Chain-driven unicycles. use of a chain can make the unicycle much taller than standard unicycles (note that multi-wheel unicycles can be described as giraffes). Standard unicycles don't have a chain, which limits the seat height based on how long the rider's legs are, because there the crank is attached directly to the wheel axle. Giraffe unicycles can range in heights from 3 feet to over 10 feet high.