Originally Posted by number6
Forgot one thing to mention, the rear cluster did not freewheel but did have a clutch of sorts that would allow the cassette to move in case of mechanical disaster.
Good point. That was the Friction Freewheel, which was only used with the FFS. Most people familiar with the FFS think they are fixed cogs, but like you say, they will freewheel. They were designed so that the force requiring them to freewheel was higher than that of the crankset freewheel, forcing the crankset to freewheel during normal coasting conditions. If something abnormal happened, like the chain becoming derailed and caught between the chainwheel and chainstay, then the resistance would cause the rear cogs to freewheel. Many people that stumble across them erroneously think that they have a siezed freewheel.