TUNNEL BENEFITS
We highlight the importance of entering the wind tunnel for this grouptest
THE R. J. MITCHELL
Wind Tunnel at the University of Southampton is one of the world’s most respected. Prior to our testing we consulted with several aerodynamicists to establish the best method. One referred to this tunnel as ‘the gold standard’ for its excellent flow control systems that ensure the chop from the fans is smoothed and that the air meeting the test subject is consistently uniform. It’s no surprise, then, that it’s the go-to facility for Team GB, many pro teams and manufacturers.
BASED ON EXPERT
advice, we tested the wheels at two angles, 5º and 12.5º, in a tri bike with a pedalling rider. We used control tyres and even control cassettes, with a 28t top sprocket because it’s in the wind. It’s exciting to first step foot in the tunnel. Your bike gets set up on the balance, the device that measures the drag force. This is like a set of scales but measuring how much the passing air is pushing you back – the more aerodynamic the total bike and rider system is, the less the air pushes you back.
THE AIR SPEED
is adjustable up to 90mph, enough to test scale models of aircraft. We did all of our testing at 30mph; this is faster than typical tri speeds but it’s the speed at which most manufacturers test and it adds resolution to the data compared to lower speeds.
AT THE START
of each run you have to hold still for a calibration, then the fans start and you begin pedalling, which brings a big surprise. The rear wheel is on a drum with a big flywheel. Once spinning, it only takes about 150W to keep it going but getting it moving in the first place takes a big shove. In total we rode for two hours, always concentrating hard to hold our best position.
THANKS TO MICHELIN
for supplying the Power 4 Competition clincher as a control tyre. This was our first experience of it and it’s fast, and grips well in the wet and dry. Other versions are available at michelin.co.uk. And thanks to Prestige Cycles for setting up the test. Prestige run aero set-up sessions for triathletes at the University of Southampton, plus bike fit clinics in store. They’re the UK agent for Dimond tri bikes alongside a range of bespoke road bikes.