Fox has a long history in the world of shocks in both mountain biking and motocross, but their first mountain bike suspension fork was launched back in 2001. It proved a huge hit and this 32 chassis was quickly followed by the burly 36, downhill 40 and then the trail 34 and super enduro 38 forks, all available in a number of specs to suit different budgets.
Our guide will run you through the current Fox front fork range, including all the different models, the specifications available for each of those and what all means, in order to help you find which one is best for you and your budget.
[Updated 7th April 2020]
2021 Fox fork range
All Fox forks follow the same naming convention, where a number tells you the upper leg diameter in millimetres, which in turn gives you an idea of the end-user the fork is suitable for. Roughly summed up, the 32 series of forks are made for cross-country and light trail use, the 34 forks are meant for all-around trail use, the 36 is for heavy-duty trail/all-mountain use, the 38 is for enduro riding and racing while the dual crown 40 is made for downhill and extreme gravity riding. All of Fox's aftermarket forks use air springs.
In addition to these base chassis designs, here are a number of different specification levels for each of them, which is why the Fox fork range adds up to around 160 different models...
Factory Series forks
This is the highest level of Fox fork and is priced accordingly. All these models have high-end FIT4 and FIT GRIP 2 dampers and use the distinctive golden 'Kashima' coating on the upper legs to reduce friction and increase wear life. The Kashima treatment creates microscopic pores on the upper legs that retain lubricating oil as the forks cycles through the travel, making it much slippier.
Performance Elite forks
This is the middle of the Fox forks range and while they share the same high-end damper technologies as the Factory forks with FIT4 and FIT GRIP2 options, the upper legs just have a black anodised finish rather than the Kashima coat.
This is the entry-level specification of Fox forks that are available on the aftermarket. Different, less complicated FIT GRIP dampers are used and the upper legs are again black anodised. The lower legs are the same as the higher end forks, however.
This is an original equipment (OEM) only level of fork that you'll on see specced on complete bikes. The Rhythm forks have a slightly less adjustable GRIP damper and the lower legs are cast from a heavier but more affordable grade of aluminium to keep costs down.
Step Cast models
Fox has introduced 'Step-Cast' versions of both the 32 and 34 series, which use a narrower stance plus slimmed down, stepped lower legs to help reduce weight. They're pitched at the lightweight cross-country and lightweight trail markets respectively.
There are also E-bike specific versions of the Fox 34 and Fox 36 series. These use thicker-walled upper legs to increase stiffness and so deal better with the extra bulk of an electric bike. The trade-off is that they're heavier.
The Fox 32 Step-Cast is available for 650b and 29" wheel sizes in Factory and Performance spec, all having 100mm of air-sprung travel, a tapered steerer and standard or Boost hub spacing with a 15mm through axle.
Factory-level forks get a sealed FIT4 cartridge damper which has a three-position compression adjuster with a low-speed fine-tuning adjuster in the open mode, plus rebound damping adjustment. There is also a two-position bar-mounted lockout available.
Performance forks use a GRIP cartridge damper which offers three-position compression adjustment.
There is also a special version of the 32 Step-Cast called the Fox Step-Cast AX or Adventure Cross. It's specially modified to work on gravel bikes with 700c or 650b wheels and has just 40mm of travel from a specially converted spring. It uses a FIT4 damper.
The Fox 32 Factory fork is available in both 29" and 650b wheels with 120mm of travel, a 15mm through-axle and a tapered steerer. The FIT4 damper and Float air spring are used, though there is the option of a two-position bar-mounted remote instead of the top cap mounted adjustments the FIT4 has as standard.
The Fox 32 Performance fork is available in 26", 650b and 29" wheel sizes, all with a three-position GRIP damper. The 26" fork has 100mm, 120mm and 140mm travel options with either an open 9mm or bolt-through 15mm axle, plus straight 1.125" or tapered steerer. The 650b fork only comes with 100mm travel and a 9mm open axle and a tapered steerer, while the 29" fork comes in 100mm with a 9mm dropout or 120mm with a 15mm through-axle.
Again, there is a Step-Cast range of 34 forks, which start with the 34 Step-Cast Factory. Only available in the 29" wheel size, it comes with 100 and120mm travel options and 44mm, and 51mm offsets with Boost hub spacing and a tapered steerer. As always, it's got Kashima coated upper legs and uses the FIT4 damper with remote option, though both this and the air spring have a dedicated tune. This one also gets a tuneable negative air spring and space for up to a 2.4" tyre.
There's also the 34 Step-Cast Performance fork, which only comes at a 29" wheeled, Boost spaced, tapered steerer 120mm travel model with GRIP three-position damper.
The standard chassis range is topped by the 34 Factory which comes with the FIT4 three-position damper for 2022. Like its Step-Cast sibling it only comes in a 29" wheel option but unlike the Step-Cast model, there are 130mm and 140mm travel options. A tapered steerer is the only option but you can get it in Boost and non-Boost spacing for a 15mm axle. This model can also fit up to a 2.6" tyre,
The 34 Performance Elite does without the Kashima coating but retains the FIT4 damper. It only comes in 29" options and with 130mm of travel.
The 34 Performance uses a three-position GRIP damper and it's only available in the 29" wheelsize. It gets 140mm of travel and space for up to a 2.6" tyre.
When it comes to e-MTB specific models, there's only one. The 34 E-Bike Performance gets a GRIP damper and black anodised upper legs made from thicker-walled tubing than the conventional range. It only comes in 120mm travel with Boost spacing, whether in 650b or 29er form.
Fox's 36 range was overhauled for 2021, moving it to more of a long-travel trail bike fork as the 38 picks up the enduro duties, with travel being capped at 160mm. New features include air bleeders on the lower legs, new internal channels to reduce pressure build-up in the lowers, a floating axle and an updated version of the EVOL air spring and FIT GRIP2 damper.
The 36 lineup is topped by the Fox 36 Factory which is available for 26", 650b and 29" wheels and only comes with an EVOL Float air spring.
The 650b fork comes in 150mm and 160mm travel options, with either an updated version of the four-way adjustable FIT GRIP2 damper for £1,199 or the FIT4 damper for £1,139. It's tapered steerer with Boost spacing only and you can have 37mm or 44mm offsets.
The 29" fork comes in 150mm travel options with a FIT4 for £1,139 or with a FIT GRIP2 in 150mm and 160mm for £1,199. Offset options are 44mm and 51mm.
When it comes to 26" wheeled versions, these use a different chassis based on an older version of the 36. There's a dirt jump bike specific model called the 36 Factory 831 26 which only comes in 100mm travel, plus a trail model in 160mm and 180mm travel options. Both have a FIT GRIP2 damper with a non-boost 15mm axle that can be converted to 20mm. There are straight or tapered steerer options. RRP is £1,179.
Fox 36 Performance Elite forks only use a FIT GRIP2 damper and both are 650b and 29" forks are only in 160mm travel. You can only get Boost spacing and a tapered steerer in these forks. RRP is £1,099.
The 36 E-Bike Factory fork is available as a 29" fork with 160mm of travel (though of course 650b Plus tyres fit into this model) with a FIT GRIP2 or FIT4 damper, Boost spacing and tapered steerer and your pick of 44mm or 51mm offset. It also comes in 650b with 140mm, 160mm or 180mm travel options.
The 36 E-Bike Performance fork only comes in a Boost 29" version with 160mm of travel but has black anodised upper legs and uses a three-position GRIP damper. Offsets are 44mm or 51mm.
The new for 2021 Fox 38 fork is designed as a hard-hitting, long-travel enduro fork, replacing the longer travel variants of the 36. It gets air bleeders on the lower legs, new internal channels to reduce pressure build-up in the lowers and an updated version of the EVOL air spring and FIT GRIP2 damper. It also uses a steerer tube that has an oval internal profile to help beef up a highly stressed area.
The range-topper is the Kashima coated Fox 38 Factory, which is only available with a FIT GRIP2 damper and 160mm, 170mm or 180mm of travel. The 650b forks have offset options of 37mm or 44mm, while the 29" forks come in 44mm or 51mm. RRP is £1,299.
The Fox 38 Performance Elite only comes in 170mm travel with a FIT GRIP2 damper. Both the 650b fork and the 29" fork have an offset of 44mm and cost £1,199.
The Fox 38 Performance only comes in 170mm travel with a GRIP damper. Both the 650b fork and the 29" fork have an offset of 44mm and cost £1,049.
There's also an e-bike specific version, the Kashima coated Fox 38 E-Bike Factory. It's only available as a 180mm travel, FIT GRIP2, 29" fork with 44mm offset and costs £1,299.
When it comes to aftermarket options, you can only buy a Kashima coated, air-sprung Fox 40 Factory, but there are a trio of wheel size options, with 26", 650b and 29" options. All have 203mm of travel, FIT GRIP2 dampers and straight 1.125" steerers. The 26' and 650b forks have a 20mm through axle, but the 29er - now known as the Fox 40 Factory - gets a 20mm Boost axle.
The 40 range had a makeover for 2021 with similar air channels in the lowers as the 36 and 38 forks, plus similar chassis revisions.
There are also Fox 40 Performance level forks, but these are original equipment for manufacturers only.
Fox has a number of technologies that they use exclusively on their forks.
Float EVOL air spring: This is Fox's air spring system used across the entire range. The EVOL part stands for 'Extra VOLume' and indicates that it has a larger negative air spring than previous Float designs in order to make . the initial part of the travel more linear.
FIT 4 damper: This is one of Fox's premium cartridge dampers. The name stands for 'Fox Isolated Technology. It has a three-position compression adjust via the blue lever on the top car with fine-tuning adjustment in the open mode via the black knob, or there is a two-position remote lockout available. It also has a rebound adjustment at the bottom of the leg. It uses a sealed design with a rubber bladder to compensate for displaced oil as the damper cycles through the travel.
FIT GRIP damper: This is the damper fitted to more affordable models in the Fox fork range. It has a three-position compression damping adjustment from a blue lever at the top of the leg and a rebound at the bottom. It is a semi-sealed cartridge that uses a sprung piston to compensate for displaced oil, with a feature that allows it to bleed excess oil as needed.
FIT GRIP2 damper: This is a premium damper seen on Fox's gravity focussed forks. It has the same basic architecture as the FIT GRIP damper - namely a sprung piston - but it has much more adjustment, with both high and low-speed compression damping adjustment and independent high and low-speed rebound damping on offer too. It uses something called Variable Valve Control adjust the high-speed rebound damping, which alters valve flex rather than preload, which Fox say "provides the same effect as revalving high-speed rebound but without the need for damper disassembly". It also has a different mid valve, plus various friction reducing treatments over the standard GRIP damper.
Kabolt axle: This is an axle that can be used to replace the standard flip-lever 15mm through axle found on Fox forks. It's lighter than standard but requires a 6mm Allen key to undo.
Kashima Coat: This is a hard anodising surface treatment created by Miyaka Company of Japan. It consists of "lubricating molybdenum disulfide deposited via electrical induction into the billions of micro-pores on the surface of hard-anodized aluminium for better lubrication and less abrasion and wear."
Lower leg channels: These are seen on the new 36, 38 and 40 lower legs and are an air channel that increases the amount of air volume in the lower leg of the fork. As a fork compresses, the air that's trapped inside the bottom of the lower leg is squashed and this acts like another air spring to the main one, giving a resistance to bottoming-out that the rider can't tune, making it hard to get full travel.
This greater volume provides less ramp-up effect, meaning the air spring can operate without this interference. It's also allowed them to use a greater volume of lubricating oil in the lower and provides a pathway for that oil to get higher up into the bushings and seals, meaning your fork should stay smoother for longer.
Volume spacers: All Fox Shox forks allow the user to control how progressive the ending stroke of the fork is by using volume spacers. These require you to undo the top cap of the fork's air spring side leg and then add or remove clip-on spacers. Adding more increase the resistance to bottoming out, while removing them does the opposite. The volume spacers are specific to fork models and colour coded to match. The thicker legs on E-Bike specific forks require you to use a spacer from the fork below it; a 36 E-Bike fork would use the spacer for a standard 34 fork, not a standard 36 fork.
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