Regarding the wheel frame height choice, have you chosen the right one?

The pneumatic wheel set of road bikes is a very critical part. The same frame with different wheel sets has distinct characteristics. It is, of course, good to have several wheel sets at the same time, but is there a "one is all" wheelset? Today we will discuss this issue. In the past, we thought that the 50-frame high wheelset was a panacea, which could climb, sprint, and have decent gust stability. Before answering this question, let's first understand the aerodynamic principle of the wheelset.

Appearance

The rims of the early aerodynamic wheels were V-shaped, with narrow outer and inner widths. The aerodynamic concept was to reduce resistance through a smaller frontal windward area. Then it transitioned to U-shaped wheels, which we commonly call fat wheels, which have better crosswind stability. The latest wheel rim shape is UV-shaped. Of course, the UV shape is just a metaphor. A lot of CFD calculations are used and verified through wind tunnel tests. Big brand wheels will use more resources to design rims, to have better aerodynamic performance, which is also the most important value of brand wheels.

Rim height

 

We all know that high-rim wheels have better aerodynamic performance because they have a greater "sail effect". The so-called "sail effect" refers to the fact that when the angle between the wheel and the wind is greater than 0° (more obvious when greater than ±5°), the crosswind creates different pressure areas on both sides of the wheel. The low-pressure area will pull the wheel, and part of this force will pull the wheel forward to offset the translational resistance. As the angle increases, the translational resistance of the wheel will become smaller and smaller. Depending on the height and shape of the rim, this drag reduction can even produce negative watts for forward propulsion (the resistance is the lowest when the crosswind is ±14°).

This Shimano chart clearly shows the difference in resistance of 36, 50, and 60mm rim heights at different windward angles. The difference is not big within 10° (the main difference comes from the resistance generated by spokes of different lengths), and the difference between 10-20° is obvious. Therefore, how much aerodynamic improvement a high-rim wheel can bring depends on the weather. If there is a stable crosswind assist, then the high-rim wheel is faster. But if there is a sudden gust of wind, the high-rim wheels will become unstable, which will affect the control and even cause danger.

Weight

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Low-rim wheels have lighter rims. The closer the weight is to the outside of the wheel, the greater the impact on acceleration. Therefore, low-rim wheels are more responsive and accelerate faster. Although we can use lighter tires to reduce the weight of the wheel system, tires that take into account grip, low rolling resistance, and puncture resistance will not be too light. The weight of the outer tire + TPU inner tube and the tubeless tire + self-sealing fluid ranges from 250 grams to 300 grams. If the tire contacts the road, if the grip is not strong, you can't even accelerate at full speed, and the advantage of lightweight cannot be brought into play. On the contrary, high-rim wheels have better inertia, and the speed is easier to maintain, and it can be pushed to a higher top speed.

"All-round wheels"

For the editor, traditional comprehensive wheels such as SUPERTEAM 45MM/50MM also have good aerodynamic performance. They are also aerodynamic wheels. My cycling route has a lot of undulating roads and climbs, and I need to accelerate and climb slopes frequently. For me, SUPERTEAM 45MM/50MM is an "all-around wheel set", which is fast in climbing, stable in descending, and good for cruising. If your riding environment is changeable and there is often "evil wind", then SUPERTEAM 45MM/50MM is also your "all-around wheel set".

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And high-rim wheels like SUPERTEAM 88MM can provide a greater "sail effect", thereby achieving a faster cruising speed. For high-power riders, high-rim wheels are also more enjoyable to sprint. So can high-rim wheels climb hills? Absolutely. In the case of wind, aerodynamic wheels can even climb faster than lightweight wheels. For riders who like to brush speed and have high power, SUPERTEAM 88MM can also be an "all-around wheel set". The only problem is that it cannot be used on windy days. 50mm rim height is the "all-around wheel set" in the traditional sense. If you think that high-rim wheels are "unfeeling" and low-rim wheels are "unsightly", then it is always right to choose it.

Recommended wheels with 50mm rim depth:
S-ALL Carbon Ultra D28-50 DISC Brake
S-ALL Carbon EVO Ⅱ D30-50 DISC Brake Gold Decals