It’s unlikely most fat tire aficionados have heard of Alchemy. The Denver, Colorado-based bike builder made its name crafting custom carbon road and cyclocross steeds. But thanks to a lending hand from suspension guru Dave Earle that may soon change.
Meet the new Alchemy Arktos (Greek for bear), a 27.5” 150mm trail bike with a Boost 148 rear end that has a unique suspension design that’s claimed to deliver both climbing stability and bottomless travel in one sexy carbon frame package.
Dubbed Sine Suspension (as in a sine wave), Alchemy says the bike benefits from a unique shock ratio curve where the rate is regressive to the bike’s 30% sag point, then ramps up prior to switching back to a regressive rate 85% into its travel. This regression is designed to counteract the progressiveness of an air-sprung shock, meaning the full travel is used — but the midstroke is still supportive.
“People in the off-road cycling world don’t often think about regressive suspension, and when they do they think of it being too soft,” said Earle, who played a role in the design of Yeti’s popular Switch suspension. “On a mountain bike, using regressive suspension in the negative travel gives the bike a much softer feel and incredible traction over small bumps, where other bikes would just skip across them. For example, the off-road racing Baja trucks have something like four feet of negative travel. When the air shock is ramping up at the end of its travel, the regressive shock rate comes back into play. The change from positive to negative and back to positive is what separates Sine from conventional dual-pivot suspension.”
Alchemy claims Sine is unlike other dual-link systems (say, Santa Cruz’s VPP). But it was the recent expiration of the VPP patent that allowed Earle to implement the new design. The full composite Arktos’s front triangle is made at Alchemy HQ in Denver, while the rear comes from overseas.
Head-tube angle is variable depending on frame size, which compensates for reach variance and in turn improves front end control. Size small are the slackest at 66 degress, while the XL comes with a 67-degree head angle. Chainstays are a middle-of-the-road 438mm, and seat tube angle is 73.5 degrees across all four frame sizes, S-XL. Other features include internal cable routing and a threaded bottom bracket.
Frame and shock will retail for $3750. There will be two standard paint schemes, but as with all Alchemy bikes, customers can choose custom paint combinations from 15 stock colors. Availability is set for the first quarter of next year, with complete bike specs and pricing to be announced later this year.
For more information visit www.alchemybicycles.com.
This article is part of Mtbr’s coverage of the 2015 Interbike trade show in Las Vegas. For more from Interbike CLICK HERE.