into a head wind, it sure sounds like the BB is clicking and creaking.
Thanks!

..... or i'm hoping it's cracked so i can order up a new XOXO........ https://www.kickstarter.com/projects...s-xoxo-bicycle

unterhausen 12-11-20 06:33 PM

that looks uncracked to me. Unless there is some major malpractice in the weld, cracks start on the side of the seat tube.

I would certainly inspect that frame thoroughly for cracks, particularly the head tube.

But once you have lost faith in a bike, that's more than reason enough to retire it.

Andrew R Stewart 12-11-20 10:31 PM

Creaks are far more often a component thing and not a frame source. I'm with Eric on the images not showing what I would expect to see if there was a crack in the weld. I suggest a thorough servicing bod the bike including things like seat post/seat clamp and ring bolts. Andy

mrv 12-12-20 06:46 AM


Originally Posted by Andrew R Stewart (Post 21829042)
I suggest a thorough servicing bod the bike including things like seat post/seat clamp and ring bolts. Andy

Good reminder!
I’ll look at the chain ring bolts when I swap wheels to confirm the rear hub is not full of grit.

David Tollefson 12-15-20 12:07 PM

Try the rear wheel skewer as well. I had that issue on an older aluminum MTB -- I even sanded paint off some areas of the frame checking for cracks. Turned out to be the rear wheel skewer not being quite tight enough. :lol:

mrv 12-15-20 09:21 PM


Originally Posted by David Tollefson (Post 21834014)
Try the rear wheel skewer as well. I had that issue on an older aluminum MTB -- I even sanded paint off some areas of the frame checking for cracks. Turned out to be the rear wheel skewer not being quite tight enough. :lol:

I don't think it was the skewer - I had the wheel on/off several times working on the bike and cleaning it.

- I think the problem might be in the freewheel cassette body. I need to do a bit more diagnosis.
I changed a bunch of things at once, and the noise stopped: put a NEW cassette a different wheel; changed derailleur pulleys
So not sure which of those changes fixed it - but now I got no good reason to buy a new frameset. nuts.
Probably I'll stick the old wheel back on with the new cassette before I spend the $90 replacing the cassette body. Velocity - Hubs, Parts, Cassette Bodies

cheers!


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