The Chickadeehill AWK air spring kit was born in Germany. After a small production run of prototype units and plenty of forum chat and requests, a business was born. Dual positive air springs aren't new tech. Manitou has had them for years in the form of the "IRT" (Infinite Rate Tune), and Öhlins feature them as the "Ramp Up" chamber in their RXF air forks. The concept is simple: the AWK's floating piston occupies the space that a large stack of air volume spacers normally would. Increasing the pressure in the AWK chamber fine-tunes the rate that the fork's air spring ramps up near full compression. Chickadeehill offers units to fit most RockShox and Fox air-sprung forks. Prices start at €130 and move up to €330. The RockShox Lyrik/Yari unit featured here sells for €190.
AWK Dual Air Spring Details
• Dual positive air spring for Lyrik/Yari fork (other units available)
• Replaces existing top cap and volume spacers
• Weight: 64grams
• MSRP: €190 EUR
What does it do?
The idea behind a dual air spring is to make the spring curve more linear near the end-stroke A single-air-chamber fork pressurized soft enough for small bump compliance would require a stack of air volume spacers to prevent bottoming - which means it will ramp up dramatically at the end of the spring curve. Using two springs in unison can flatten out that end-stroke curve. Having two chambers also means that riders can fine tune that end-stroke air spring curve to increase or decrease bottom out resistance.
In use, as the fork compresses the pressure rises in the main chamber, when this equals the pressure of the second chamber, its piston is activated and it will start to compress. All this can provide a much more linear feel to the fork as shown in this graph provided by AWK.
The AWK air spring is said to give a 'coil-like feel' so why not just use a coil-sprung fork if that is the ride quality you desire? Well, a coil spring is heavier than air and doesn't offer the range of adjustment that screwing on a shock pump to add or subtract a few psi does to achieve the correct feel or change the balance of the bike. There are some coil conversion kits starting to appear on the market, but these do not offer the ease of adjustment, are heavier, and the coil will score the inside of the stanchions, making it difficult to create a perfect air seal should you wish to return to the standard air chamber.
At 64 grams, the weight of the AWK is comparable to the standard top cap (22grams) plus the extra 15 grams per volume spacer you'd normally choose to install.
The AWK system is easy to install. Simply release the air pressure, remove the existing top cap of your fork, and replace it with the dual-air unit. The unit can be threaded in using a 32mm top-cap socket (this can contact the fork crown, so a protecting it with a thin cloth is recommended). The direction of the Schrader valves can be adjusted with a 24mm spanner before pressurizing the system.
To inflate the system correctly, you'll need to inflate the AWK chamber (marked with the 'O'), Then inflate the fork's primary air spring to half the pressure. My preferred pressure was 60 and 120psi, which gives the fork that coil-like feel some people are looking for. After that, you are free to play with pressures to your heart's content to achieve a specific feeling.
I did have some problems losing pressure when removing the shock pump, as the valve cores protruded a little too far. That has now been changed. If yours has that issue, AWK recommend using a pump with connectors designed to prevent air loss while unscrewing.
The AWK's twin air valves protrude more than a standard top cap.
At 64 grams, it's comparable in weight to a standard top cap with 3 to 4 bottomless tokens.
The AWK kit does give a different feel to the fork; Using the 1:2 air pressure rating, as suggested, there was certainly more mid stroke support and the fork rode higher in its travel compared to my normal setup, using volume spacers at similar sag values.
The range of extra adjustment it gives you can be mind boggling and confusing, but it can also offer a performance advantage if the riders know what they want and need. As a reminder: take care to balance your spring curve with your rear suspension. Making an air fork more linear with a rear suspension that is very progressive isn't going to work out.
At €190 the kit isn't cheap - around 20% of the price of the complete fork. And, if you don't know what you are looking for, you will likely be better off tuning with volume spacers and different sag values.