what is this bike? my dad would like to get one (as his dad had one) his dad can't remember what it was (model and year) my grandad came to australia in 1949, so it would be from around then. i've looked online, but the ones i see seem to always have this "tube" looking part at the rear wheel. so does anyone know what the model and year of this BSA are? any ideas? places to look? cheers.