Question about freewheels, cogs and flip flop hubs

[laura*]

Isn't the freewheel aspect pretty much covered by the flip-flop hub itself? I kind of assumed it was built in.

If the hub was like a modern freehub, then yes the freewheel aspect would be built in. However, that's not the case.

Both sides of the flip flop hub accept thread-on parts - the fixed gear and reverse threaded lock ring on one side, and a freewheel on the other.

These days, there isn't much choice when it comes to single speed freewheels. You probably have to take whatever brand your LBS has. Be aware that there are at least two thread standards: the regular one, and a smaller one that is generally for BMX bikes.

I just looked at a QBP (major bike parts distributor) catalog. You have three brands to choose from: ACS, Dicta, and Shimano. With ACS and Shimano, you have a choice of a brown finish or a chromed finish, and of compatibility with single speed or multi speed chains. Dicta's come in brown and use 3/32" multi speed chain.