Parcours and Panaracer Partner to Create the Parcours FKT Aero Gravel Wheelset

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Today Parcours is acknowledging that gravel is getting faster and aerodynamic optimization is maturing. The Parcours FKT aero gravel wheelset is wide and light with aero optimization around a 40mm tire but that’s not where it ends. Instead of a generic tire, Parcours is choosing to partner with one of the most popular gravel race tires on the market.

If you like the idea of going fast on gravel, this is a wheel that is going to catch your eye. Did Parcours just blow up the gravel wheelset market? Or is this just a bunch of marketing with little use in the real world?

Wider is faster

With aerodynamics there’s always a push/pull relationship between pure aero performance and the needs of a rider. There’s little debate that the smaller you can make the front of a bike, the more aero it is. For better or worse though, tire size needs to increase for comfort and traction on gravel. That means the wheel itself has to optimize the aerodynamics around a wider tire and that means a wider wheel.

According to Parcours, the push pull doesn’t end with the tire size vs aerodynamics discussion. Even once a brand decides to optimize around the wider tire, there are still considerations. Basically you have to balance real world needs such as weight, cross wind performance, frame space, and ETRO guidelines against the absolute best aero performance.

Balancing those needs for the Parcours FKT gravel wheelset meant landing at an hookless internal rim width of 27mm with a 40mm external width and a depth of 47mm. That internal width allows riders to choose to pair a tire as narrow as 35mm while still staying in the good graces of the ETRTO. Meanwhile the external width is as wide as is physically possible while still fitting into the vast majority of modern gravel frames. Arriving at the depth was a more complicated process.

Parcours shares that the process started in 2019 with the “#thinkwider aero design project.” This was initially focused on road wheels and showed that “the sweet spot for rim depth versus tyre width began to show diminishing returns at a ratio of > 4:1 (depth:width).” Unfortunately as you increase the tire size to “40mm+ this would imply a total rim depth of ~120mm+” and an unworkable design in the real world.

To solve this paradox, Parcours used a combination of CFD, 3D printing, 3D scanning, and finally wind tunnel validation. The process was to first use CFD and run through a range of sizes and shapes. The goal was to find the best performance when the tire is the leading edge, at the front of the wheel, and when the wheel is the leading edge at the rear of the wheel. The results of this process were then 3D printed for validation.

Tire tread is important

It was at this point in the process that tire tread became an important part. Just as Dylan Johnson showed before Unbound, Parcours was seeing significant aero differences with different tire tread patterns. The brand even reports that “3rd party testing has shown that the difference between two different tread patterns of varying ‘roughness’ could be >7W at 48kph / 30mph test speed.” So instead of trying to optimize for any tire, Parcours picked the Gravel King X1.

Reading through the details, it sounds like the specific tire chosen is actually less important than choosing one. It would have been possible to design a fast wheel for a different tread pattern. That left the choice to come down to preference and the “Panaracer Gravel King X1 was chosen as the benchmark tire based on extensive discussions with athletes around their race use case.”

Then, during development, prototypes were 3D printed and assembled into complete wheels. This allowed Parcours to mount a test tire before 3D scanning the complete unit back into CAD software. “This ensured that when moving onto the CFD testing stage of the process, the impact of the tyre on airflow could be more accurately modelled.”

Parcours FKT aero results

Parcours touts the final windtunnel results as proof of the design process. Starting with the road specific aero wheelset Parcour Ronde as a baseline, the new Parcour FKT aero gravel wheelset shows a 6.2 watt savings when mounted with 40mm Panaracer GravelKing X1 tires. That translates into a theoretical 6 minute and 25 second time savings at Unbound and Parcours claims it’s 6 watts faster than the Zipp Firecrest 303.

Wheel aero test results

For those looking to play with tire size, Parcours has some info on that front as well. What the brand saw was that when testing 35, 40, and 45 mm widths, “at lower yaw angles (up to 10°), the 45mm tyre showed increased drag, but at wider yaw conditions the impact was far less significant.” If you expected that, what’s even more interesting is that “35mm & 40mm tyres performed very similarly across the full yaw sweep.”

Tire width aero test results

Parcours goes on to give some advice as you consider your next gravel race. The brand says that “choosing to run a 45mm GravelKing X1 over a 40mm GravelKing X1 would lead to an estimated time penalty of 2 minutes 36 seconds at Unbound Gravel. However, with the associated improvement in traction and control, in some circumstances and for some races this may become the preferred setup.”

Tire aero test results

Parcours FKT Pricing, specs, and availability

As of today, “Parcours FKT wheels are available to pre-order through July for delivery in August. All wheelsets ordered during pre-order in July will be shipped and include a pair of Gravel King X1 tyres.” Visit Parcours.cc for more information and purchasing

Price: £1,199 / $1,599 / €1,559

Weight: 1,500g

Rim depth: 47.0mm

Max rim width: 40.0mm

Internal rim width: 27.0mm

Note: ETRTO compliant with 35mm+ tyres