Fox added the 38 to their lineup for 2021, supplanting the 36 as their biggest single-crown fork. As the name suggests, it has 38mm-diameter stanchions, and is designed to be an option for riders looking for a stiffer chassis with greater steering precision and improved tracking through rough terrain. That added stiffness comes at a weight penalty of around 270 g, depending on the exact configuration. The difference in stiffness is significant, particularly for bigger riders, and those tending to charge harder in steeper, rougher terrain. Compared to the forks here with smaller stanchions, the 38 tracks noticeably better, is more precise in holding a line, and is stiffer fore-aft under hard braking and the like.
That’s not to say that everyone should be abandoning the 36 in favor of the 38 though — far from it. The 38 is substantially heavier, and for more varied Trail-bike use, the 36 is going to be plenty of fork for most people.
In terms of design, the 38 shares a great deal in common with the revised 2021 Fox 36. The overall design language is nearly identical, and the lowers share the same set of features that the newest 36 received, including the air channels, air bleed ports, and floating axle. Check out our full review of the 38 for more details on that.
The 38 shares the updated Grip2 VVC and base Grip dampers with the 36, but in keeping with its gravity-oriented focus, the Fit4 option is dropped for the 38. There’s also no 38 Rhythm available as of publishing this article, paring the list of versions down to Factory, Performance Elite, and Performance.
As with the 36, the Factory and Performance Elite versions use the same Grip2 damper, and differ only in terms of finish, both on the lowers and on the stanchions. The 38 Performance shares its chassis with the 38 Performance Elite, but gets the base Grip damper with adjustable low-speed compression and adjustable rebound, as compared to the Grip2’s adjustable high- and low-speed compression and high- and low-speed rebound.
The air spring of the 38 is in some ways similar to that of the 36, but has one notable difference: instead of using the inside of the stanchion for the air piston to ride on, the 38 adds a separate tube inside of the stanchion for this purpose. Mostly, this allows Fox to tune the progression of the fork a bit more — very long-travel, air-sprung, single-crown forks tend to be quite progressive, due to what basically boils down to packaging constraints. The extra tube in the 38’s air spring gets around this, allowing for a wider range of progression adjustment (again via volume spacers) and also might help a little bit with binding in the air spring due to chassis flex, as an added benefit.
As far as suspension performance goes, the 38 feels broadly similar to the 36 (when comparing both with the Grip2 damper). The difference in chassis stiffness, and the added precision that brings to the 38, is by far the greatest point of differentiation between the two. If anything, the 38 is a tiny bit more supple on smaller bumps, with a touch better small-bump compliance than the 36, but the difference is subtle. On the flip side, the 38 has less of a tendency to feel harsh and spiky though choppy, high-speed impacts (such as braking bumps), or when cornering. The stiffer chassis binding up less is likely a big part of the reason why. As with the 36, the latest Grip2 VVC damper in the 38 does an uncommonly good job of mitigating the harsh, spiky behavior that can be felt when running the high-speed compression adjuster cranked up on many other forks, but also has a relatively light high-speed compression tune. Riders accustomed to running their high-speed compression adjusters very firm on most forks might be wishing for a stiffer setting out of the 38.
The comparison between the RockShox ZEB and the Fox 38 is also fairly similar to the Lyrik vs. 36 matchup. The ZEB is especially notable for how thoroughly it mutes small chatter — if you’re looking for a fork to simply make small bumps disappear, it’s outstanding. I feel that the 38 delivers a bit more feedback to the rider and is a bit more supportive, but Noah has a slightly different take here.
Noah Bodman (5’9”, 155 lb / 175 cm, 70 kg): I found the 38 to be better at ironing out the trail while retaining a “lively” feel, whereas the Zeb is decidedly more muted. The differences in opinion are almost certainly related to setup, and the 38 is quite touchy with regard to air pressure (see my full review). The 38 also has a fairly narrow range of compression damping adjustments (plenty of clicks, but they don’t do that much), which means it might be harder for a rider to achieve a particular “feel.”