The smallest pit bikes, such as a 50cc can go about 25 mph (or considerably less if they have got a limiter), when the fastest products can go sixty+ mph. The top speed largely depends on how strong the motor is and what the transmission and gearing are setup for. https://go-off-road-barnsley29592.blogminds.com/are-electric-unicycles-legal-in-the-uk-fundamentals-explained-34858752