Skeptics of 27.5in wheels who were holding on to hope that traditional 26in wheels would live on in the downhill world can lay down their arms and raise the white flag in defeat.
Not only were this year's men's and women's UCI World Championships both won on 27.5in wheels, but middle-sized wheels nearly captured the entire podium on each side.
Madison Saracen rider Manon Carpenter did one better, by taking the overall UCI series title as well.
She did so on a new prototype Saracen Myst Team Issue. Madison Saracen Team mechanic Alex talks us through the bike in the video below, and you can see a whole host of photos of the bike in the gallery above:
Video: Manon Carpenter's Saracen Myst Team
Saracen builds Carpenter's frame with a moulded carbon fibre swingarm and a TIG-welded aluminium front-end – a construction technique that offers some of the weight and stiffness benefits of composite construction, but with the more quickly changeable geometry that only comes from mitred tubes.
The TIG-welded front triangle can be more quickly changed than one made of moulded carbon fibre
According to team mechanic Alex Lovett, this new frame not only features additional clearance for the bigger wheels, but longer and slacker geometry too, to better handle the increasing fast and technical tracks of modern downhill racing. There's also internal cable routing through the swingarm, a revised shock linkage and a notably bigger and burlier hydroformed seat tube.
The all-new frame is built around 27.5in wheels
Carpenter's bike is equipped with a full Shimano Saint group, including the relatively rare Shimano SMCD chain guide. Vented Shimano Freeza rotors are used at both ends but Carpenter prefers a slightly smaller 180mm disc out back to complement the 203mm's greater power up front.
Factory-tuned Fox suspension is used at both ends – including the highly tunable RAD rear shock with independent high- and low-speed rebound and compression damping adjustments – and Shimano sub-brand PRO fills out the cockpit, complete with a bar trimmed down to 750mm from the stock 800mm.
Shimano's SMCD chainguide looks to be well engineered, and it's impressively sleek
The wheels are straightforward – on paper – DT Swiss FR570 rims laced to Shimano Saint hubs and wrapped with sticky 27.5 x 2.4in Continental Kaiser Projekt tyres. As is fairly common practice among many top riders, however, the wheels are built with surprisingly low spoke tension.
While the idea of a flexier wheel might seem counterintuitive, Lovett says that this allows the wheels to deflect around obstacles instead of bending (or breaking) on impact – a key attribute considering that Carpenter runs tyre pressure as low as 18psi, depending on course conditions.
Lower spoke tensions boost wheel durability on rougher tracks
Whatever Carpenter is doing, it's clearly working.
Complete bike specifications
- Frame: 2015 Saracen Myst Team Issue, size large
- Rear shock: Fox DHX RAD
- Fork: Fox 40 Float RAD
- Headset: Works Components Angleset
- Stem: PRO custom direct mount, 45mm
- Handlebar: PRO custom, 750mm width x 20mm rise
- Grips: Saracen lock-on
- Front brake: Shimano Saint BR-M820 w/ 203mm RT99 rotor
- Rear brake: Shimano Saint BR-M820 w/ 180mm RT99 rotor
- Brake levers: Shimano Saint BL-M820
- Chain guide: Shimano SMCD-50
- Rear derailleur: Shimano Saint RD-M820
- Shift levers: Shimano Saint SL-M820
- Cassette: Shimano Ultegra CS-6700, 11-25T
- Chain: Shimano XTR CH-M981
- Crankset: Shimano Saint FD-M820, 165mm, 36T
- Bottom bracket: Shimano SM-BB93
- Pedals: Shimano DX PD-M647
- Rims: DT Swiss FR 570, 32h
- Spokes: DT Swiss Competition w/ alloy nipples
- Front tyre: Continental Kaiser Projekt, 27.5 x 2.4in, 18-23psi
- Rear tyre: Continental Kaiser Projekt, 27.5 x 2.4in, 18-23psi
- Saddle: PRO custom
- Seatpost: PRO custom
- Total weight: 16.99kg (37.46lb)