ok, so i need a new cassette, and this time i want one that isn’t going to ruin the freehub.

There is a 5700 12-27 on there at the moment which has deeper splines but some cogs have some splines missing. These cogs have dug in much more.

Which cassettes don’t have this missing spline thing going on? Tiagra 10 speed seems “normal”. Are SRAM any better?

Ultegra level cassettes have the top however many sprockets on a broad alloy carrier ala XT, and this has saved my alloy freehubs.

generally the more expensive cassettes use an alu carrier for the larger cogs that spreads the load & prevents damage to soft alu freehub bodies

The higher end ones don’t seem to have any more on the carrier and have the same problem… cog number 9,7,6 on here have teeth missing…
http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/CS/EV-CS-5700-3016_v1_m56577569830703168.pdf