Brilliant Trevor I found this in the free dictionary:
strapĀ·hangĀ·er (strphngr)
n.
1. One who grips a hanging strap or similar device for support while riding as a passenger on a bus or subway.
2. One who uses public transportation.
Maybe, maybe not. I seem to recall doing a bit of "strap hanging" on the tube and also on those infernal buses you have to use when an aeroplane can't get you directly to the terminal.
I think that they call the riders in the sidecars at the TT strap hangers as well.