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The Torqued Wrench: Aero is everywhere

  • By Caley Fretz
  • Published Apr. 25, 2012
  • Updated Apr. 26, 2012 at 12:35 PM EDT
Wind tunnel testing yields solid aerodynamic data, but can't account for real-world variables

The myth of the pack

A frequent counter to the rise of aero equipment in road racing is that once nestled inside a peloton, drafting behind a bunch of other riders, the aerodynamic gains are no longer relevant.

GC riders and climbers often make this argument, citing the fact that they never have to take a turn in the wind until the final climb.

D’Aluisio runs into this perception regularly. “When I was introducing the Venge to Saxo Bank and the Schlecks, their reaction was ‘wow, that’s cool, it would be a good one-day classics bike. But I sit in the pack all the time; I don’t need it.’”

The numbers refute this view, though. First and foremost, “when you’re sitting in the group, the air speed is actually higher for the bike than for your head, because there’s less draft down there,” explained Cote. That means there’s more air hitting your equipment than your body.

The numbers show that while overall drag of bike and rider does decrease when in a peloton, any aerodynamic improvements that are present without a draft still exist.

“The percentage decrease in drag remains the same,” explained Cote. “The overall decreases, but you still get the same percentage lopped off that total drag figure.

“If you’re in clean air, going from a Tarmac SL3 with box-section wheels to a Venge with aero wheels will reduce bicycle system drag by about 6%, or 20 watts at 40kph,” says Cote. “In a draft – and we tested this in the wind tunnel with multiple riders both head-on and in an echelon – the percentage difference was still 20%. Total drag went down for the drafting rider, but the percentage decrease was still there. In the draft, you get six watts at 40kph, versus 20 watts in clean air. The gains are still there – smaller but still significant.”

The hesitancy to go aero isn’t particularly surprising. Humans can barely detect the sort of changes brought on by most aero gear – our senses in this realm are limited to variances of about 5%. And though the math doesn’t lie, it can certainly mislead.

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FILED UNDER: Bikes and Tech / The Torqued Wrench TAGS: /

Caley Fretz

Caley Fretz

Tech Editor Caley Fretz came on board with VN in September 2010, and now splits his year between Boulder, Colorado and Annecy, France. Beyond his journalistic pursuits, he is a category 1 road, 'cross and track racer. He also holds a pro XC mountain bike license, though unlicensed racing is now more his style.

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