SD Fixed

The bottom brackette on my Bianchi has become ovaled out. That is to say, rather than being round, it's now somewhat oval. This cause the cups to loosen up over time. The frame isn't one of the expensive ones, but it's got soul. I'm wondering if there is a method of repair (perhaps by a frame builder) that wouldn't call for replacing the whole brakette. Anyone know?

tommy2pants

I don't think I have ever heard of such a thing. If it is Italian thread, the drive side tends to be self loosening and has to be installed extra tight. If the BB is somewhat buggered,loctiting the cups in is one possible solution. If it's English thread, a framebuilder could rethread it to the lager Italian thread.

SipperPhoto

I'm not sure.. but it may be possible to have a new bottom bracket welded on... Maybe check with Brian Baylis in La Mesa... he just installed a new dropout on my LeMond... and the work is great...

is it a lugged frame ? probably easier (I would think) if it was lugged... could be wrong though.. I'm no welder

Jeff

lotek 

William,

I agree with Jeff, Talk to Brian Baylis, worst case he
would remove the current BB and install a new one.
His work is first class (better?), he is very into old
Masi (he worked at masi california) and track bikes.
if you need phone number/e-mail PM me.

Marty

SipperPhoto

His work is great... he did take a long time to get it done... but it was worth it... super clean :-)

Jeff

F1_Fan

I'd be pretty confident betting a large sum of $$ that this is impossible. There's likely another reason for the problem.

SD Fixed

While I disagree with you, based upon my first hand observation of the problem, I'd like to hear what your view of the problem is.

tommy2pants

It isn't worth arguing about. Unless it is a collector piece, or something very specisal, putting a new BB in and repainting just isn't cost effective.I gave you the other options.

SD Fixed

Tommy, that post was for the "F1 fan guy", not you. Please re read the post and you'll see that. I was pointed to Mr. Sheldon Brown's website about problems on Italian BB loosening up. I've put some pretty strong torque on it, and I do have the special purple loctite (not the blue version) that's akin to super glue, though I've not used it. I'm not here for cost effective, however, I was looking for solutions that my not cost much. Thank you for that perspective.

If I had a web page to post pictures from my higher resolution camera, you could well see it.

When threaded down with out the lock ring: I am able to cause the cup itself move in different directions: it should be stable. In the seat post down position, this happens at approx 2 oclock, and 7 oclock. If I have a crank on one side, it's more readily seen.

dafydd

If it's steel, maybe peen it round again; crude but sometimes effective. A mavic bb might work (?!), but probably cheap to have it tapped if english threaded (assuming it's not ovalized beyond 36mm).

Rev.Chuck

The cheapest fix is to thouroughly clean the threads in the shell and on the cup, then use a liberal amount of red loctite and install the cup. This works best if it is the fixed cup as once red loctite cures you have to heat it to break the part loose.
Another cheap fix if it is the adjustable side is to use JBweld. Once again clean everything, then very lightly oil the threads of the cup, smear JBweld into the shell threads and screw the cup all the way in. Then remove the excess from the other side of the shell. Let it cure and the cup should (Hopefully) screw out. It is a little risky as the cup could get stuck if the threads are not well oiled. I have never done this for a BB but I have used it on some thread repairs where the torque was not real high.

F1_Fan

Well, a relatively thick steel tube supported by two screw-in caps is pretty unlikely to ovalize (even just a single cap...) under the forces generated by an average person. I saw some incredible cases of bicycle wear and abuse back in my LBS days and I don't remember such a problem... even on hi-ten steel bikes.

Without seeing the bike I'd guess that you had a loose BB cup and while riding like that you wore the BB shell threads in a spot that corresponds to your power stroke. The shell would still be round but the threads would have some slop in them at two locations.

I agree with the Loctite advice. Essentially, glue the cup in and hope for the best. Otherwise replace the frame if the repair cost for a new BBshell is excessive (I'd estimate at the lowest $75-100).

SD Fixed

I think we're arguing about the same thing.. just a matter of where something ovaled out.

We put an insert in it last night, a shimano one for italian threads. It took some doing because the threads were shot in two spots (as you've stated).. and with that the BB was bent in one spot as well. Seems to be holding.