In a relatively short space of time, gravel has gone from a few buddies riding on farm tracks in the American Midwest to a UCI racing discipline with its own official world series and world championships. Former WorldTour pros win the now-iconic Unbound, and winning speeds have increased at an unprecedented rate. Lachlan Morton won this year’s 200-mile Unbound in a time of 9:11:47, an hour faster than when he won it five years ago. He was wearing a POC Procen Air aero helmet, Rapha aero socks and a skinsuit… and Parcours today launches its FKT (Fastest Known Time) wheelset, which it claims is the first aero wheel truly optimised for gravel. The brand has reverse-engineered the problem of unaerodynamic knobbly tyres on incompatible rims. Rather than looking to mitigate the aerodynamic penalty of a gravel tyre, says the British brand, the FKT is all about optimising it.
Parcours founder Dov Tate told Rouleur: “Since we know that some road tyres aren’t as quick aerodynamically because of very small micro differences in the tread pattern, intuitively, the difference between gravel tyres is going to be much higher. We did some very basic simulations on a couple of different gravel tread patterns and you could see there was a big difference.”
Parcours designed the FKT around a 40mm gravel tyre, anchored around the Panaracer GravelKing X1 tread pattern, which was chosen as the benchmark tyre based on “extensive discussions with athletes around their race use case” as well as its performance in Parcours’ testing, which concluded that airflow transitioned more cleanly from the X1’s relatively small knobbles at the tyre edge, helping it stay attached to the rim.
Optimising the FKT rim behind the 40mm tyre led Parcours to a hybrid truncated virtual foil design that the brand says “helps to manage airflow from the wider tyre, reducing turbulence caused by the more extreme tread required for gravel.” The kammtail rim profile was designed to simulate airflow conditions around a much deeper NACA-based airfoil because, says Parcours founder Dov Tate, if you were to try to create an airfoil rim behind a 40mm gravel tyre to achieve the optimal 4:1 ratio, the rim would need to be around 120mm deep – which would severely compromise handling and would be very heavy.
Parcours’ white paper, published on its website, details the test protocol and wind tunnel results comparing the FKT against its own Alta adventure gravel wheel as the baseline, as well as the commonly used Zipp 303 Firecrest. It tested the wheels at 48kph/30mph, the speed at which wind tunnel testing is usually conducted, but also at 35kph/22mph, the winning average speed at Unbound this year. From the testing, Parcours says the FKT at 48kph saves 15.6W over the baseline wheel and 6.2W at 35kph, while it saves 15 watts over the Zipp at 48kph and 6W at 35kph. Over the Unbound 200-mile distance, it calculates that’s worth six minutes and 25 seconds over the baseline and six minutes and 10 seconds over the Zipp. That's the difference between first and 13th place, Tate highlights.
Unlike Parcours #thinkwider road rims, which use differential rim profiles and depths, the FKT wheelset uses a symmetrical front/rear rim design since the brand’s real-world wind data collection process – which involves fitting sensors to the bike outdoors – showed a significantly reduced difference in yaw conditions for gravel racing environments and speeds.
The FKT has a hookless rim with a 27mm internal width, and so is ETRTO compliant from a 35mm tyre width upwards. Parcours uses a technology it calls IMPACT+ in its hookless rims: a more flexible resin is at the rim edge to increase durability and impact resistance – something that Tate points out is not possible with hooked rims, which require completely rigid ‘hooks’.
The FKT’s hubs are Parcours’ road disc model, which the brand’s supported athletes have tested and raced in triathlon and road. The drive mechanism uses a six-pawl freehub running on a 44-tooth ratchet ring.
Parcours athletes Maddy Nutt and Joe Laverick have already ridden prototype versions of the FKT to wins and top-10s at the UCI World Series, plus a podium at the Migration Gravel Race.
Last week, Continental officially launched the new Aero 111 front-specific tyre, developed with Swiss Side and DT Swiss, which we called a “new frontier of aero”. With road frames now seemingly de-optimising – or at least focusing on remaining as lightweight as possible rather than saving yet more watts – and gravel obviously not being conducive to aero frame tubes, we’re starting to see some innovation at the wheel/tyre interface, which is producing impressive gains – and other manufacturers are certain to follow with their own design collaborations.
- 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
Parcours FKT wheels are available to pre-order through July for delivery in August. All July pre-orders will ship with a set of Panaracer GravelKing X1 40mm tyres.
More information at Parcours' website.
