Originally Posted by TejanoTrackie

The only reason a single freewheel body has more threads than a fixed cog is that the body is by necessity wider to accommodate the bearings and pawls, not because all those extra threads are needed. Since hubs were originally threaded to accept multi-speed freewheels, they were made wider as well. Considering the fact that track racers, particularly sprinters, tend to put out more power than road racers, yet don't strip the threads on fixed cogs and hubs proves that a fixed hub can adequately handle any load placed on a freewheel.