AERODYNAMICS

Why are aerodynamics so important for your wheels?

For example, when you go at 40km/h your wheels spin with twice the speed at 80km/h and from 15km/h air resistance is a big factor to overcome.

The force that we have to invest to go against the air or wind. The aerodynamics in Rims or wheels is something quite complex and requires an exhaustive study since many components influence.

Candle effect

In bicycle aerodynamics we talk a lot about the "sail effect" (nautical boat). We all know that a sailboat to go against the wind direction has to cross in a zig-zag manner. Although there are very small wind angles that act on the sail, they also push the object forward.

This effect is called TURBO on Progress , it reduces the air resistance depending on the height - profile of Rim, angle and wind strength. How the side wind or sail effect influences a rider:
Most manufacturers and we do wheel design and all tests with a wind simulation of 45km/h is done the sail effect is very considerable. A Rim with good aerodynamic efficiency can reduce your time over long distances in a matter of minutes.
But if the design of Rim and the shape is not well done the sail effect can be null or even the opposite can cause turbulence and a lot of air friction - DRAG.

Wind flow

The secret is to design Rims where the wind slides without turbulence at different angles from the tip of the tire to the curvature of the Rim on both sides. The better the wind is coupled laterally to the walls of the Rim the more turbo effect and thrust.

We measure this flow in the wind tunnel by rotating the wheel between 2 angles -20° to +20°. This way we see exactly when and at what angle we have the maximum efficiency and at what moment the flow breaks or detaches from the Rim.

The face tire

It is very important that it is well integrated into the Rim. Our Rims AIR+PLUS are very wide with 21 mm inside and 30mm outside that open the tire enough so that the tire walls and Rim form a line without a step. See our results expressed in Watts W...

Not all tires are recommended for time trial as they offer up to 4 extra watts in air resistance. (Direct advice on Progress or from tire manufacturers).

Resistance in Watts - W

All of us who have been through the tunnel can provide accurate information such as

  • - Angle O° (wind resistance from the front)
  • - Angle of maximum efficiency (thrust)
  • - Angle when flow breaks
  • - Candle effect (against subtraction if any)

The average of all these results indicates the resistance in (W) watts. At Progress we will offer this data in our web site or catalog soon. Data provided by the GST wind tunnel which measures 4,000 data per second.

AERODYNAMICS

Cross wind control - predicted steering

A profiled Rim influences the bike's handling and control. Side winds with strong gusts are capable of blowing you off the road. So it is important to know how to choose the right wheel for the type of trail and profile of the Rim.

It is very difficult to establish parameters as each brand is different. It also depends on how much you want to take advantage of the turbo - sail effect. On our new AIR+PLUS we use an easy to handle and safe profile with a fully rounded U-type design that reduces sidewind resistance to the maximum and is more predictable. We still recommend our model SPACE with 88m not to be used in peloton races or only as a rear wheel. In time trials and triathlons the SPACE is one of the fastest wheels on the market and the A-PRIME in the category of 40-50mm profile wheels has no competition. Our Rims up to profile 50mm are totally recommended for any type of course or wind.

AERODYNAMICS

WIND TUNNELTHE FASTEST ROAD DISC BRAKE WHEELS

It is very difficult to know exact results of different brands of wheels. The prestigious ROADBIKE magazine and one of the few, almost unique, is dedicated every year to publish scientific results of aerodynamics from wind tunnel and laboratory. We won the first test of 07/20 disc brake wheels and Rims from 40 to 50 mm. ROADBIKE 23/11 publishes another test that allows us to compare with PROGRESS. We emphasize that we test in the same wind tunnel under the same strict conditions. In addition, to contrast and confirm, we have gone to the 2 most prestigious wind tunnels in Europe,

GST Germany and the F1 France tunnel at Magny-Cours.

TEST AND RESULTS

WIND TUNNEL TEST 2019-11-28
AIRBUS, GST Windkanal, Immerstaad
Germany

WIND TUNNEL TEST 2021-10-14
AEROPTIMUM, F1 MAGNY-COURS
France