Specifications changed without notice

For the x60 generation of cassettes, Shimano cut the notches for the final gear shallower and terminate the cut at a right angle instead of beveling them. This can be observed in the picture above. Note that the notches are cut deeper, and the terminations are beveled, in the x50 series gear on the right.

The change do not affect users of Shimano rear hubs. However, other hub (DT, Chris King, Ringlè) users quickly discover that their cassettes remain loose no matter how much they torque down the lock ring.

The remedies are:

1.) Purchase either a 0.5mm spacer from Chris King or a 0.3mm (preferable) spacer from Wheels Manufacturing, Inc. The spacer will go on first, and then the cassette is installed. You will know if the spacer is too thick: the chain will rub on the seat stays in the smallest gear no matter how much you adjust your derailleur.

2.) Fabricate a spacer with tin snips from a soft drink can.

3.) Substitute the gear with one from the previous generation. I.e. a x50 series cassette.

4.) Very carefully file down the splines on the freehub. If you have nerves of steel, you may use a dremel. Of course, it goes without saying that this option is only viable if the freehub body is made of aluminum.

It is worth nothing that some riders who chose option 1) or 2) obtained a Chris King cassette lock ring. The Chris King lock ring has more threads of engagement than Shimano's. Sometimes the spacer can reduce the threads of engagement so much that the lock ring will strip before the specified torque (40 Nm) is achieved.

I used a combination of 3) and 4) for my Ringlé rear hub.