Originally Posted by
Grand Bois
Maybe the mechanical engineer can explain how the cassette hub was converted to fixed gear. The only way I know involves welding.
Flipping the wheel over and using a 6 bolt cog in place of the Brake disc works well .
from reading this Line,
The original owner converted it to a fix gear with conversion kit using rotor mounts on Shimano XT hub.
It is my Sight unseen <Guess> that , that may be what the OP meant.
./.