Suspension tuning and manufacturing company Push Industries is rolling out a coil conversion kit for Fox 36 and RockShox Pike suspension forks. The ACS-3 conversion kit is designed to enhance small-bump sensitivity and tuneability.
Seven spring weights for 125-230lb / 57-104kg riders
Fox versions for 2015-2017 Float and TALAS, available now
RockShox versions for Pike, available later this summer
$389 (UK and Australian pricing TBA)
A quick coil primer
The ACS-3 kit replaces the air springCourtesy
Coil-suspension forks are few and far between these days. Advances in air spring technology along, plus the substantial weight difference, pushed coil-sprung suspension to the wayside more than a decade ago.
But the rigors of enduro racing, a desire to maximize suspension sensitivity, and the need for reliability during multi-stage enduro events lead to the coil-sprung comeback that began in early 2016. Many professional and amateur racers have traded their air cans for coils from Fox, RockShox, Cane Creek, Öhlins and Push’s own Elevensix.
While coil shocks have made significant inroads, coil-sprung forks for trail and enduro have been slow to materialize from major manufacturers.
Push is stepping up to fill this void with a coil conversion kit for Fox 36 and RockShox Pike suspension forks.
Pros and cons of coils
Coil forks have fewer seals than air forks, so they can be suppler, providing better small-bump sensitivity and increasing traction. This does come with a tradeoff in weight, since springs weigh more than air.
Air pressure can be dialed in exactly to a rider weight. Springs, on the other hand, come in specific increments. In the case of the ACS-3 kit, seven springs are offered in 15lb increments for riders weighing between 125-230lb /57-104kg. The springs can be purchased individually for $80.
The spring curve is very different between air and coils as well. When compressed, air naturally becomes more progressive, requiring more force to move the suspension deeper into its travel. This aids in preventing a harsh bottom out. Springs follow a linear path, which may be good during the initial and mid-stroke, but can result in a lack of support as the fork nears the end of its travel, which is the reason coil forks from the days of yore used elastomers to control bottom-outs.
The ACS-3 air cartridge gives riders the ability to adjust the progressivity of the coil-sprung forkCourtesy
In an effort to provide the best of both, the ACS-3 kit uses an air cartridge to act as a tunable bump stop. This pneumatic bump stop can be adjusted from 5-50psi.
Think of this as adding or subtracting volume spacers to an air fork — more pressure will make the fork more progressive, while less pressure will make it more linear through the final third of its travel.
How it works
Push offers seven spring weights in 5lb increments to dial in the rideCourtesy
The ACS-3 kit replaces the air spring inside model year 2015-2017 Fox 36 Float and TALAS and RockShox Pike suspension forks.
What about RockShox’ harder-hitting Lyrik and Yari models, you ask? According to Push, the small inner diameter of the stanchion tubes means this upgrade won’t be an option for these forks.
While it will look like an air-sprung fork from the outside, this valve controls the progressivity of the coil spring at the fork nears the end of its travelCourtesy
Since the top cap houses the air valve used to adjust fork’s progressivity, preloading the fork must be done with a series of washers that sit on top of the spring, just underneath the top cap. In other words, you can’t set your sag by dialing in the pre-load externally. However, once sag is dialed in, it’s set and forget.
Want a deeper dive on the ACS-3? Click here for a detailed installation video.
Service while you swap
In addition to the ACS-3 kit, Push also offers a Lower Leg Service kit that includes Push’s own wiper seals, which the company claims has double the lifespan of stock wipers, enough suspension oil and grease to perform five services, along with a seal driver and topcap socket, which are manufactured at Push’s Loveland, Colorado, headquarters. This kit is available now and retails for $105. (UK and Australian pricing TBA.)