WHY IS WHEEL STIFFNESS IMPORTANT?
Minimising power loss is critical for speed and efficiency. The more a wheel deforms under force, the more energy is wasted.
WHAT TYPES OF WHEEL STIFFNESS ARE TESTED?
Transmission stiffness determines how much torsional flex a complete wheel displays when load is applied. This simulates pedalling torque at the freehub. Lateral stiffness determines how much lateral flex a complete wheel shows when side load is applied. This simulates force generated when rocking the bike side to side, on a climb for example, or when going into a corner. Less torsional and lateral flex mean increased rider input and less energy wasted as well as added stability and control under cornering load.
HOW IS WHEEL STIFFNESS TESTED?
For transmission stiffness testing, the rear wheel is secured at the axle, the valve hole in the rim is fixed and torsional force is applied to the freehub. The more the hub rotates, or “winds up”, within the wheel torsionally, the less transmission stiffness the wheel has. For lateral stiffness, both the front and the rear wheel are locked at the axle and lateral force is applied to the rim. The more distance the rim moves laterally, the less lateral stiffness it has.