Vintage Road Racing Association

Interesting to look at the frame detail and compare to Paul's design. Very similar.

http://www.ebay.co.uk/itm/Classic-GP-Sidecar-Chassis-/200719740134?pt=UK_Motorcycle_Parts&hash=item2ebbd42ce6#ht_500wt_1413

The double loop (Norton style frame) was and still is generic, you may learn to leave enough room to remove the spark plugs etc, add gussets where the most stress breaks the joint, or simply use thicker tube. The attachment is of a more innovative frame by Owen Greenwood, early 60's. Paul.