A new beefed-up, single crown enduro fork from Fox has been spotted at the final round of the EWS under riders Martin Maes and Richie Rude. It's likely to be the long-rumoured 2021 Fox 38, a long-travel, stiffer version of the 36 built for heavy-duty enduro racing. Here's everything we know about it.
We've heard rumours swirling about Fox creating a long travel riposte to RockShox Lyrik lineup in recent months but understandably no-one has been willing to go on the record with any details. This appearance at the Zermatt round of the Enduro World Series means that Fox is teasing the new design to the public - if they wanted to purely test, they'd do it behind closed doors.
It's slightly but noticeably burlier in all the 'spy' shots that have emerged so far on Instagram and the like. We're pretty confident will be called the 38 because it sits between the current 36 single crown enduro fork and the downhill, dual crown 40 - and because the upper legs will be 38mm in diameter. This is the most logical way for Fox to progress anyway - Fox 39 or 37 doesn't sit quite as nicely.
The forks used by Maes and Rude both were stickered as 36 units but had Fox's RAD (Racing Application Development) logo on them, which has been used on prototype - more accurately pre-production - forks in the past.
These RAD forks also seem to use the same FIT GRIP2 damper seen on the rest of Fox's high-end range. We've no reason to think they'd change this for the 38 - it's a relatively new design and works well, with four-way adjustable damping for high and low-speed rebound and compression.
Detail photos show that it has the air bleed valves seen on the 40 forks on the back of the legs - these allow you to vent any excess pressure that builds up in the lowers as air pressure changes or is 'swallowed' by seals, reducing performance.
Why go to a 38mm chassis?
The big thing here is stiffness. Simple physics tells us that even a small increase in diameter allows a stiffer tube for a given weight. RockShox' Lyrik forks use the same 35mm legs as their lighter-duty Pike fork, but with thicker lower castings and thicker walled tubes for the upper legs, which means a weight penalty for that extra stiffness.
It's likely that moving to a 38mm leg will allow Fox to provide a stiff chassis at longer travel settings - 180mm and upwards, possibly - without hugely increased weight. A stiffer chassis means less flex, less bushing bind and superior suspension performance.
The larger diameter lower leg also means that the air spring on the fork can have a larger negative chamber, which reduces breakaway friction. RockShox achieved this in their Debonair spring on the Lyrik via using the volume inside the air shaft itself to add to the negative chamber, but going to a larger diameter leg means there would be much more volume to play with.
What are the downsides of a 38mm chassis?
It's not all plain sailing when you go to a larger diameter leg diameter. Most of the issues arise from the fact that a larger diameter fork leg needs larger diameter seals and bushings, both of which will increase friction as there's more surface area rubbing against the fork leg. More friction in your fork is a bad thing, for obvious reasons.
It's interesting neither of these RAD forks get the golden Kashima coating seen on Factory spec Fox forks - maybe Fox was hoping that black would be slimming...
The other thing isn't strictly related to the diameter of the chassis but to any long travel single crown fork - make the thing stiffer and you're just putting that bending load elsewhere, with the crown being a particularly highly stressed point. That's why 200mm travel forks have traditionally always been dual crown - it's a better engineering solution to making something stiff and strong, though obviously steering lock is lost. It'll be interesting to see just how much lighter the 38 is than a 40 regardless.
What does Fox say?
We spoke to Chris Trojer from Fox Europe and he said: "In an effort to continually develop highly-advanced suspension products, Fox constantly tests prototype components in the field under the world’s best racers. Some of these components – or parts of them – eventually make it into production, many of them do not. Testing in real-world environments is a critical part of how we determine what works best – not only for our professional athletes but ultimately for every rider who puts their trust in FOX products. This field testing protocol is part of our proven and longstanding RAD (Racing Application Development) program."
That's a neither confirm nor deny, in case you were wondering.
What will happen to the 36 fork range?
It's a very popular fork line for original equipment and aftermarket, so the 36 is unlikely to get totally replaced by the 38 except at longer travels. However, looking at the rest of Fox's lineup can lead to a fairly uneducated guess that there might be some kind of middle in the lineup to split the difference between the 34 and 36 range.
The best way to do that would be to introduce a Stepcast chassis version of the 36, much like the existing Stepcast 32 and 34 which sit at a lighter weight and lower travel than the full-blown 32 and 34 models.
When will the Fox 38 be available?
Fox usually allows the prototype units to be seen a year or so in advance of the actual launch based on our experience of the Stepcast 32 and the 29er version of the Fox 40, so we'd guess that these are 2021 model year products that'll get launched in August-September 2020 thanks to the crazy world of bike industry years.
We'll be updating this as and when we get more information, but it's interesting times in suspension world - will this be able to depose the RockShox Lyrik from enduro rider and racer's hearts and minds? We'll see...
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