So, I've been wondering. We all know that older roadies used to use fixed gear for their winter training, and that this was generally on their main bike, rather than a specific training bike. I also know that up to the 70's, it was common for bikes to come with flip-flop rear hubs, with a regular side threaded for freewheel, and the other side threaded a track cog, with the reverse threading for a lockring. So, I'm wondering, did riders have two wheelsets, or is there some black magic way of building up a wheelset so that you can have a 5 speed freewheel one side, and a track cog the other, and have the chainline sufficiently sensible to use? I know it can be done with a single speed freewheel and a track cog, because the chainline can be the same both sides, and I'm fairly sure that the answer here is "no chance", but maybe someoen knows?