Originally Posted by
RChung
Modern Flip-Flop hubs are fixed gear on one side and ratcheting on the other, but they're the same number of teeth so you don't have to change the length of the chain. To change the gear those riders would have had to have had either another front chain ring or else a lever or idler to change the chain length.
Nope. Horizontal dropouts allow a couple-tooth difference in cogs without needing multiple chainrings or modifying the chain length.