Basically nothing stays round under load

Basically nothing stays round under load

No, it is much. However, a wind tunnel test in which wheels are run without vertical load from the rider's weight is poorly usable. It is important to consider and normalize the vertical load, z.B. To 75 kg driver plus 10 kg wheel plus equipment such as shoes and clothing. This weight force will more or less deform the wheels when rolling, which will affect the rolling resistance. A construction-conditioned soft 16 spokes – wheel in a load-technically unfavorable arrangement can bring in thereby substantially worse values than a largely rigid 18 spokes wheel with optimal spoke arrangement or a carbon – Monocoque. These differences are noticed by any reasonably sensitive driver, and it is up to the engineers to keep the

Designing test setups with a vertical load. Basically nothing stays round under load, the question is, what deforms least??

A 21 spoke rear wheel with a moderately high aluminum rim, which for design reasons has rim sections well over 20 cm long without spoke support, cannot be mounted with the necessary tension,

Without 7 height shocks being the result. This feature only comes into play when a defined vertical load is part of the test standard. The same applies to 16-spoke rear wheels with spokes engaging in pairs on the outside of the rim. The only way to compensate for these disadvantages is with appropriately increasing rim height. The interesting point of rotational – inertial torque is readily misjudged or measured. Here we are talking about the energy resp. Power consumption of rotating system wheel independent of linear translation speed. The computational solution to this problem is a mathematical integral in which each mass of the wheel is weighted by its radial distance from the central pivot point, the axis.

Thereby external masses are weighted higher.

In principle, one should now assume that heavier rims are then disadvantageous, but this statement is quite theoretical. The absolute influence of the rotational moment of inertia compared to the total vehicle mass is as follows

Little that there is only a very slight disadvantage. On the other hand, heavier and thus usually stronger rims offer significant advantages for the deformation resistance of a wheel, which has a stronger favorable influence on energy consumption elsewhere. Here, an isolated statement about the rotational – inertia moment is misleading if it is not presented in parallel with the rolling resistance or the torque transmission. The driver has only one power, and it must be distributed favorably among the various losses with a sense of proportion and optimization.

There have been experimental setups in which wheels for measuring the rotational moment of inertia rotated, but not around their axis, but oscillated around external axes. This is physically / metrologically unfavorable, because the concrete mass distribution of the test wheel can only be determined inaccurately due to the different position of the axis of rotation. There is a mathematical conversion from a pendulum motion, which can be understood as a superposition of a translation and a rotation, to the desired "real" motion Rotation. Although this is theoretically feasible, the problem is that the isolated rotational moment of inertia in the test setup is replaced by a large amount of "normal" pop-ups Mass inertia is superimposed. This makes the calculated rotational moment of inertia much less accurate than a direct measurement, in which the sought rotational moment of inertia is already physically isolated and can be measured directly. Since there are easy to realize test setups of pure rotation, one should also proceed in this way.

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