Loctite 222 and Italian bottom brackets.

On a hill climb the other day this fabulous non-feature came to the fore and my drive side cup unscrewed itself. Luckily the frame didn't die, the only clue was not being able to get the thing onto the big ring. Then the dreaded sight of exposed thread due to precession.

For anyone that doesn't know - Italian frames bb cups are both right handed threads unlike the English chaps who sat around a table and said what about precession, due to the bearings rotating the opposite way to the forward rotation of the crank on the drive side? Came up with a left handed thread, then went off and had a pint mug of tea, and tried not to think about Sophia Loren.

So anyhoo. I have two Italian bikes, so how much threadlock would I need. Do I do both left and right cups, and would white spirit or citrus degreaser be enough to clean the threads out? I could just have the bike shop gorilla the BB in with a torque wrench, but I think campag alloy splines are a bit crap.

I did not know this.

I have an Italian 1980s steel frame.

I welcome the fiery gates of death.

Pretend to be Klingon, clench your fist to your heart and boldly declare "today is a good day to die" before sitting astride...

Yeah it seems like thread lock is a good solution. Not only will it help resist precession by adding friction, it will help waterproof your BB shell from the sides. I've always used 243 in the workshop and I trust it. A blob about the size of a pea is fine for 1 BB cup. Thread it in before it dries. No need to do the non-drive-side cup because mechanical precession dictates that forward axel rotation will tighten it.

Also, yes any degreaser is fine. An aerosol can will help blast the grit out. Make sure you clean the degreaser away and let it evaporate off for a bit before you apply grease.

Despite admittedly poor design, it's worth noting that not all Italian (and some French) bikes try to kill their riders in this way. I wonder whether your BB bearings were dry, creating increased friction on the inside of the drive-side cup, and worsening the unthreading issue.

Hope that helps.

thread lock...before you apply grease...

Do these things mix?

Meant to ask that too... 😊

Right - glad you pulled me up on that. No, mixing grease with wet thread lock will reduce the efficacy of the thread lock and is therefore a bad idea. In the case of your bottom bracket cup threads, however, I am advocating the controversial position of not applying grease.

Why? Primarily because it allows you to thread in the cup while the thread lock is wet, maximising it's dispersal and providing the best chance of solving your problem. But won't the cup corrode in the frame? Probably not, because I assume (from the threading) that both the cup and BB shell are steel, which eliminates the chance of electrolysis. So you're just left with good old fashioned rust, which develops slowly and if you take care of your bike, you can manage.

If you do want to grease your cup threads, then you can always apply the thread lock, let it dry, then grease the shell and cup and thread it in. The slight downside of this technique is that you might see strings of thread lock coming off as you insert the cup.

Hope that's helpful.

If you do want to grease your cup threads, then you can always apply the thread lock, let it dry, then grease the shell and cup and thread it in.

lolwut