Polo Bikes

I think the front wheel is generally where the action is.. spokes or wheel covers can rub off someone's leg with not much problems, but if you got the teeth of a fixed sprocket rolling around and making contact, the potential for slashings is increased.

And yes its a gimmick, which doesnt make much sense IMHO. You mess up your back wheel, you put your spare back wheel from your front forks in its place - you still need a(nother) front wheel to cycle the bike.

Actually you need another rear wheel to cycle the bike because your forks are spaced such that noone elses front wheel will work.