WW2 1942 BSA Airborne folding bicycle, 1st Pattern. The vast majority of the 70,000 Airborne bicycles are of the later model with a single seat tube. This bicycle is the first lightweight version with a double seat tube, bearing frame number R 384. Very few of these were produced in a great hurry according to strict weight specifications. As a result, you could actually say that this is the prototype. This led to a sturdier successor with a single seat tube—heavier and more robust. This bicycle still has its original paint finish.