So I was going along on Friday and my NDS crank falls off. I realised I put too many spacers on the NDS so I assume the crank wasn’t properly engaged. So I took the spacers off and installed the cranks again and all going good on tonights ride but the same thing happened.

What’s causing this?

Which cranks do you have?

Hollowtech 2

I’m going to guess SLX.

Yes

I have a KCNC BB with hollowtech and all is fine here, onlyz thing that has fallen off it is me.

On the NDS on an SLX there is a little thin spacer on the end of the cranks , that goes in the gap with the 2 crank bolts.
It has a small pin in it that fits in a hole on the axle. The pin gets damaged, and this makes it easier for the NDS crank to come loose.

Missing end cap?

[/url] Untitled by danthomassw13, on Flickr[/img]

Looks like item 9 on this diagram

Seem to have got that. The splines on the NDS crank seems to have gone smooth half way through if that makes sense.

Check the pin on the black spacer. It’s pretty fragile and can come loose. The pin has to be located in the axle hole.

It may be that having come loose twice, the crank splines have now worn too. If so, at least a new crank arm, which will cost almost as much as new cranks 🙁

Yeah i’ve ordered new cranks and hopefully have no more problems

I don’t think I have number 10 either.