Unicycles with a square axle, such as the OnlyOne unicycles and the QU-AX Luxus, are suitable for children and beginners up to approx. 75 kg. For heavier riders and for advanced riding (freestyle, hockey, basketball, etc.), a unicycle with an ISIS or Q-Axle hub is recommended for reasons of durability, such as the QU-AX Profi or Muni unicycles.