[ryansuske]

I have a stumpjumper comp from 2003 that I would like to keep as my winter bike, but it has damage on the drive side threads of the bottom bracket. It is a English (BSA) threaded bottom bracket and the guys at the LBS were thinking about boring it out to Italian threads. Has anyone on this forum tried something like this before? What was the result?

Thanks

Ryan

 

[lightjunction]

Depending on how bad it is, you could try to chase the threads with a cutting tool to smooth them out again. The interface between the bottom bracket and the frame won't be as tight any more, so I'd recommend using a medium to strong grade loctite to prevent it from moving around or stripping the threads further.

I've never heard of someone changing a frame from British to Italian BB, but that doesn't mean it wouldn't work. The Italian diameter is a mm or two larger than the British, and the shell width is 70mm as opposed to 68 or 73mm like the British one, so it might be close enough to work. Tough to know which one to recommend without actually seeing the bike, but I'd keep the Italian bb conversion on the back burner as a last resort.

 

[mtnbiker72]

I would not convert a English BB to Italian. The drive side threads go in the opposite direction and it will really limit your BB choices. You should be able to chase the threads with the proper tool no problem. I spent 8 years working on bikes and the only BB's we converted were French to Italian. I never came across a BB that couldn't be repaired using a thread chasing tool.

 

[pcmark]

Do you have any pics of the threads? Unless it's totally wasted I'd imagine it's fixable by chasing the threads. There are palces that can repair your frame by epoxying in a threaded insert, but I don't know what they charge.

 

[ryansuske]

My LBS converted it to italian threads and I am using a Shimano 105 bottom bracket now. It works perfectly since the inner diameter of the bearings are the same as the XTR hollowtech bearings. I have done several rides and about 150 miles and it works like new.