Aerodynamics - Impellers
Wheels offer the greatest tuning potential for making a road bike faster. Accordingly, TOUR Impellers tested in various forms in the GST wind tunnel. The wheels are always measured as part of the overall system of bike and rider, "as measurements on the naked wheel are misleading," says TOUR test engineer Robert Kühnen. In order to obtain realistic results, the dummy with rotating legs has been used since March 2013, as the rider's leg position influences the air resistance of the rear wheel and therefore the overall concept in crosswinds. Speed can be increased especially with high and favourably shaped rims. Current (aero) models with a rim height of around 60 millimetres have - measured with rotating legs and a relatively non-aerodynamic reference wheel - an air resistance of around 216 watts (TOUR 1/2022).
Aerodynamics - Helmets
Does an aero helmet make you faster? TOUR has already investigated this question in several wind tunnel tests. In contrast to the test set-up for complete bikes, the full-body dummy is used, which sits on the reference bike in a typical racing bike position - with the back inclined at around 15 degrees. The total resistance of the bike plus rider with helmet is measured. So far, our results have shown that an aero model can provide an aerodynamic advantage of around 10 watts compared to a conventional helmet.
Aerodynamics - Suits
Ahead of the 2018 Tour de France, we wanted to find out exactly how windproof professional racing suits are. Instead of the dummy, a flesh-and-blood rider took a seat on the bike and let the cold wind blow around his nose in a thin one-piece suit - with two findings. Firstly: Special aero clothing leads to a considerable speed boost, saving around 30 watts. Secondly, the dummy copes much better with the sub-zero temperatures in the wind tunnel.
Unique specimen
Francesco Moser's world hour record bike from 1988 is still the most spectacular bike that TOUR has ever tested in Immenstaad. 25 years after the Italian's record-breaking ride (50.644 kilometres) on the track in Stuttgart's Hanns-Martin-Schleyer-Halle, we collected the unique bike from Moser himself and subjected it to a not entirely serious comparison with current time trial bikes. The bike performed remarkably well and came quite close to the aerodynamics of the time trial bikes, but the huge 103-centimetre disc on the rear wheel also revealed the biggest weakness: Moser's bike would have been almost impossible to ride in the wild and in crosswinds.
Julian Schultz
Editor
