just wondering can I fit x7 jockey wheels on a x9 rear mech because I am a misserable B ???

Yes. I do this as I too am tight or as I prefer to say, not stupid.

Cheers thought they might fit but wasnt to sure thanks.

Good news, my X9 jockys are now looking like Chinese throwing stars.

Actually, if your looking to fit new ones, can I ask why ?

I didnt think it really mattered how worn they got – so long as they guide the chain they do their job. So I reckon the teeth can completely wear off, they will still “work”.

I was going to let mine continue to wear out till they actually stopped working – which I imagined would be when the plastic had gone and I was down to the spindle.

I’ve just replaced mine, not due to tooth wear, but beacause they’d worn the centre bore that much that they were rocking about on the spindle and causing up shifts in particular to be very vague experiences.

I didnt think it really mattered how worn they got – so long as they guide the chain they do their job. So I reckon the teeth can completely wear off, they will still “work”.

A few weeks ago I serviced a 40-50 year old tourer that had just rotating discs in there to guide the chain. Worked absolutely fine.