The road bike handlebar is a very special "handlebar". So many bends on so few metres of tube result in a wide variety of grip positions. You can grip at the bottom or at the top, or - as most people do - in the centre and on the shift brake levers. But there is also room for gripping between these three positions. This variety is nice and useful. But when things get really fast, there's an obvious problem: no matter where you grip the handlebars, the air resistance is too great. You can really feel the wind pressure when your upper body and arms are pushing against the wind like an open funnel. And even if you press your nose against the stem and your legs hammer against your chest, your arms are still in the wind. Ever since Greg LeMond won the Tour de France in a time trial final in 1989, cycling has known the solution to this problem: the arms have to be in front of the body. LeMond took over the aero handlebars from the triathletes - an attachment to support the forearms in front of the body. From the front, you can see the difference quite clearly: the frontal area of the cyclist is considerably reduced compared to the classic lower handlebar position, which has a direct impact on the possible speed.
Technically speaking, the product of the frontal area and the cd value is decisive for the resistance that the driver experiences due to the airstream. Aerodynamic drag clearly dominates the overall drag with a share of around 80 per cent. The cd values of racing cyclists are unfavourable and are around 0.5, and little can be done to change this, even with an optimised posture. What you can influence more is the frontal area - in simple terms, the area that the cyclist covers when viewed from the front in a photo. In every time trial competition, from the short triathlon to the Tour time trial, time trial handlebars are therefore used today to reduce the frontal area and thus the air resistance. However, these aids are prohibited in normal cycling races and most amateur events.
We wanted to find out how big the difference between the racing bike and time trial position really is and what matters in detail. We worked with amateur athlete Thomas Hohenberger, a good time trialist and triathlete, on the cycle racing track in Augsburg to analyse the influence of the riding position on air resistance as well as twelve posture and equipment variants on a total of three bikes (see page 12). The result of these measurements: From the brake grip position on a road bike to the optimised time trial position on a time trial bike, air resistance is reduced by 25 percent. With the same pedalling power, this means that an age-group triathlete rides at 35.7 instead of 32.7 km/h, a professional time trialist at 50 instead of 45.6 km/h. Aero handlebars are therefore a must for races - if they are authorised.
You can read the full story, including a detailed guide to a better riding position in twelve steps, in the 36-page Time Trial & Triathlon special in TOUR 5 - you can find the PDF download right here below.
In the Video TOUR author Robert Kühnen shows and explains how we carried out the test rides for this story on the Augsburg velodrome
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