I was having a spot of bother with centring the rear brake on my good old Boardman Hybrid. I’ve treated it to some super duper shiny Carbon rims, which are made by Mavic, and feature a new design of rear hub / freehub. This is a good thing ( because it’s very clever) but a bad thing, in that I’d never heard of it, and didn’t know how it worked. Basically you can modify it to fit everything from 135mm to super boost, with changeable collars. I didn’t know that to start with. Once I’d worked out what I had ( 142 mm thru axle as standard ) I bought the 135mm collar, and some 12-15mm to thru axle to QR adaptors. So far so good. However, the rear brake was just shy of where it needed to be to not rub on the right hand pad. So I tried the trick with a folded card over the disc to try and give it the gap it needed. Nope, still rubbing slightly. So I had a close look at the hub, on the non drive side was a little plastic collar
I gripped it in a pair of pliers and bingo, it popped off.
I put the wheel back in, and the calliper then centred perfectly. The bike is much lighter and more responsive now, and I’m using tubeless tyres ( which actually work on this sort of application ). Every day’s a school day with these new Mavic hubs as well.