Originally Posted by MnHPVA Guy

This is a common misconception, because Whitworth tools fit the nut and bolt hex sizes of 26 tpi fasteners.

26tpi is BSC British Standard Cycle. In most sizes this is a rather fine thread, intended to avoid loosening from vibration on cycles, motorized or not. Whitworth is a much coarser thread, similar to UNC with 55 degree threads vs, the 60 degree threads of the BSC.