Built for the rowdiest XC tracks, and lightweight shredding, the minimal new Fox 34 SL comes in a sub 1,500g package.
Fox has a new lightweight 34 SL fork in town, and it’s built for aggressive riding. In a departure from the previous 34, out goes the narrow-shouldered Step-Cast chassis in favour of a broader, burlier structure built, according to Fox, for the ‘most technical World Cup XC courses, and demanding downcountry riding’.
The lower legs aren’t as distinctive as the 34 SC, but the new Fox 34 SL still has an eye-catching brace and crown, along with a more capable build.
Fox 34 SL need to know
- Max 130mm travel (110, 120, 130mm options)
- Full width chassis
- Larger volume air spring
- Generatively designed arch and crown
- 17% torsionally stiffer (claimed) than 34 SC
- 20mm extra bushing overlap
- Bypass channels moved to inner surface of legs(improves stiffness)
- Claimed weight 1,475g (previous 34 SC weight 1,422g)
Wider, stiffer chassis
Fox’s 34 Step-Cast used a staggered lower leg casting that saved weight by narrowing the width of the fork while keeping the dropouts wide enough to accommodate a Boost hub. This had its compromises though, limiting tyre size, reducing torsional stiffness, and shortening the space available for the air spring.
Fox’s new 34 SL switches to a straight-leg design in its quest to mix with the best suspension forks, gaining broader shoulders at the crown that increases the resistance to twisting by a claimed 17%. A significant amount that makes the new 34 SL more appropriate for the tougher courses appearing on the World Cup circuit, and for hard-charging riders looking to shred fun trails on the best down-country bikes.
The generative design process has resulted in a swoopy, organic shape for the brace.
A.I. assisted, generatively-designed arch and crown
Increasing the stance isn’t the only way Fox has made the new 34 SL more appropriate for shredding. Both the lower leg arch and the crown have been designed with the help of a generative tool first used by Fox on the 32 Step-Cast. In this process, the engineers decide on a number of weight and stiffness parameters, fix a volume that the part must fit, and let an A.I. powered design program comes up with a number of potential solutions. These are then whittled down and refined to reach the final design. While not as whacky as the reverse bird’s nest of the 32 SC, the work of the generative design tool is plain to see on the 34 SL in the intricate cut-outs of the wraparound arch and organic shaping of the crown.
Which is also reflected in the hollowed and scooped crown design. Which is also anodised to save weight compared to paint.
20% more bushing overlap
The third and final tool in the 34 SL’s muscular makeover is inside the legs. Bushings have been placed 20mm further apart to ensure smooth running and help prevent binding under cornering and braking loads. Keeping the friction between the upper and lower legs to a minimum, and ensuring they run in parallel, is key to maximising grip when turning and braking on descents. That 20mm represents an increase of 20% over the previous fork. One small but important detail that has also improved the fork’s stiffness front to back is moving the bypass air channels from the rear of the lower legs to the inside. This adds more material and gives more support to the bearings at the point where it’s needed most.
Removing the step has allowed Fox to widen the bushings, as well as increase the air-spring volume.
Class-leading weight
Check the figures and you’ll see the new 34 SL is heavier than its predecessor by 53g, but considering the improvements to the chassis build, that seems like a remarkable achievement. Fox has left no stone unturned in the quest to keep the mass to a minimum, even resorting to double-butting the damper side stanchion (-9g), and scaling back the flange diameter on the Kabolt SL axle to save 12g. All that effort means the 34 SL is still lighter than RockShox’s Sid Ultimate, even though it has 10mm extra travel. True, the Sid does use larger diameter upper tubes (35mm Vs. 34mm) but 1,475g is still over 30g lighter than the Sid Ultimate I tested a few years ago.
That new crown is a wild mix of ribs and scallops.
Bigger air spring volume
Keeping the lowers a constant diameter to the dropout has opened up more space for the air-spring, allowing the new 34 SL more negative volume, which improves the initial sensitivity and grip, as well as extending the max travel by 10mm. In the right leg is the Grip SL damper, with its pressure-balanced internals and larger base valve with more shims for better control. Of course, being designed for XC racing as much as down-country, it can be paired with Fox’s revised Twin Stick remote lock-out for rapid starts and finish line sprints.
Combine the 34 SL with the Twin Stick remote, Float SL LV shock, and Transfer SL dropper, and Fox says you have the lightest XC package on the market, some 333g lighter than its nearest competitor.
Moving the bypass channels to the inner leg helps reinforce the most-stressed area of the lowers.
Fox 34 SL prices
There are three versions of the Fox 34 SL fork available.
- Fox 34 SL Factory (Grip SL or Grip X) – £1,259
- Fox 34 SL Performance Elite (Grip SL) – £1,119
- Fox 34 SL Performance (Grip three-position) – £749
- Fox Twin Stick dual remote lever – £184.95