I have a summer bike...I need a back-up for it when I'm over-hauling it.

I have a winter bike...I need a back up for that one. In case I have a problem with it, I don't want to ride a summer bike in the winter.

I have a rain/snow bike...I need a back up for that one. Can't ride dry weather bikes in the rain.

I have a Saturday "cruiser". Look, I don't need a back-up for that one. Aren't you happy.

Oh, the five extra frames? Just in case I bent or crack the frame on one of the "working" bikes.