I think its time to ring Fluff brown, Mark l was told when l had my two bike that the cobra had the frame loop and the other was cougar, that came from Nicholas brown and Fluff at the time. its really does`nt matter what frame you have its still a cotton, my brother dennis raced a cotton in the sixties and it went ok, but the they are not a world beater. In saying that they are a true vintage race bike.