All wheel tests at TOUR take six basic categories into account: The weight of the wheelset, braking characteristics, wheel stiffness, concentricity, acceleration and options for maintenance and adjustment. Depending on the test field, we also carry out aerodynamic and durability tests. Below you will find more detailed descriptions of the individual measurement categories:
Weight
The weight of the front and rear wheel is assessed, if necessary with rim tape but without quick release.
Brakes
The braking properties were determined on the TOUR test bench with the supplied pads in dry and wet conditions. Shimano pads are used for aluminium rims. The separate test programme for durability reveals whether carbon rims can withstand the heat of continuous braking that can occur in practice. We also record details on modulation and pad wear.
Stiffness
The wheels are firmly clamped at the hub and laterally loaded at the rim. The deflection of the rim is measured. High stiffness makes the wheel stable, precise in its riding impression and usually means a higher mechanical load capacity and longer durability. Overload tests show how the wheel behaves under high forces and whether spokes or nipples can still settle. Such wheels that have not been "squeezed" are characterised by larger tolerances in the subsequent concentricity measurements.
Concentricity
Lateral and radial run-out are determined before and after the stiffness test; the values after the stiffness test are included in the assessment.
Acceleration
Laboratory measurement of mass inertia. The values indicate the energy required to accelerate a wheelset with tyres to 30 km/h. Lower values are better. Lower values are better, but a bike with low acceleration values also rides more nervously than one with high values, which is not always desirable. On fast descents, a bike with high acceleration values runs more safely.
Maintenance and adjustment
The ease of repair (centring, type of spokes, any special tools required, bearing replacement) and the adjustment options (bearings) are assessed.
Aerodynamics
In the wind tunnel, we measure the air resistance of the wheels, installed in a complete bike (Canyon F8) and with a dummy with pedalling legs. The drag of the entire system is measured in each case, with only the test wheels being swapped. The wheels are subjected to airflow at angles of -20° to +20° and the measured values are weighted according to their probability of occurrence.
At the same time, we use a steering torque balance to determine how much crosswind can be felt in the steering.
Endurance run
On a drum test bench from tyre manufacturer Schwalbe, the rear wheels run at 40 km/h for 5,000 kilometres under a load of 65 kilograms. The rollers are fitted with 2.5 millimetre high obstacles; for the spokes, this means around nine million impacts in addition to the loads at the wheel contact point.
Impact resistance
Carbon is strong but brittle. Is the wheel ruined if you hit a pothole? We test this with our own impact test in the TOUR laboratory. A plastic hammer falls on the rim flange and we test whether permanent damage occurs with three drop heights.
Jens Klötzer
Editor
