I think there is a thriving business of vintage car rentals, especially for more secondary roles (drive-bys). But, I could understand how bicycles could be considered props, then just discarded.

I think it might be fun to participate in a film or movie. As [MENTION=280039]Lascauxcaveman[/MENTION] mentioned, however, I'd ask for an actual role. If they want my bike, then they had better take me with it. Although, perhaps they'd be casting young racers, and not want an over the hill bike commuter. Nonetheless, there could be roles of trainer or something. But, of course, you have children that might be interested too.

I think I'd be more incensed by an offer to buy my bike than to borrow or rent (although "borrow" sounds awfully low budget). I.E. Deeming me unworthy of owning a classic or vintage, or nice bike, without even taking the time to get to know me.