Originally Posted by
Papa Tom
Or maybe something along the lines of the old steering wheel “Club” that would slip into the chain ring assembly and prevent the cranks from moving at all? It would have to be A LOT lighter and less bulky, though.
A small padlock through the chainwheel around the chain, perhaps?
(I'd probably choose a different lock; this is just one I had on my workbench. Hmm. And perhaps orient the lock inside rather than outside. Hmm.)
Note: the rear wheel can still freewheel and the bike can still roll forwards.