[leon2982]

My PowerTap SL freehub body gets knicked real easy and I even had a cog slip a little. Any advice on how to avoid this and prolong the life of the freehub body?

 

[rockcrusher]

use a cassette that mounts the cogs on an armature like the dura-ace or sram red. The aluminum body will spread out the load of the larger cogs across the whole armature, the smaller cogs don't get enough force to need to be put on the armature (except in the Sram Red's case I think).

Cassettes with individual cogs like 105 level and some older ultegra ones will dig in because each cog can move independently of the others under load. Surface area is your friend here.

 

[ericm979]

If you are using Dura-Ace or Ultegra cassettes only the last three cogs are ganged. You can use American Classic "Cassette Clips" to keep the solo middle cogs from digging into the freehub body.