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  1. Úvod


Toto je srovnávací test různých modelů kol Rolf PRIMA v aerodynamickém tunelu. Srovnávacím modelem kol konkurenční značky byla kola Mavic Ksyrium SL. Zajímavé je to, že tato renomovaná kola poráží i jeden z nejlevnějších modelů v nabídce Rolf PRIMA - hliníková kola Echelon SL!
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Can Rolf Prima wheels make you faster? Yes!

Rolf Prima wheels are engineered to make you faster. The greatest potential for improving cycling speed is through improved aerodynamics. At 23 mph, 80% of an average riders power output is used just to overcome the wind resistance. We have designed our wheels to decrease the wind resistance, meaning more of your power goes into relentless forward motion.

Rolf Prima wheels provide a significant improvement in speed through the use of aerodynamic components, optimized rim profiles, paired spoke technology and hidden spoke nipples. This makes Rolf Prima wheels the best performance upgrade that you can make to your bike.

Time saved is in comparison to a Mavic Ksyrium SL.

What does this all mean for you?

Every second. Every watt. Every time you are digging deep in the aerobars or powering off the front, the less you fight the wind and the more you benefit from your work. Upgrading to Rolf Prima wheels can make you faster compared to the wheels you’re riding now. Beyond that, Rolf Prima wheels are also designed to be fast across the board, not just in very specific conditions. See below for more technical details on Rolf Prima’s wind tunnel results.

Important points about Rolf Primas aerodynamic testing:

Wind Speed. A common concern about wind tunnel testing is the speed at which the wheels are tested. Aerodynamic testing of bicycle wheels is typically performed in a wind tunnel at 30 mph (48 km/h), with the wheel spinning at the same speed. This speed is useful for standardization of the tests and is directly applicable to professional cyclists that often ride at this speed. The data is scalable to slower speeds, but the wind angles dont translate directly. Wheels optimized for 30 mph most often have a specific wind angle at which they excel. This is appropriate for professional cyclists that travel at these speeds but these wheels can actually be slower when ridden at speeds that are typical of different disciplines, or different caliber athletes. Rolf Prima wheels are designed to excel in all wind conditions to give the rider the confidence of knowing theyve picked the right wheel set for the day regardless of the wind speed and direction.

Time saved. Time saved changes based on how fast the cyclist is riding because Time Saved is a percentage of the time a rider is on the course. The slower a cyclist rides, the longer they are on the course meaning more time that can be saved.

Take for example a 40km (25mile) time trial. If you ride it at 25mph it will take you 60-minutes to complete the course. If you were on Rolf Prima TT85s you could save 1:28 off your final time, giving you a finishing time of 58:32. If you rode the same 40km (25mile) course, but rode at 20mph your final time would be 75-minutes and you could save 1:49, giving you a finishing time of 73:11.

Time saved calculations. The drag figures are normalized for the NACA "standard day" which is 60°F, 29.92"Hg, at sea level. All tests were performed in the wind tunnel at 30mph with the wheel spinning at 30 mph. Aerodynamic drag was measured and converted to time savings over a distance based on a formula developed by Chester Kyle (ref Cycling Science, Spring 1995).

Comparison (Control) wheel. The Mavic Ksyirum SL was chosen as the comparison wheel because it is a common road wheel and it is a wheel people are familiar with and may have ridden. Some companies compare to lower end wheels for wind tunnel tests, but we wanted to compare to a wheel that is higher end and common. It is a 20H radially laced front wheel with aluminum bladed spokes.

Wind angle. The time savings shown is for riding in a 15° wind angle. This angle was selected because it is the most common wind angle for a cyclist travelling between 20-25mph given variable conditions calculated from national average wind speed and random wind direction. For the TT85 and TdF85 a wind angle of 10° was selected as more suitable because it is more likely to be ridden at higher average speeds and used when there is lower likelihood of high cross winds.

A note on wind speed and wind angle: The national average wind speed in the US is 9.2 mph. A cyclist riding 20 mph in this average wind will see an average effective wind angle of 17.2°. At 25mph the average effective wind angle reduces to 13.6°. Increase the speed to pro-level speeds (30mph) and this average wind angle reduces to 11.3°.

Tire. Tubular wheels were tested with a 21mm Vittoria Open Corsa CX tire. Clincher wheels were tested with a 20mm Vittoria Open Corsa CX. These tires were selected because they have identical treads and despite the labeled size, their mounted widths are nearly identical. This minimizes the influence of differences between the tires on the test results, ensuring they are comparable.

Wind tunnel. Rolf Prima tested wheels at the A2 wind tunnel. The results of this testing show us the reduction in drag compared to a standard wheel, allowing us to calculate the time savings over various distances. The A2 wind tunnel is located in Mooresville, North Carolina and is a smaller version of the AeroDYN Wind Tunnel, located next door, which is the leading facility for NASCAR teams to validate racecar designs. With a similar reputation for reliability, the A2 tunnel is the choice for a number of industry-leading manufacturers.

Společnost HISPORT Czech Republic, spol.s r.o. dále nabízí produkty těchto značek:

© Copyright 2019 / ROLF PRIMA / HISPORT s.r.o. / All rights reserved
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