I’m struggling to fit a Shimano threaded bottom to my Ritchey. It’a English thread (68mm) and the RH cup won’t thread in. The new LH cup threads in nicely by hand, but the RH cup threads in about < 1/2 turn and stops. I’ve cleaned the threads inside the BB and the old RH GXP cup threads in just perfectly, no drama. I was thinking that the new RH cup could be faulty, but i’ve borrowed another new Shimano BB and that does the same. totallyconfused.com
Cheers, B

if you’re absolutely 100% sure it’s in straight then go ahead and use the tool to wind it in. You’ll probably find that it’s tight then goes loose and all the way in. If it helps put a metal bar on the end of the BB spanner and get some leverage on there.
Either that of pop it down it down to the local LBS.

They usually have some threadlock factory fitted.Give it some beans.Steel frame/ali cup….the frame will win.
Failing that I’ve got a proper BB tap set to chase out the BB you can borrow.

Has the new bb got locktight on the threads? It might be going tight when the locktight hits the threads on the frame.

Thanks everyone

RH cup is the one that threads in backwards?

Erm don’t wish to insult your intelligence but…you threading it in the right way?

Double check that you’re threading it in the right way; if you are do be careful about forcing it. Bottom bracket threads are very fine and absurdly easy to cross (it usually takes me a few attempts to get one in straight).

You really should be able to thread it in most of the way by hand.

You could have deformed threads or some swarf getting in the way in which case getting the shell faced and chased should help.

Well, if one’s in, and an old cup goes easy enough, it’s unlikely to be a case of threading it the wrong way.

If it only goes in 1/2 a turn before stopping, I’d be careful about too much force because you’ve got hardly any thread engaged and you might damage one or the other. That sounds more like you’ve not got it started straight, I’d try again starting it by hand. Unless the thread lock compound goes right upto the end of the cup threads, it should go in at least a couple of full turns before you need to get the spanner on it.

No way would I be resorting to an extension bar to put a new one in!