Dust in the Wind

Kites rise highest against the wind . . . not with it.

—Winston Churchill

The wind is a constant consideration with cyclists. How aerodynamic can I make my helmet, my bike, or myself for that matter? Many bicycle manufactures use wind tunnels and Computational Fluid Dynamics (CFD) to understand their product in relation to fluidity of wind over bike and rider. Drag is the enemy. Recent tests at the San Diego Air and Space Technology Center Low Speed Wind Tunnel show where most of this drags ends up.

  • Handlebar           30%
  • Front Wheel        16%
  • Frame                   16%
  • Fork                        9%
  • Bottle                      9%
  • Powertrain            9%
  • Front Break           3%

All this aero talk is great on the flats. What about the hills? Most of us would immediately say that the light frames dominate the aero bikes when climbing is involved. But according to Tour Magazin, they might reply . . . Nicht so schnell, mein freund! Yes, when climbing ridiculous grades of 18% and up, the lighter frame is the way to go, but most of us don’t ride those grades on a regular basis. Most of us also do not have the advantage of waking up and thinking about the course we are riding and choosing the R5 over the S5 or the Venge over the Tarmac. So for the typical rider, testing shows some interesting results.

Between the very high grades and flat ground, there are the grades where light bikes and aero bikes equally fast. Where is this gray area? For a light bike with a professional rider on board, it is about 8% and below. For the average Joe on the same bike, the grade is about 5% and below. That means from those grades and below, speed is still involved and drag is still important. Sooooooo . . . when hills are very steep and speeds drop and drag is almost non-existent, it is obvious which bike is better. BUT for day-to-day riding on “typical” terrain, the results of Tour Magazin‘s test shows that the aero bike is a better all-around bike.

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