Last month, the Bike News team conducted tests in the wind tunnel at the renowned Silverstone Sports Engineering Center, where they put WorldTour superbikes to the test. They compared these top-tier bikes with others in a direct showdown. Alongside the 11 superbikes, the team also brought their "base bike" — a 2015 Trek Emonda ALR equipped with standard square-section wheels, rim brakes, external cables, and round handlebars, without any aerodynamic optimization.

As expected, the base bike was slower than the superbikes. In their raw data, after averaging two rider-motorbike tests (one at the start of the day and again at the end), the team found that the base bike was 23.06 watts slower at 40 km/h than the average result of the superbikes. This means that to ride at 40 km/h, a rider would need to expend 23 more watts on the base bike compared to riding a typical superbike.

However, all the superbikes were equipped with aerodynamic deep-section wheels. So, what would happen if they swapped the base bike’s regular wheels for a similar deep-section option? The team decided to find out for themselves.

How much of an impact do deep-section wheels really have on cycling performance? Let’s find out!
They wanted to understand if upgrading to deep-section wheels could completely close the previous 25-watt gap. Would the performance improve significantly? And, how does the cost-effectiveness of deep-section wheels compare to something like a new helmet?
If you have an older entry-level bike like their Trek Emonda, is upgrading to aerodynamic wheels a smart investment? Do they really make a noticeable difference, or are they just for looks? They decided to find out through this test.
For the wheels, they chose a high-value option from the now-defunct British brand Prime, specifically the RR-50 V3 model.
These wheels have a depth of 50mm and an internal width of 19mm. They also mounted the same 25mm Continental GP5000 S TR tires that were used on all the other test bikes to ensure consistency. Before the brand closed, these wheels retailed for about £800 (or $900).
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The Results
They tested each bike under seven different yaw angles, which refer to the angle at which the wind hits the bike and the rider. A yaw angle of 0 degrees means the wind is hitting the rider head-on, a perfect headwind, so to speak. A higher yaw angle means the wind is coming from the side.
In this case, they tested from -15 degrees (wind coming from the left side) to +15 degrees (wind coming from the right side), in 5-degree increments, for a total of seven different angles.
The data provided by the wind tunnel is CdA, which stands for Drag Coefficient x Surface Area. The drag coefficient reflects how the shape of an object affects how easily air flows around it, while the surface area simply refers to its size. In simple terms, the lower the drag coefficient, or the smaller the object, the easier it moves through the air, and thus, the faster it will go for the same amount of effort.
This chart shows the CdA results for each bike at seven different yaw angles, ranging from -15 degrees to +15 degrees, in 5-degree increments. The higher the CdA, the slower the bike.
What's really interesting is that the deeper wheels were actually slower at lower yaw angles. This is likely because these wheels are significantly wider than our base wheels, which increases the bike's frontal surface area.
However, when the wind comes from wider yaw angles, the deep wheels really come into their own, providing more of a "sail" effect, capturing the wind and helping propel the rider forward.