Parden the funny mental picture of Knotted out on a ride and SCREAMING LOUD pants with HALLUCINOGENIC psycho flowers and/or Zoic capris in her size go by "wait! those are my pants! If I can't get in those pants can I at least buy you a drink?"

As for the being called sir part I think sometimes people see what they expect to see.

Tall person in a bike shop = gotta be a guy
Passing a guy on a bike = gotta be a guy
Handy with a pedal wrench = gotta be a guy

and then they look and "oops".