Originally Posted by cityevader
Wild guess, as i've never actually seen one... but based on hub diameter, and single sprocket, is that a rear hub with multiple gears built into it? A 3-speed maybe? What happens when you actually try to use it? I assume you've actually tried riding it and flipping the lever to see what would happen?
That would be my guess, I have never seen anything like that before and I have never heard of gears in the hub. But that's all that come's to mind.
Maybe thier is a wind-up spring in there and that is to release the tension to give you an extra boost.