Triathlon bike wheels

The choice of wheels has an enormous influence on triathlon performance. Here, carbon and aluminum models are compared directly, with carbon wheels often being the first choice for ambitious athletes. We highlight the specific advantages of carbon wheels and explain why they are often superior when it comes to fighting the clock.

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The aerodynamics of carbon wheels: Where wind is decisive

Aerodynamics play a central role in triathlon, where high speeds are driven over longer distances. Here, carbon wheels excel over their aluminum counterparts:

• Shaping with carbon: Carbon as a composite material makes it possible to design aerodynamically optimized rim shapes in a way that is barely or impossible to achieve with aluminum. Through the targeted layup of carbon fibers, complex profiles can be manufactured that significantly reduce air resistance.
• High-profile rims: Less turbulence and optimized airflow: Carbon enables the production of high-profile rims. These higher rims direct airflow more efficiently. Instead of the wind breaking off abruptly on a flat rim and creating turbulent air turbulences, it can flow more gently along a high-profile rim and come back together later. This reduction in turbulence results in lower air resistance and thus to a higher speed with the same effort. Aluminum rims are generally flatter, as material processing and the resulting increase in weight would be impracticable with high profiles.
• Fewer and more aerodynamic spokes: High-profile rims often allow a lower number of spokes and/or the use shorter spoke. Fewer spokes mean fewer “annoying” elements in the airflow and therefore a lower overall resistance of the wheel. Shorter spokes also offer a smaller attack surface. In addition, carbon wheels often allow the use of Aero spokes (knife spokes) with a flattened or elliptical profile, which significantly reduce air resistance compared to conventional round spokes.
• Disc wheels: Maximum aerodynamics: Disc wheels go one step further when it comes to aerodynamics. These consist of a smooth, aerodynamically shaped surface that (almost) completely covers the rear wheel. Disc wheels eliminate the spokes and thus offer the air barely any contact surface. The airflow is directed extremely efficiently around the wheel. Disc wheels are almost exclusively made of carbon, as the low weight of carbon is essential to compensate for the additional material in the disc and to keep the rotating mass within limits. Aluminum would be unsuitable for a comparably lightweight and aerodynamic disc.
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Why only carbon for high profile and windshield?

The specific properties of carbon make it the ideal material for aerodynamically optimized wheels:

• Weight-stiffness ratio: Carbon is significantly lighter than aluminum while maintaining the same stiffness. In order to produce high-profile rims or even aluminum discs that have the necessary stability, a significantly larger use of materials would be required, which would result in an unacceptably high weight. The low weight of carbon enables high profiles and large surfaces (as with disc wheels) without excessive weight, which would have a negative effect on acceleration and handling.
• Formability: The processing of carbon fibers makes it possible to create complex, aerodynamically optimized shapes that would hardly be possible using aluminum processing methods. The ability to lay the material in different directions (layup) allows stiffness to be maximized where it is needed and at the same time to achieve aerodynamic advantages.

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Other benefits of carbon wheels in triathlon

In addition to superior aerodynamics, carbon wheels offer other benefits:

• weight: The lower weight of carbon wheels results in better acceleration and a more agile driving experience, which is particularly advantageous on undulating terrain or after corners.
• stiffness: Carbon wheels can be designed to be very stiff, which means more direct power transfer and less energy loss.
• Driving comfort: Despite their stiffness, high-quality carbon wheels can also offer a certain level of vertical flexibility and thus absorb vibrations better, which increases comfort over long distances.

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Conclusion: Carbon wheels as the key to speed

For triathletes who want to maximize their performance on the bike track, carbon wheels are usually a worthwhile (but expensive) investment. It therefore makes sense to work with two different wheelsets - a cheap aluminum wheelset for training and the expensive carbon wheelset for competitions. The aerodynamic advantages, in particular through high-profile rims and disc wheels (which would hardly be possible without carbon), as well as the lower weight and high stiffness, can save decisive seconds in competition. While aluminum wheels are a solid and often less expensive option, they generally do not match the performance of carbon wheels in terms of aerodynamics and weight. If you want to get the most out of your material, you can hardly ignore carbon wheels in triathlon.