SRAM Automatic 2-speed Hub Freewheel (No Brake): 36-Hole, 120-130mm Over-Locknut, 19T Cog | Tree Fort Bikes
schindelhauer bikes - Automatic gearing - how does it work? The SRAM Automatix 2-speed hub automatically shifts up a gear when you reach speed of around 16 km/h. When you slow down
Gates CarbonDrive with Sram Automatix hub - YouTube