I had one of those myself, still do, actually, though it has been
retired to a life of ease in my spare parts box. And being one to remove
the cogset regularly for cleaning, I noticed the same thing happening.
Being a tourist/recreational rider, I don't put much strain on my gears
either.

The problem is as you state. The cogset was held to the hub by the
pressure between the bearings. If they are adjusted correctly, there
should be NO play, as this would cause the interface between the splines
to wear. Which, after 50,000 miles or so, mine had. Though not to the
extent you describe (about 50% of the aluminum spline still remains on
the hub).

This was also the reason for the design change, which is actually a
modification. The hub/cogset interface is basically unchanged, both
parts still have a very similar spline, but now they are held together
tightly by a 10mm bolt, which prevents any movement between the cogset
and the hub.

The swelling in the hub allows for the 10mm threading for this bolt.

- -
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Your Friendly Neighborhood Wheelman

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