>>1924768>>1924769Oh, another couple things about flip-flop hubs. If you're not already aware, the freewheel side is just one set of threads and the fixed side is one set of threads for the cog, and a smaller, left-hand-thread set for the lockring. But the threading for the freewheel and the threading for the fixed cog are the same (the freewheel section is just deeper). So in theory, you could thread a freewheel on the fixed side too.
The point of that would be if you have varied terrain or are doing longer rides or just want to switch it up for some reason, and you could get a larger or smaller freewheel to change your gear ratio. Keep in mind though that you need to coordinate your chain length and how much room you have to slide the wheel for/aft in the dropouts. And if you have a rear brake, the pads may not line up with the rim after you move the wheel.
I'm saying all of this assuming that the flip-flop hub is fixed/free or fixed/fixed.