fixed gear trikes do exist though I have never ridden one. I have a threaded gear body to install a fixed sprocket on the rear axle but never tried it. Don't intend to either. Anyone want to pay $10 for it?
Paul Patzkowsky Longmont, Colorado My son had a fixed-gear trike when he was little and lived 30 years so far. He would corner like a madman--on two wheels.