If you’re a cycling enthusiast (as I am), its always interesting to see what is on the horizon for new products (or the next gimmick). Along those lines, a (semi) recently published patent from Reynold’s Cycling addresses issues with asymmetrical wheel rims (dished rims that accommodate larger cassette sizes).
Specifically, the invention addresses the following problems, among other things:
- Potential adverse tension as the spokes attempt to align the median plane of the spoke face with the median plane of the tire interface.
- Load balancing between the flat and curved part of the asymmetric rim; and
- Lowering the wheel weight.
How does it do this? In short, by provided a rim with a straight sidewall and a curved sidewall as shown below (right – (normal rim shown left)):
While this change to the rim shape does not seem dramatic, it is somewhat impressive when viewing the entire wheel:
FIG. 1A is a standard symmetrical rim, FIG. 1B is a partial asymmetrical rim with only a partial deflection, and FIG. 1C is fully asymmetrical rim. It is very noticeable that the fully asymmetrical rim allows for (at least as shown in the illustration) uniform spoke lengths. A lack of symmetry, however, generally has it’s drawbacks – namely an unbalanced structure that would have difficulty maintaining its form under load. Reynolds’ addresses this issue by increasing the thickness of the straight sidewall relative to the curved sidewall. The asymmetry and wall thickness form the basis of the very concise independent claim 1:
a fully asymmetric carbon fiber rim comprising:
a straight sidewall, wherein the straight sidewall is thicker than the curved sidewall; and
a number of symmetric left and right spoke connecting the hub to the rim.
On my brief read of the publication, the disclosure does not appear to discuss the impact on of an asymmetric rim on aerodynamics, but possibly this design is primarily intended for shallower rims, which have less aerodynamic benefit anyway.
All in all, very interesting and likely has applicability to a mid-priced wheelset that minimizes maintenance and allows for larger cassettes.