Having fixed my bike so many times over the years, I can easily sketch a correct bike - if not in terms of proportions (at least without any corrections), but in how the frame is constructed and how all the moving parts come together. I guess someone who doesn't need this knowledge will just use a more abstract model.
I, too, can correctly draw a bike. I think anyone who's spent any time fixing bikes will be able to do this; if you know that it's called a "diamond framed bike", and you know why it's called that, it'd be pretty hard to not know how to draw it.
