hhhmmmm, I think I've finally found out how to do it, if the jet becomes more efficient the nearer you come to the same speed as the air, what if you was to expand it with an expansion pipe, so it slows down from 180mph to just 90mph, I am just going to use it from 20 onwards as leafblowers or any form of jet work better the closer you get to the jet exhast's speed, it's really for coasting for long periods of time.
YouTube - Leaf blowers powered bicycle
YouTube - Leaf blowers powered bicycle