I'm thinking it could be mostly a U.S. problem, since cycling isn't as popular here as it is in many other countries, but perhaps they have the same problem.
(I'm in a resturaunt)
Waitress: Wow, you look like you got some sun today.
Me: Yep, I rode 80 miles on my bike, mostly hills. Forgive the silly bike shorts tan lines.
Waitress: That'll do it. Can I get you something to drink?
Me: Yeah, I'm beat. An iced tea, and lots of water. I need to rehydrate, and could you bring some bread? I'm starving.
Waitress: Will do. What kind of bike do you have?
Me: Trek OCLV
Waitress: I've never heard of that, but my brother has a Harley.
Me: That's not a bike, it's a motorcycle. Bikes have pedals.
Waitress: Oh.... OH!
Uh, why would I be tired and starving if I'd just ridden 80 miles on something with a motor?? Plus, how many motorcycle riders get "bike shorts tan lines"? How many times have you had someone assume that bike meant motorcycle? For me it's almost every time, unless of course they know me.