[Xlot]

Yes indeed, Russell !! Except that in my case the rails are recessed and the whole assembly needs to be stiffer since the slot is just 2 mm wide - but I don't want to hijack yet another thread....
Rather :
- still another example of how those times were bustling with new ideas - is there a specific reasons why this could not happen again ?
- as for MotoGP, one issue I have is that a 1/32 track will inevitably look too narrow

Beppe

 

[Xlot]

Come to think of it.... RC motorcycles work, right ?
So, it must be that the wheels gyroscopic effect self-stabilizes the contraption - but you probably need the front wheel to steer (as well as rotate)