Four dynamos, two per wheel, wired up to a big fan mounted on a rear rack ( a bit like those fan boats you see in American swamps) but have the fan pointing the wrong way, blowing air forward.
The more you pedal the harder it gets
But (and here is the really clever bit) it would feel like a tail wind blowing on your back. Your mind is tuned to like (or indeed love) a tailwind…. It will completely fudge your mind up as well as your knees.
Not finished yet…. Your hair will be swept forwards at the back and swept backwards at the front. This could possibly cause (if you have good hair) a lateral left to right Mohican, not only adding comedy looks to head fudge knee killing experience, but also a larger, more visible, safer road profile.
I shall call it the “the fanny fudger”
Patent pending, already applied to dragons den.