Just before I attack it. The non-drive is a LH thread I assume and so does the lock ring undo the ‘wrong’ way too? ie turn to the right to undo?

Thanks

There are two left hand (reverse) threads on a bike

The left hand pedal
BUT the right hand BB thread!

Does that answer the question?

….unless its an Italian thread BB that is. But it’s probably not. 🙂

Won’t be Italian. So the non-drive is a normal RH thread and therefore the lock ring unscrews normally? Lefty loosy?
So the action of the cracks turning may loosen the cup? Or it doesn’t because of that trepination effect of ball bearings?

Thanks

So the action of the cracks turning may loosen the cup?

No. There’s some bizarre mechanical reason it’s the way it is, but it’ll tighten the cup if anything. I can’t explain why but its DA TRUUF! 🙂

I think that’s the ball bearing thing – must check on Sheldon!

To my mind, with the preload cap set up, HTII is crying out for a cup and cone bottom bracket. Imagine the size of the balls.

because of that trepination effect of ball bearings?

Is that where the ball bearings make a small hole in your skull?

IGMC

So the action of the cracks turning may loosen the cup? Or it doesn’t because of that trepination effect of ball bearings?

It’s because, while the cranks might be turning anticlockwise (looking from the left), the bearings which actually touch the cup are rotating clockwise – hence tightening the cup into the frame.

Hole in skull is trephination I think, using a trephine. 😉

I would put a hole in my skull with trepidation.

Think of the axle as a geared wheel and the bearings as another and the cup as another. Then makes perfect sense why it’s that way around.

‘trepination’! Every day’s a school day. 🙂