retrodirect

Darcy brought his bike in the other day. He modified it to use a retro-direct drive train.

Staring at this picture is like looking at M.C Escher.
I have to admit, this was the first time I had ever seen a set up like this. But it is not new. There are two freewheels on the back hub. One engages when the rider pedals normally. Nothing weird so far. The rider is able to coast, but when pedaling backwards, the other freewheel engages and the normal freewheel, well, freewheels. Whoa!

The two freewheels are different sizes, so it is essentially a two speed gearing. Pedaling forward is one speed, pedaling backwards is another speed.

This throws all the theories about cycling bio-mechanics and physiology out the proverbial window. It's sort of cool but leaves me thinking that just because something can be done, doesn't mean it should be.