Originally Posted by
rpenmanparker
On common Taiwanese hubs with sealed cartridge bearings only a 5 mm Allen wrench is needed. It is really incredibly easy. Since the over-locknut dimension doesn't change or the center of the hub move, redishing isn't necessary. If your hubs are anything like this, you should have no trouble. You can easily check them out before ordering the parts.
That's not entirely correct.
Since the 10/11 SPD freehub is 1.85mm longer than the 8/9/10spd freehub the worst case scenario impacts both OLD and center to flange dimensions by just that much.
What many brands have chosen to do is a combination of machining of DS flanges and accepting the OLD as 131mm in an effort to have as little impact on existing hub dimensions as possible.
Another issue then becomes about chain line. Simply swapping freehubs will result in this being off somewhere around 1mm - 1.85mm or so. This can create clattery drivetrains and impact shifting performance at the extreme end of the freehub.
Another concern is how deeply the grooves on the 10/11 SPD freehubs travel down to the base of the freehub vs on the 8/9/10 SPD versions. This can place the largest cog too close to the spokes and can either make the chain rub on the spokes or, much worse, can result in the rear der getting caught in the spokes, spun around and ripped off the bike trashing the hanger, the dérailleur and maybe even the wheel itself.
There are plenty of dealers or resellers who will tell you that all you need to do is swap freehub bodies but this is not always the case. I strongly suggest you contact the manufacturer and get specific instructions on what is and isn't possible.