I am going to upgrade my rear mech to XT, but i now realise there are two types, XT, and XT rapid rise, what is the difference?

Rapid Rise (aka Low Normal) is sprung the other way, so if you press the thumb lever it shifts to smaller sprockets. It'll do your head in, get the normal sort ;-)

Yep, definitely agree with Mike. Standard rise ones are cheaper too.

Thanks alot. i think i will get the standard rise

Also, would you opt for long cage or short cage?

If you've got three chainrings then long cage is almost certainly the one for you. If your brain works properly then rapid rise is also worth considering, you'll have to get used to it sooner or later, unless you go the SRAM route.

Long or short is more down to the cassette than the number of rings. But yes, long for most wide-range MTB setups.

And I expect regular rear mechs to be available from Shimano for many years to come. No need to get used to it yet. Although I have ;-)

On a mountain bike the chainrings are almost always the deciding factor, the cassette very rarely comes into the equation.

Long and short cage Shimano mechs both have a stated chainring difference of 22T. Doesn't matter if it's 22-32-44 or 26-36-48. The critical thing is the capacity, which is the total difference at both ends. Since the difference between top and bottom on an 11-34 is 23, the difference on, say, a 12-28 is 16, and the difference at the front is 20 or 22 on all standard setups, it's clear that the cassette is the more important factor. And the actual number of rings is completely irrelevant.

But you're right, he'll want a long one ;-)

Thanks alot, ive just placed my order, XT standard, long cage, £34.99, better price than i thought it would be.