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Eurobike tech: 2012 Wilier TwinFoil time trial bike

Wilier takes an unusual approach to time trial bike design

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2011 Eurobike tech: Wilier TwinFoil
The TwinFoils substantially widen the bike's frontal area, but Wilier says it in fact reduces drag. Photo: Aaron Hersh

FRIEDRICHSHAFEN, Germany (VN) — First spotted in an early incarnation at the Giro d’Italia this year, then in its final production version at the Tour de France, Wilier’s new TwinFoil time trial bikes are strikingly different from anything being produced today.

Thanks to data garnered from the wind tunnel, the Italian company has ditched the swooping gull-like tube shapes used on its old time trial bikes and has replaced them with more traditional aero profiles. The TwinFoil’s front end, though, is anything but traditional.

The TwinFoil integrates an aero base bar and front brake into two fork struts — the twin foils — which extend from up past the fork crown on either side of the head tube. The concept is intriguing and counterintuitive: while many other time trial bikes are getting progressively narrower, this design substantially broadens the bike’s frontal surface area. Wilier asserts the blades next to the head tube do in fact reduce drag, though. The foils help “direct airflow through and round body parts as well as components and wheels,” says Wilier. That reduces overall aerodynamic drag, they claim.

It takes a bit of a leap of faith to accept that a wider front end with more surface area reduces drag. But we see wide working elsewhere, on Zipp’s Firecrest rim shapes and the wide nosecone on Specialized’s triathlon-legal Shiv. Shape can trump surface area and broad components can be aerodynamic, but we’d still like to get the TwinFoil in a wind tunnel to see for ourselves.

The TwinFoil’s aerobar bolts to a proprietary stem piece that lines up with the twin blades. This modular system gives Wilier the flexibility to create a variety of stems to accommodate different fit preferences. The displayed model has a round 31.8mm clamp that is compatible with most standard aerobars.

The front brake is a V-brake design with arms that tuck neatly behind the fork blades. The housing routes next to the headtube, which we would think disrupts the smooth airflow Wilier was going for in that area. The rear brake is also a mini V-brake and is positioned under the chainstays, behind the bottom bracket. Housing routes cleanly into the stem and through the frame.

The seatpost bolt is recessed into the drive side of the frame.

The TwinFoil has vertical dropouts — allowing easier wheel removal than horizontal dropouts — that can be moved fore-aft 6mm to position the rear tire close to or far from the frame.

The frame will be available in four sizes, and geometry across the range has moderately aggressive fit coordinates and a slack 76-degree seat tube angle.