Posted on April 28 2025
New for 2026, Fox has introduced a new air spring for the full travel Fox 36 chassis (140-160mm). It's nicknamed 'Glidecore', or referred to as 'NA3', being the 3rd generation of the 'Negative Air' system used by Fox since its 2015 introduction. The introduction of Glidecore marks the most significant change to Fox's air spring design since NA2 was introduced in 2017 across all of the Fox platforms. It's a handy piece of work, with some subtle but clever improvements that along with continually evolving damper, lower leg and csu designs, Fox are finding ways to make good, even better.
How does it do this?
Well, as we're riding, our forks are under constant loads, whether that be from braking, turning, jumping, sprinting, or whatever it is you typically ride over on the trail. With that considered, these loads will consistently apply loads unevenly to a fork's chassis, based on how the obstacle (or load) has been initiated. Any torsional loads on the fork will affect how the fork operates in its motion, and this can have a massive impact on the fork's performance.
Example: Your front hub is likely 110mm spacing (known as 'boost'). If your hub was 109mm as a result of manufacturing error, and you bolted the hub/wheel to your boost fork which accommodates a 110mm axle, it would apply an axial load to the fork's telescope and it would greatly stiffen up under compression. It would feel average, at best.
Hence, Fox's 2021+ 36 and 38 have a floating axle system to help deliver a perfectly aligned chassis, reducing any unnecessary stiction and performance loss as a result of hub/wheel placement in the chassis.
With the above example in mind, the obstacles encountered on the trail will inherently apply similar torsional and axial loads to a fork during normal use. The new Fox Glidecore air spring works much like a floating axle system to allow the air shaft motion to be un-impeded when the fork's chassis is being 'bent' under loads. This is done using a floating core between the air shaft and the main piston/seal heads, and the rubber bumpers enabling it to move. Ideally, any loads transferred into the fork chassis during riding, are smoothed out as much as possible via means of deflection, in this case - the air spring doing its bit to help. Whilst inflated to a rider's desired pressure setting, Glidecore air spring can handle side loads without any impact on pressure retention, or stiction.
On the right side, The oil dampers are less prone to stiction as they have far more flexibility than the air shaft side of the fork (air shaft rigidity while static is important otherwise it would potentially loose air too easily under loads). The rebound shaft of a damper, along with rebound piston glide rings and lower seal-head, usually allows for sufficient torsional loads without impeading function.
Availability:
Fox's new Glidecore air spring is available in 140mm, 150mm and 160mm options (sorry - no 170mm) is backward compatible as follows:
- 2021+ Fox 36 Performance (non-ebike)
- 2021+ Fox 36 Performance Elite (non-ebike)
- 2021+ Fox 36 Factory (non-ebike)
Weight:
Na3 Glidecore weighs 98g as pictured.
Na2 EVOL weighs 71g as pictured.
