mamut

i dont know how this happened but the thread is stripped on the BB in the frame. is there a fix to this? threadless BB? how can a stripped thread be fixed on the frame?

davidad

https://www.biketoolsetc.com/index.cg...r-Spindle&q=&s=

mamut

thank you

ultraman6970

U can rethread the BB anyways. If the BB was english u can go to italian threading. If the frame is aluminum u can use the ALuminum magic rod and rethread the BB also.

cnnrmccloskey

https://www.velo-orange.com/grcruthbobr.html
Velo-Orange makes one too.

Kimmo 

What's the deal with that?

I have a nice ally frame with a stripped BB...

ultraman6970

There is an aluminum rod that i cant remember the name right now, u can heat it with a basic mapp torch kit... Once is hot is like applying electrical soldering stuff... so heat the area the stuff will melt, cover the threads and then rethread again. done. since is nothing structural is not a problem to use it. The problem comes when somebody wants to use this to fix a broken frame, it will work but the frame will brake in another place because there is a heat treatment that needs to be done to the whole frame after the welding.

Here it goes... https://www.durafix.com/

achoo

The bottom bracket threads aren't structural?

Of course they are.

All those thread do is hold the crankset while you're hammering away on the pedals. They're taking a LOT of stress when they're doing that.

ultraman6970

Yes i understand what you say, but i believe u are taking what im saying literally and you don't see what i'm saying yet. Besides arent the threads the ones that are taking all the stress but the whole shell. U are repairing the threads to get the BB into the shell. The shell wont have any problem after is rethreaded using the durafix rod.

But if you have the bad idea of reparing an old aluminum frame that got a problem (crack) in a welding for example in the joint of the TT and the Head tube, the durafix will work and will get the thing repaired pretty good, so good that the frame will crack in another place because the new welding is stronger than any welding in the frame. Durafix works awesome to repair threads in bikes. But not for repairing cracks.

There is a guy with a marin frame with that problem right now, look at the thread, I didnt even mention the product because will be a waste, aluminum frame with a nasty crack.

U can repair aluminum frames pretty easily and at home with this product, but if you dont have where to apply the heat treatment to the frames after wards the fix will be a waste because the frame will brake again warrantied probably next to the repair.

JohnDThompson 

Yup. And even the heat from the MAPP gas torch will compromise the frame's heat treatment and strength in that area. The bottom bracket is the most complex joint on the frame -- four tubes come together there. Compromising the heat treatment in that area is not something I'd advise.

ultraman6970

Cant remember who have done it here in the forums with aluminum. We have done it with steel anyways. The temperature is not even that extreme, the rod melts too fast to damage anything else at all. But well

fuzz2050

Sweet at that 'magic rod' is, no need to risk it when a $20 bottom bracket will do the job just as well.

ultraman6970

Well if you have outboard cranksets and one expensive frame with a problem, i doubt a 20 dols bb will do at all. Thats the reason maybe kimmo asked also.