I've seen this bike catch and overtake RG500s at Snetterton with that little 500 Honda single engine.

Brilliant. Logical thinking put to practice, head angle and rake can be kept consistent, no decrease of wheel base during braking and much narrower suspension system which would be great for water cooled bikes, since the radiators receive more air that is less whirly.

I have been infatuated with this design since the early 80's. I am looking to make a replica frame for my Yamaha RD 350 engine. I need some tubing diameter and wall thickness guidance for the 4130 steel tubing frame. Ideas? references? Please post a reply.

Is this the real Hossack's channel!?

Most likely will need a heat shield for that front shock.