Features: The smaller the number of teeth, the faster the speed. If the rear flywheel has 16 teeth, then if the rear flywheel has 12 teeth, its speed can be increased by 30%. It can be said to be a sharp tool for speed increase. Specification: 12-tooth rotary flying (live flywheel) wheel The inner diameter of the thread is 34MM, the thread depth is 10.5MM, the inner hole is 18MM, the total thickness is 26.5MM, the maximum diameter of flywheel teeth is 53MM, and the weight is 115g g. 14-tooth rotary flying (18mm) live flywheel The inner diameter of the thread is 18MM, the pitch is 63mm, the thickness is 21mm, the maximum outer diameter of the flywheel tooth is 62.5mm, and the weight is 150g. 14-tooth rotary flying (live flywheel) wheel The inner diameter of the thread is 34MM, the thread depth is 10.5mm, the inner hole is 22mm, the total thickness is 22.5mm, the maximum diameter of flywheel teeth is 61mm, and the weight is 140 g. 16-tooth rotary flying (live flywheel) wheel The inner diameter of the thread is 34MM, the pitch is 69mm, the thickness is 14.5mm, the outer step step is 54mm, the weight is 135 g. 18-tooth rotary flying (live flywheel) wheel The inner diameter of the thread is 34MM, the pitch is 76mm, the thickness is 14.5mm, the axial direction of the outer step is 55mm, and the weight is 165 g. Product type: 12-18T bicycle flywheel Material: steel Model: single speed flywheel Lists: 1 * Bicycle freewheel Notes: 1.The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. 2.Please allow slight manual measurement deviation for the data.