Originally Posted by
Tim_Iowa
Also, due to the oversized axle, these Shimano MTB hubs also require a new/different freehub. This freehub can't be removed with the previously-standard 10 mm hex; a 14 mm hex is required (and hard to find).
My Deore XT FH-T780 rear hub is designed thusly. Besides being delivered with a bad freehub (which was then replaced by seller), my hub has been reliable and smooth for ~1500 miles.
I don't know where the demarcation is between oversize or standard axle size in the current Shimano lineup.
Yes I've heard of a lot of freehub issues with the M770, T780, etc, which is worrying since I just bought a T780 myself for a new wheelbuild. Starting to wonder if I should go more old school myself. I think the T610 has the classic bearing and freehub design, but IIRC the T780 has slightly more symmetrical flange spacing.