ARC8 EVOLVE FS

At sub 10kg, the ARC8 Evolve is a lean XC race machine – but is it mean enough to win?

¤8,999 • 29in • arc8bicycles.com

When it comes to XC racing, weight is of critical importance. The riders are lean, and the bikes have every ounce of excess fat trimmed back too. It’s all about optimising the power to weight ratio of rider and machine to increase their chances of success on race day.

But long before the start gun sets heart rates rocketing, rider prep starts in the off-season and at the same time bike engineers are looking at ways to minimise frame weight without compromising stiffness. It’s one thing sitting at a computer manipulating layers of carbon, but it’s a very different situation if you live in Taiwan and work directly with the factory. And that’s exactly what Jonas Mueller, the engineer and co-founder of ARC8 does.

And it’s by having a much better understanding of the manufacturing process, that ARC8 is able to make such impressively lightweight frames. At the launch of the Evolve FS in Massa Marittima, Italy, I was blown away by the sub 10kg XTR build with regular, albeit fairly lightweight, high-end components. No custom ultra-light kit with questionable durability needed to reach the impressive weights achieved in large part by the 1,240g frame weight.

Take a closer look at the ARC8 Evolve FS and the suspension design lends itself to weight saving too. Instead of having a rotating link to drive the shock, a linear rail takes its place, the shock driven directly by the seatstays. Most XC bikes use short links to save weight but shorter links also generate bigger variations in the leverage rate. By using a rail, ARC8 achieves an infinitely long link, which gives a more consistent and progressive leverage rate across the 110mm of rear travel.

Like most XC bikes, flex in the slender carbon seatstays eliminates the need for a pivot at the rear dropout. And because the more traditional swing link has been replaced by a sliding rail, the seat tube doesn’t need the same degree of reinforcement to support the forces a link typically generates. So again, the frame can be made lighter without compromise.

The reversed main pivot is also a key part in the construction process. With the swingarm going inside the front triangle rather than around it, the bearings can be placed further apart to improve stiffness. The void that the swingarm fills is also a great place to remove mandrels from the front triangle during the construction process so, less filler and resin can be used in the finished product. Which again makes it lighter… there’s a theme here, right?

The frame is made lighter without compromise