it all depends. I have 4 bikes but all different uses, road, MTN, track, commuter. I don't think I'd ever have more than 2 of the same type bike, i.e. 2 road bikes is useless to me, I can only race one of them, I have other bikes for bad weather etc. 2 MTN bikes, useless unless say one is a SS, and one is geared or FS or something like that.