NEXT time, slap your bike lock on your curbside find, and attach it to a nearby tree or traffic sign. Then you can return at your leisure and make a more reasoned determination. And even if it was a boat anchor, as BBM insinuated, you could make some money off it, if nothing else.

Aquakitty's comment could be true, though, so you want to be certain that it is trash day when picking a "complete bike, air in tires" off the curb.