Bottom Bracket question

[pubrunner]

If a bottom bracket on a frame is cross-threaded, how difficult is it to get it re-tapped ? and how much would it cost ?

I don't know how they fit, but if a Hollowtech type (external) bottom bracket was fitted instead, would the cross-thread problem even need to be fixed ?

Thank you for any responses.

 

[Globalti]

They still need a good thread to screw into, the difference is that the bearings are outside the BB shell rather than inside.

Take the frame along to a good bike shop and with luck they may be able to re-chase the thread for you. I've found that opening time in the morning is a good time to go seeking favours.

 

[MartinC]

Assuming you've got the old bracket out the first thing to try is getting the threads chased out by someone (LBS) with a BB threading tool. This usually works but may leave the threads a bit loose. An external bearing BB (e.g. Hollowtech still needs the threads but they don't have to be so tight.

Ther used to be several makes of BB available that would fit a shell with stripped shells - the cups screw onto the BB casing. Don't know if you can still get them. A framebuilder should be able to put in a thread repair insert into the BB shell if all else fails.

 

[pubrunner]

Cheers for the messages fellas !!!

 

[spence]

It could be suggested the threads need to be more accurate for a HTII/X-Type BB as the bearings are independent of the axle and therefore rely on the BB shell for alignment. Mfg's recommend facing the BB shell faces prior to fitment, although I'd have thought most new(ish) frames should be OK if the surface is unpainted/undamaged.