UK aero wheel model Parcours has a brand new aero gravel wheelset out. Called the FKT (standing for Fastest Known Time), it’s used the Panaracer GravelKing X1 in 40mm width as its associate tyre in its aero testing.
Parcours says that a lot of the finest gravel bike wheels purpose to mitigate the damaging influence of large gravel bike tyres, with their extra aggressive tread sample than a street bike tyre. In distinction, it claims to have aero optimised the gravel tyre/wheel combo.
Parcours compares the advantages of its FKT wheels fitted with GravelKing X1 tyres to the distinction between using a time trial bike with climbing wheels and with a deep entrance/disc rear mixture.
Draggy tyres
Parcours discovered that the knobs on a gravel bike tyre generate vital drag (Image credit score: Parcours)
The mixture of width and tread is a big limiting consider aero optimising gravel bike wheels, Parcours says.
When DT Swiss, SwissFacet and Continental launched their new Aero 111 street bike entrance tyre, their resolution was an virtually slick tyre with small cavities to journey the airflow and generate turbulence to advertise adherence of the air flowing over the rim and thus scale back drag.
The knobs on a gravel bike tyre have the other impact, Parcours discovered, producing drag. Its wind tunnel testing confirmed that the knobblier the tyre, the extra the drag.
When it wind tunnel examined the Schwalbe G-One RS Evo Race, WTB Riddler and Pirelli Cinturato RC X on its rims, it discovered that there was a rise in drag relative to the GravelKing X1 of 10.0 watts, 14.1 watts and 15.3 watts respectively at 48km/h.
The newest race content material, interviews, options, critiques and knowledgeable shopping for guides, direct to your inbox!
Parcours attributes this primarily to the upper aspect knobs on these tyres than on the GravelKing X1. It reckons that this might equate to between 4 and 6 minutes added to trip time at Unbound.
Parcours says that there’s one other vital constraint on aero optimising wheels for gravel bike tyres: the tyres’ width. Its wind tunnel testing for its street bike wheels means that the very best aero efficiency is achieved when the peak of the edges is round 4 instances their width. This would indicate a rim depth of 120mm for a 40mm large gravel tyre.
Since no-one’s going to race gravel on 120mm deep rims, Parcours has designed its rim profile to be aero at a extra manageable 47mm deep.
The rim’s profile and 40mm width and 47mm depth are optimised for 40mm large gravel tyres (Image credit score: Parcours)
Another drawback addressed by the Parcours FKT wheels’ design is the ETRTO pointers which suggest a most rim inside width of 27mm for 40mm tyres. But it has beforehand discovered that aerodynamics are optimised with a rim that’s barely wider than the tyre, so the FKT wheels broaden out considerably from the hookless rim, to succeed in 40mm at their most width.
Despite their width, the Parcours FKT wheels have a claimed 1,500g wheelset weight. Unlike Parcours’ street bike wheels, the rim profile is identical within the entrance and rear wheels, because it discovered that the wind yaw angles skilled by the back and front wheels have been extra comparable on gravel than on street.
The Parcours FKT wheelset is priced at £1,199 / $1,599 / €1,599 and may be ordered instantly, with supply in August. Parcours is offering a free pair of Panaracer GravelKing X1 tyres with orders positioned in July.
