I'm wondering if gear changes can happen only at certain places around the circumference of that shredder disc. That would likely be a deal-breaker (or a gear-breaker). And you still have the problem of getting stuck in a high gear if something happens in front of you and you have to bag the brakes without time to downshift. What if your tire kicks a little pebble into that whirligig? Mud? They'll have to fully enclose it.

Cute, and I do admire the innovation, but somehow I can't help thinking it'll come to a sudden stop somewhere in its development.