The Belgian Martin Maes, rider of the GT Factory Racing Team won the first race of the 2019 Enduro World Series last weekend with a very particular mountain bike equipped with two different wheel diameters: 27.5 inch at the rear and 29 inch at the front. A great way to put a spotlight onthis « new » wheel format!
Indeed, Martin Maes is not totally convinved with the 29-inch wheel size for Enduro and DH. In fact during the 2018 season he preferred using the GT Fury for DH and the GT Force for Enduro with 27.5-inch wheels whereas his teammate Win Masters rode the same bikes in 29″.
The UCI has updated its regulation on the 1st of january 2019 to allow the use of two wheels of different sizes during UCI DH and Enduro races. Several Teams and pilots therefore tested different solutions. Martin Maes was the first Pro rider to take the plunge during a race, giving on the same occasion the first prestigious victory to the 97.5 format (27.5 at the rear and 29 at the front) during the Rotorua EWS.
Beware, we are not talking about the 27.5 plus / 29 tyre format, which is very popular in E-MTB and whose external tyre size is very similar (but the tyre volume is very different. The 97.5 format is very promising in Enduro (and maybe also in DH?) and it adopts 27.5 and 29 Enduro / DH tyres of standard dimensions with sections of 2.35 to 2.50.
In Rotorua, Martin Maes used a 29-inch Schwalbe Magic Mary Addix Ultra Soft Super Gravity at the front with a more rolling 27.5-inch tyre at the rear: a Schwalbe Nobby Nic Addix Soft Apex. The latter is not currently available for sale with the Addix Soft rubber, but only with the harder Addix Speedgrip rubber.
The 27.5″ rear wheel makes the mountain bike more manoeuvrable because its diameter is lower than 29 inches, but also because it is possible to use a bike frame with shorter bases. The other advantage of the 27.5 inch format is in relaunches which are easier compared to the 29-inch format due to lower inertia. The loss of traction compared to the 29-inch format is not too much of a problem for Gravity disciplines because the uphill slopes are not timed (even if some Enduro races comprise a few meters uphill).
On paper, the 29-inch front wheel improves the MTB’s ability to cross obstacles, grip and stability.
Martin Maes performed faultlessly during his first international race on a 97.5 bike mount, winning all races of Roturua’s Enduro World Serier, thus confirming that this wheel format does perform well in practice. It’s a safe bet to day that Enduro/DH pilots and MTB manufacturers will seriously look into this 27.5/29 combination during 2019.
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