SHAPE MATTERS - Aerodynamics
Many of you starting to read this section about the aerodynamic characteristics of the CAMERIG44 wheels have probably been at similar sections on websites of other wheel brands as well. Are you, just like us, wondering how it is possible that most wheel brands claim that the wind tunnel test results indicate that their rims and wheels are the fastest?
Aerodynamics is the most complex topic in bike wheel development and the methods to prove enhancements are the subject of many controversial and ongoing discussions. We appreciate the benefits of wind tunnel, computer simulations and track tests and we see the specific advantages of the different approaches, but since the rider, the bike + wheels and other external circumstances are huge influencing factors, we refrain from communicating isolated results achieved under laboratory conditions as a marketing statement. Right from the beginning, we have focused on the development of the best possible product with you, our customer, in mind.
Aerodynamics in the all-round requirements world
During the development process of the CAMERIG44 wheels, aerodynamic optimization played a very important role. Finding the optimal aerodynamic shape became even more important once we had decided that the overall all-round performance of the wheel set should not be compromised.
We couldn’t only focus on aerodynamics, but also had to keep many other aspects in mind that contribute to making the wheel set suitable for all-round use. Aspects such as handling, weight, stiffness and comfort are of great importance and we kept searching for the optimal balance between all of these contrasting attributes.
The deeper the rim, the faster the wheel?
In general, we could claim this statement is true and for certain cycling disciplines (TT, Tri, Track) at certain (pro) levels, this fact should have great importance during the development of the rim. However, the requirements for a fast, but all-round wheel are much more complex. Making the rim deeper also means that the weight of the rim will be higher and adding weight to the outside of the wheel diameter has a negative influence on the inertia of the wheel. You will then need more power to accelerate. Furthermore, wheels with deeper rims are harder to control in the event of cross winds.
Consequently, one could say that rims with a height of 30-40mm offer the ideal compromise.
Aerodynamics is important for all-round wheels but not the only key advantage
Consequently, one could say that rims with a height of 30-40mm offer the ideal compromise. Yes, in general we agree, but this compromise was too simplistic for the development of the CAMERIG44. Many tests in the wind tunnel and on the race track have proven that it is not only the height of the wheel, that influences the aerodynamic characteristics of the entire wheel. The shape of the rim can also have an important effect - SHAPE MATTERS
When observing the current developmental progression of aerodynamic road bike frames, it is striking that the classical tear drop shape, well known due to its similarity in appearance to the wing of an airplane, is outdated. The explanation for this is simple and caused by the relatively low speed of a bicycle. The typical airfoil design plays to its full strengths at speeds of above 100km/h.
Today many leading road bike manufacturers pursue the Kamm tail principle, which was invented in the 1930’s by Wunibald Kamm, a German engineer. In contrast to a typical aero shape, the Kamm profile is flattened at the back.
As long ago as the 1930’s the Kamm principle was used for the tail of cars
Using the Kamm principle in the context of the relatively low speeds of a bicycle, one can make use of the theoretical aerodynamic advantage of a high profile even if the real height is lower. Some frame manufacturers call this “virtual airfoil”.
Besides improved aerodynamics this design principle offers further advantages:
- Higher lateral stiffness
- Lower weight
- Higher riding stability in crosswind conditions
- Better vertical compliance (comfort)
Within the development process of the CAMERIG44 rim, we transferred this approach into the design of an aerodynamic rim in a hitherto unseen and unique manner. By doing this we call the CAMERIG44 an “Aero-All-rounder”
By creating a forced flow, by means of a sharp edge, one can obtain a lager effective airfoil. A forced flow separation minimizes drag.
Finally, a wheel set is a system and therefore much more than just a rim. Thus, it is necessary take into consideration further components and bring them in line with the all-round characteristics. The rim base of the CAMERIG44 rim is adapted to a 25mm road tire, hence the aerodynamic shape of the rim is consistently maintained and turbulences between rim and tire are prevented more effectively. The advantages of wider tires are obvious and probably nobody can deny the latest research results from specialist magazines, professional teams and tire companies.
All CAMERIG44 wheels are built by hand with high quality Sapim spokes. For all front wheels and the non-drive side of the rear wheels, we use the CX-Ray spokes. With a thickness of 0.9mm and a depth of 2.0 – 2.2 mm, these high-strength blade spokes provide a very small contact surface for the wind. To increase lateral and torsional stiffness of the rear wheel, we use CX-Sprint spokes on the drive side of all rear wheels. In addition to the very stiff CAMERIG44 rim and the strong spokes, the aerodynamics of the wheel set were further improved by the use of only 20 spokes (front wheel rim brake) and 24 spokes (front wheel disc and rear wheel).
Fast and beautiful even while standing – the aero shape of the CAMERIG44 is appealing in a contemporary aero frame.