bigalgeorge

BC-73 thread same as BB73 thread? I am replacing BB73 68mm 116mm
I ask suppliers in Asia, and they dont know. The BC has same turns on thread and other specs but SheldonBrown gives no information on BC types and doesnt have BB73 either.

Thanks for answers. Al.

davidad

VP-BC73 - VP Components

bigalgeorge

Yes, I am aware of that but I am not aware if the thread is different or not hence OP

davidad

The odds are that the threads are English because of the 68mm width.

Wilfred Laurier

Before all the terrible press-fit BB concepts came along, there were three common BB sizes - English threaded 68mm, English threaded 73mm, and Italian.

The threads on 68mm and 73mm are the same, but you generally need different cups for each size because the BB willnot be centred or properly fastened in place if you use the wrong one. Threaded BBs come in both these sizes to match whatever your frame wants.

Italian threaded BB shells are 70mm wide, and the threads are completely different - in size and even in handedness on the drive side (English is LH thread on the drive side and RH thred on the ND side, Italian is RH thread on both sides.)

However, I don't think any of this matters. I think the BB73 the OP is referring to is just a model name for a particular bottom bracket, as BC73 is in the above link. If you have a 68mm wide threaded BB shell on a modern-ish bike (after ~1980), the bike will work with standard Shimano 68mm bottom brackets. You only need to match the spindle length to get the right one.

Iride01 

Why do you say your's is a BB73 then go on to identify it as a 68x116 size?

Don't be so secretive about your bike. Let us know what it is and maybe we won't be so confused about how to answer you.

bigalgeorge

Its no secret, this forum rules are: You are not allowed to post URLs or IMAGES until you have at least 10 posts
I have likely done this, but still cant post you a picture but anyway, and asking the mediators of forum has given no joy either.

The bike is one of a bunch of Ebikes I got made in China. It came with a graunchy BB.
Pity the picture thing doesnt work as you would see the problem, but after taking out my trusty calipers I figured that China must have had a bad day, because the axle in all my spares BB were the wrong way around. Just 1mm more on axle width one side, but enough to stop the slip-on hall-effect sensor from going on.

Thanks for info regards threads Ive order a VP BB and hopefully it will sort it out.

Maybe one day I will be able to post pictures here but not holding my breath.
Al