the invention disclosed herein is a light weight , mountain bicycle competition wheel rim . the invention provides improved fatigue and impact resistance compared to prior art designs . the invention makes maximum use of advanced , high strength aluminum alloy materials , improving its stiffness - to - weight and strength - to - weight ratios . the superior structural performance of the invention is provided by a unique truss type section geometry that efficiently utilizes the material to maximize bending and torsional stiffness and strength while minimizing weight .