stirring it up re. bikes

[Colm Donoghue]

following on from the folding bikes thread:

Whats the largest amount of "bike" you could bring on a train and it not be a bike?

I'm thinking gear cogs is fine, full bike is not ok.
a front wheel would be ok, how about a brand new clean frame?
where would you draw the line?

prize* for the funniest answer (unless I'm drinking and laugh and spray all over the monitor)