I have a voodoo bokor and I recently swapped the back wheel, from a formula hub to a shimano XT, but there is a bigger gap between the (IS) brake mount and the rotor… the front has the usual 2mm gap but the back now has about 5mm on the inner bolt and about 8mm on the outer??

do I need a different adaptor and if so which one ?

Got a picture?

Sounds like something’s not in right.

Check:

Dropouts on the correct part of the axle?
Are both dropouts lined up – i.e. the wheel’s in straight? (they adjust for SS use)
It’s the right sort of XT hub, not a different spacing/tandem variant.

(I have a voodoo bokor 29er, the brake mount’s pretty standard)

Sorted it, spacer in the wrong position in the hub, cheers 🙂