NOTE: Our sprocket adapters comes in three different diameter sizes: 1.0 inch, 1.5 inch, and 1.8 inch. Please choose one of adapter sizes above. 30 Tooth CNC Sprocket & Adapter Assembly High performance parts. Superior quality. Please choice between our 3 rear wheel size hub adapter. 1.0, 1.5 and 1.8 Measure your rear wheel hub before you purchase.