The 2021 Alchemy Arktos is an intriguing mountain bike. The Arktos is sold in three different travel options, (120/135/150) but by changing out the rear shock and part of the linkage, the suspension travel of the bike can be adjusted. This makes for a versatile platform; with all the optional configurations, it’s in the running for the one bike “quiver-killer” designation.
Each travel option is paired with a longer travel fork, a configuration often referred to as long forking. The additional travel provides additional trail capacity while keeping the pedaling feel efficient on the climbs. In addition, the 135mm and 150mm travel models also support mixed wheel options should riders want to explore a reverse mullet set up – what many riders are calling the “best of both worlds”.
As a fan of mullets, I was eager to throw a leg over the Arktos 150F/135R MX model to see how it compares to other mullets I’ve tried. The folks at Alchemy were nice enough to send one over for me to ride for a few weeks and share my impressions.
The Arktos 150F/135R MX as labeled in its description features 135mm of rear suspension travel, paired with a Fox 36 fork set at 150mm of travel. The MX refers to the mixed wheel size, and the bike features a 27.5″ rear wheel and a 29″ front.
Geometry Highlights (Tested: Large, 29/27.5 MX configuration)
- Head tube angle: 64.5º
- Seat tube angle: 75.5º
- Reach: 483mm
- Effective Top tube: 625mm/24.6″
- Seat Tube length: 445mm
- Chainstay length: 437mm
- Bottom bracket height: 341mm
Specs
Available direct from Alchemy Bikes and their HQ in Colorado, the Arktos in for testing features the SRAM GX Build, which lists for $6,499. (Note, at the time of publishing this, prices appear to be rising, as the updated regular price is now labeled as $7,000) <update 10/22/21: in what seems to be a total reversal of industry trends, the Arktos 135MX is now listed at $5899>
Featuring Fox Factory Kashima suspension in the front and rear, the Fox 36 fork features 150mm of travel and the Grip 2 damper. In the rear, 135mm of suspension travel is delivered via a DPX2 Evol LV 3-Position shock.
As a Shimano fan, the Shimano XT 12SP build appears to be the sweet spot, with a full XT group and the excellent Shimano 4-piston brakes. (I run this on my personal bike and the stopping power is oh-so-sweet)
Sine Suspension
The Arktos utilizes a dual-linkage suspension platform referred to as “Sine” suspension, which is a reference to the shock rate, which as you’d expect, resembles a sine wave. According to Alchemy, SINE was designed to counter weight transfer and eliminate bobbing from pedaling while retaining tunability. I’m not going to delve into it, as you can read what Alchemy has to say about it here. Having ridden the bike for a few weeks now, my impression is the Sine Suspension does indeed pedal quite well.
The good-looking, full carbon frame has nice lines and a very clean aesthetic. It also can accommodate a full-size water bottle (I’m running a 21oz Camelbak Podium bottle; the 24oz version is a bit tall) inside the frame with mounts for a second on the bottom of the down tube.
First Impressions: MX 29″/27.5″ Mullet Configuration= Trail Fun
As the MX build is a mullet and I’ve been riding mixed-wheel rigs all year, it’s hard not to go right into the effect of the mixed wheel sizes on the handling.
First a quick disclaimer: I’m a fan of mullets and I’m already accustomed to rolling on mixed wheel sizes, with two personal bikes set up with mixed wheels. I’m fond of the MX label, which appears to trending as the official industry term for the mixed wheel configuration. It definitely sounds cooler than “mullet” and I’ve adopted it myself.
In terms of riding the MX setup, I think the biggest surprise to me what how normal the mixed wheels felt. On the other bikes I’ve ridden, the taller front end is noticeable. This could be chalked up to a first impression; regardless, the mix of wheel sizes felt good to me in terms of the handling.
The mixed wheel sizes make the bike fun in the air; 29″ back wheels are ok on mountain bike jumps but having the 27.5″ in the rear definitely makes the bike more fun and manageable on taller jumps. . I took it to the local bike park to spend some time on the mountain cross jump course and it was a good time, even with the tire pressure set for the trail. (i typically run suspension and tires stiffer for hardpack flow trails and jump lines)
Climbing is the other area where the bike stood out. It felt very efficient while pedaling, and I didn’t notice suspension movement. It does feel like there is a bit of a trade-off; the 135mm of rear-wheel travel didn’t feel like it ate up the trail as much on the rough stuff. I have been spending a bit of time on a 150mm bike though, and that is a noticeable difference in suspension travel. I also need to keep playing with the suspension settings. That said, this bike feels like it’s optimized for hard pedaling, all-day trail rides as opposed to shuttle runs; if you were going to ride bike parks and do gravity-fed riding, the 150mm travel iteration would be a more logical choice.
Those brakes tho
The price difference for the Shimano XT build is only $200. I would strongly recommend this option. After riding these excellent stoppers for the last two seasons, downgrading to the SRAM G2R in the 2-piston iteration is… uninspiring to say the least. I’m not a fan of the G2 brake in any iteration though; I’ve spent time on the four-piston version and the lack of stopping power resulted in some very bad times. (re: numerous visits to my chiropractor. (thankfully I have good insurance coverage)
The lack of stopping power really puts a damper on descending with this bike and holds it back.
Thoughts on Sizing
The size large is recommended for riders 5’9″ – 6’2″. At 5’10”, I followed the manufacturer’s recommendation and found the large fits well, though I did swap the stock stem for a slightly shorter unit.
If you haven’t ridden a contemporary trail bike in the last few years, the 483mm length of the size large may seem long. After all, it was only a few years ago when we were all riding much shorter bikes. These days I’m quite comfortable and happily riding bikes with significantly longer numbers. Two of my personal bikes feature a 475mm reach and although the large Arktos is a bit longer, I find it quite comfortable on the trail. Given the amount of suspension travel and its intended use as an all-around trail rig (as well as the size chart recommendations – the size large is recommended for riders in the 5’9″ – 6’2″ range), I figured I’d give it ago. Given the intended use of the bike, the sizing feels great.
27.5″ to 29″ Rear Wheel Conversion
I’m planning on doing some longer trail rides take advantage of the efficient pedaling of the Arktos, and plan to convert the rear wheel to 29″ to see what the 29″ iteration of the bike rides like. Alchemy was nice enough to ship a matching 29″ rear wheel and the 29″ 135mm rear wheel link, so stay tuned for an overview of the conversion and 29″ setup impressions.
The Alchemy Arktos 135 with the SRAM G2 build sells for $5,899. To get an Arktos of your own, or for more info on Alchemy Bikes, check out their website: alchemybikes.com