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The Beta Tests

The Beta Tests: Alchemy Arktos 135

Built to brawl beyond its travel


-135mm rear travel, 150 front
-29-inch wheels
-Carbon frame only
-Sold consumer-direct
-Modular platform can be modified for mixed wheel sizes or different travel configurations


-Remarkable small-bump compliance
-Confidence-inspiring lateral stiffness
-Modular frame will keep you from ever getting bored


-Some noticeable bob while climbing
-Travel variants come with sub-optimal geometry.







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The Arktos has finally come into its own. Beginning as a small-volume, U.S.-made one-off, the Arktos soon gained enough popularity to demand full-scale overseas production. Then it added a 29-inch version, and finally a shorter-travel 29-inch version. But today’s Arktos, which was reinvented in early 2021, offers a full range of ride experiences that could merit a full range of model names to match. The new Arktos is built off one common mainframe across its 120-, 135- and 150-millimeter versions. Each of which, we might add, is available in both 29-inch and mixed-wheel options. This is especially impressive in the 120mm configuration, given that the industry seems to believe that mixed-wheel bikes are a gravity trend. But we believe it’s got excellent applications for moderate-travel bikes. Alchemy offers aftermarket links should you want to swap your Arktos frame between any of the six configurations. All you need to provide is matching suspension and matching (or not-matching) wheels.

As with other brands like Guerrilla Gravity who have gone that same route, this brings some compromises, like longer-travel models having slacker seat tube angles and shorter-travel versions having longer reach measurements, but the 135mm model is right there in the sweet spot, so that’s the one we brought in.

Also common among all the Arktos models is Alchemy’s Sine suspension design. It takes its name from the sine-wave shape of the leverage curve. It allows the shock to be more sensitive in the early bits of the travel to offer optimal small-bump compliance, some supportive ramp up through the mid-stroke, and then aim for sensitivity again near the late stroke to mitigate the natural ramp-up of the shock, all the while still leaving just enough bottom-out resistance. When we put it that way, it’s no wonder they named it after a geometry term.

And it works. It works well, especially in conjunction with the benefits of a bike with the travel of a trail bike but the front and rear triangle of an enduro bike. In the spirit of modern mountain bikes, the Arktos 135 felt as stout to us as some of the enduro bikes we rode. That early-stroke sensitivity stood out for each of our testers, and allowed us to push the Arktos 135 beyond what a bike of its travel ought to be capable of. 

Evil’s DELTA link takes essentially the opposite approach to its S-shaped leverage curve, starting at its very supplest and ramping up to a more level mid-stroke before ramping up its bottom-out resistance, air-spring spikes be damned. But Alchemy takes the shock’s natural progressivity into account, and its initially regressive curve makes for a deeper small-bump sensitivity. The mid-stroke on both platforms is supportive, which played to the strengths of the Arktos 135’s ability to encourage us to stay active and engaged with how we interact with the trail. “Playful” is the short-hand version of that sensation, but that tends to imply some lack of safety. The Arktos’ ability to keep us from getting knocked off-line was rather liberating.  

And this approach to small-bump sensitivity makes sense given that, on the descents, there is naturally less weight on the rear wheel. It also suits the way we’re re-learning how to position ourselves on our bikes as they continue to lengthen. The generous amount of extra sensitivity allows the rear wheel to track the ground like a longer-travel bike and, in turn, we could ride it like a longer-travel bike. 

This all becomes less optimal on the climbs, though. Perhaps it’s because our testers had such high hopes for what Sine Suspension could achieve, but there was a nagging amount of bob while climbing, both while soft-pedaling and mashing. Nothing that a little blue lever couldn’t fix, but we found this is not the pedal-focused platform that a VPP or Switch Infinity is. That’s not to say the geometry isn’t well suited for big climbs. One tester who is already used to relying on lockouts for the first half of most loops had no complaints. And on undulating terrain, any efficiency loss was negligible enough to be worth the above-mentioned benefits of the Sine platform.

And this all comes in a package that is as refined as you’d want a bike with such a boutique name to be. There’s the essentially limitless seatpost insertion, tube-in-tube cable routing, and an in-triangle bottle on all sizes. Those sizes do stop at medium, though, which is a bummer on a bike with mixed-wheel capability, which is a feature well suited for shorter riders. But it’s a feature that far too few brands offer, despite it taking little more than some different hardware. The modular frame concept and nerdy leverage curve are the stuff of a by-riders for-riders brand, which has been Alchemy’s thing ever since the first Arktos.

Studio photos: Ryan Palmer

Action photos: Paris Gore