While it seems some manufacturers are approaching the new ‘plus’ wheel size with a little caution, Scott appears to be fully committed, launching 11 new plus bikes across its mountain bike range. Established models including the Scale, Genius and Genius LT all receive the 27.5+ treatment, along with Scott’s new electric full suspension offering, the E-Genius.
We headed out to Massa Vecchia, Italy to find out all about the bikes and see how they behave on the trails.
“Go for Plus and find an entirely new riding experience”, Scott Sports claims. But what are the contributing factors that could, potentially at least, sway people towards these fatter beasts?
Scott worked closely with German tyre company, Schwalbe on this project and tested a variety of different widths before settling on the 2.8in tyres seen here. “In the beginning we had 3in tyres. That’s what we started with. When we started doing test rides, we decided that this wasn’t the best size because they have a negative effect on the agility of the bike”, says Schwalbe’s head of product management Marcus Hachmeyer.
Settling on 2.8in tyres meant wheel weight and rolling resistance was reduced (compared with the early 3in prototypes) and the bike became more nimble on the trail. In fact, Schwalbe claims the rolling resistance of the new 2.8in tyre is only one percent higher compared with a 2.35in tyre.
The new Genius 700 Tunes Plus rear end comfortably fits the 2.8in tyres that Scott specs as standard
Worried about the weight? With the standard SnakeSkin sidewall, Schwalbe claims its 2.8in Nobby Nic tyre weighs approximately 800g, keeping them within the realms of narrower 29in tyre weights. So, just as you’d expect, they’re not the lightest tyres out there and are ever so slightly more reluctant to roll, but that extra width does bring some substantial benefits.
First off there’s the increased contact patch which helps contribute to some substantial gains in traction. According to Schwalbe, the 2.8in Nobby Nic has a 21 percent bigger contact patch than that of a 2.35in Nobby Nic. Then there’s the increased resistance to pesky snake bite punctures. Schwalbe says the wider tyres can reduce the risk of snake bite flats by eight percent (it’s worth noting that these stats were produced when testing the tyres with what Schwalbe considers recommended pressures for each of the widths – 1bar in the 2.8in tyre and 1.7bar in the 2.35in tyre).
With rim width dictating so many critical factors when it comes to the overall performance of the bike, using wider rims not only increases tyre volume (which helps to improve ride comfort) it bolsters tyre stability and allows you to run much lower pressures. This in turn bolsters the amount of traction on offer.
After some time testing a variety of tyre and rim combinations, Scott decided to go with a 40mm (internal width) rim. “We decided to use a 40mm rim as it’s the best compromise”, says Rene Krattinger, Scott’s product manager, who led the development of its Plus sized bikes.
“With the 30mm rim you already have the tyre moving much more than with the 40mm rim, especially at low pressures,” he continues. “This 40mm here is only 60g heavier than a 30mm 29er rim. The weight penalty is quite small.” On the subject of weight, it’s worth noting that Scott was keen to point out that the overall weight penalty for the complete wheelset (tyre and rim) is 250g over the equivalent 29in wheelset with 2.25in tyres fitted.
The total wheel diameter with a 2.8in tyre fitted is almost the same of that as a standard 29in wheel with a 2.3in tyre (the plus size wheel is approximately 10mm smaller), meaning the plus-size