Bottom Bracket Threads Worn

[twentysix by twentyfive]

I have a much used and loved frame. 531 Reynolds tubing. But the Bottom Bracket threads are so worn now that sealed units just won't stay tightened at all. So would this
http://www.sjscycles.co.uk/product-...LESS-for-frames-with-damaged-threads-4521.htm
be of any use? What do you think? How do they work/stay tight?

 

[PpPete]

I have a much used and loved frame. 531 Reynolds tubing. But the Bottom Bracket threads are so worn now that sealed units just won't stay tightened at all. So would this
http://www.sjscycles...hreads-4521.htm
be of any use? What do you think? How do they work/stay tight?

You'd need to get the remains of the old threads reamed out. I think those are a press fit, so it's a professional job.

 

[Deleted member 1258]

It looks like the cups are screwed onto the cartridge instead of the BB and tighten against the BB. I have no experience of them but they look a good solution to the worn/damaged BB problem.Theres a simular one towards the bottom of this page. http://www.velosolo.co.uk/shopchain.html

 

[accountantpete]

Have you tried Threadlock or ptfe tape?

 

[alecstilleyedye]

make sure it is compatible with your cranks. if you're at all unsure, check with a bike shop. apologies if i'm teaching a granny to suck eggs…

 

[Alien8]

I used a similar Acor threadless bottom bracket when I managed to strip the threads on an old frame some time ago - it worked okay.

Both ends of the BB should be tapered so tightening it up holds it in place.

For a good fit you might also need to file a bit of a taper on the inside of the shell - but don't overdo it or it won't fit tight.


You'll also need two BB tools - to hold one side still whilst you tighten the other.

I also used thread-lock to keep it in place.

 

[MartinC]

Alien8's post is the correct info. This is a threadless BB. It doesn't require threads in the BB shell - the 'cups' screw on to the BB body so that you can fit it even if the threads in the frame are useless. There's normally a small taper where they butt up against the frame to ensure a tight fit so filing a small corresponding taper on the frame is a good idea. You don't need to get the frame reamed. It's also possible that if the thread aren't too bad that a BB threading tool will cut enough new thread for a normal BB to work - a good LBS can check this for you.

There are 2 standards for tapers on square taper BB's - ISO (Campag, Miche and some Stronglight) and JIS (far more common). They are slightly different and using one that doesn't match your cranks may cause a problem. A bracket width of 70mm suggests that it's intended for Italian BB shells (i.e. not 68mm which is the BSA standard). It's more likely (but by no means probable) that if it's intended for an Italian BB shell then it's ISO tapers. You need to check the Chainset you intend to use it with and with SJS to find out if it matches.

 

[twentysix by twentyfive]

Ah - that's brilliant chaps. Thanks. Sounds like the threadless BB will be the way to go as I have tried the ptfe tape and all the rest. Frame is 30+ years old and there just isn't enough thread anymore. C'est la vie..........