Qu-Ax really threw away the rule book when they made the new Q-Axle series. Their new fleet of super-duper trials unicycles use a 24mm axle which allows additional hollowing (meaning they're ridiculously light) but still super rigid. This new design means that the cranks are no longer pressed on to the conical axle like the ISIS system. Instead these cranks can be precisely positioned over the axle then clamped firmly closed. This means there is zero wear between the axle and crank and the crank position stays constant. These are highly engineered cranks (with the price to match) but the work of many years R&D from the Qu-Ax team - the leading designers in next-level unicycles. This option also allows the rider to choose between 125mm and 145mm mounting points for their pedals.