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You pedal the same way as normal, but the pedals aren't connected to each other (a bit like powercranks). But instead of turning the chain, it pulls the chain forwards, then snaps back like a rowing machine, as philjay said.

hummm, beg to differ.
cranks set to gallop? Look how long the crank arms are? At half stroke your rear foot would almost be at the rear axle.
I'm guessing is more like a 'step machine' motion.. ?? no?