The Minoura RDA-2429 D Bicycle Trainer features the world's only one-rim drive unit. Driven by a rubber roller contacting the rim's side wall, there will be no vibration with any tire tread, even knobby MTB tires. Complete with seven levels of resistance, it will fit any wheel size between 24 inch and 29 inch/700c. 35 mm diameter legs provide stability while supporting weight. 25.6D X 20W X 16H inches. World's only one-rim drive unit, driven by rubber roller contacting rim side wall No vibration ride no matter the tire tread, even for knobby MTB tire Seven levels of resistance Fits any wheel size between 24 inch and 29 inch/700c; 35 mm diameter legs to provide stability while 25.6D X 20W X16H inches