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Product Review

Riding the 2021 Fox 40 Fork

Words Tim Coleman
Photos Tim Coleman
Date Dec 3, 2020
Reading time

I was recently asked to review the new Fox 40 for model year 2021. Initially I declined because I only had a 29er downhill bike, and I'd be after a Fox 49 to review. Except I'd be wrong, because there is no longer a Fox 49 for 2021. To stay consistent with the rest of the fork naming in the Fox lineup, the new 2021 Fox 40 has options for both 27.5" and 29" wheels, and the 49 name has been dropped. After this news I was rather excited to try out the new Fox 40 ... with a 29er wheel!

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The Fox 40 was mounted up to a new Canyon Sender for this review. A rather pretty combination.

Maybe it's just me, but I feel like the Fox 49 was just released. How much could have possibly changed to warrant this review of the new Fox 40? As it turns out, quite a lot. Fox has made updates to the air spring, the damper and the lowers. So pretty much everything.

Key Features:

Intended Use; Downhill

Wheel size; 27.5" or 29"

Spring; EVOL Air Spring

Damper; Grip 2 with VVC

External Adjustments; High and Low Speed Compression, High and Low Speed Rebound

Travel; 203 mm

Offset; 48 mm (27.5" wheel) / 52 mm (29" wheel)

Axle; Floating 20 mm Thru-Axle x 110 Boost

Colours; Black, Orange or Battleship

Starting Weight; 2816 grams

MSRP; $2,310 CDN or $1,749 USD

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For 2021 the Fox 40 is available in the Gucci Factory spec only with Kashima Coat uppers and Grip 2 VVC damper.

Grip 2 VVC

The damper in the latest Fox forks is based on the fantastic Grip 2. VVC is Fox's latest improvement to the Grip 2 high-speed circuits, which allow for external fine-tuning of said circuits. Fox claims that GRIP2 VVC achieves with the twist of a knob what typically requires the time consuming and complicated task of completely disassembling and reassembling the fork.This video gives some good additional info on how and why Fox has implemented VVC. Externally adjustable low-speed compression and rebound, each have 16 clicks while externally adjustable high-speed compression and rebound twist to 8 clicks apiece.

EVOL Air Spring

EVOL technology increases negative air spring volume, which Fox claims will optimize small bump sensitivity. Fox says this is because EVOL’s linear spring curve delivers plushness off the top, extra mid-stroke support, and more tunable bottom-out progression.

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Standard fare Fox 40 on the top with familiar air spring pressure and volume change on the left. External high and low speed compression adjustments on the right. The Limited Edition Fox 40 comes with the black caps.

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Handy suggested air pressure and rebound setting chart on the bottom of the right leg. This isn't in the most convenient place to read though. Imagine being crouched over in the lift line squinting at the bottom of the fork with Jerry's asking if you need any help. "Thanks bro, I got this". Close by, at the bottom of the right leg, you'll find the high and low speed rebound adjusters.

Lower Leg Improvements:

The arches on all the new Fox forks have been shifted forward. The purpose is to clear the growing head tubes on many modern bikes when the fork is at bottom out. The Canyon Sender I'm riding is a good example as it has 16 mm of reach adjustment built into the head tube. With the reach adjustment in the shortest setting there is quite a lot of headtube in front of the steerer tube. Some have commented that the arches on the new Fox forks are ugly. But when mounted up I don't mind the look and I understand why Fox has made the change. Beyond the arch jutting forward, Fox claims they've been able to optimize the shape of the arch to ensure maximum stiffness with the smallest amount of material.

The floating axle found in both the new 36 an 38 has also been implemented in the Fox 40 allowing the fork's wheel mounting surface to precisely match the front hub flange spacing. Fox claims this helps prevent any bending and side loading of the fork lowers, which should reduce unwanted friction between the upper and lower fork legs. If used properly the floating axle should provide smoother suspension movement throughout the fork’s travel, improving sensitivity and overall ride quality.

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Fox has added plenty of detail on the revised arch to optimize the strength / stiffness to weight of the new Fox 40 Lowers.

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Post mount for 200 mm rotors is standard, which makes sense on a DH fork.

Fox has revised the lower leg bleeders to allow for easy atmospheric pressure equalization. Pressure build-up in the lower legs will add preload to the suspension, and make achieving full travel more difficult. Being able to regularly vent the lowers should ensure the best fork performance and small bump sensitivity.

In order for the air to get to the air bleeders, Fox has added lower leg channels in the new Fox 40, which also increase the air volume in the lower leg. This increase in volume reduces pressure build in the lowers at bottom out, which allows for more control of the air spring ramp by using tokens in the air spring. Another benefit of these channels is that the lower leg bath oil is more easily circulated to the upper reaches of the lower legs, which should reduce stiction.

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The two screw holes in the arch are used in conjunction with the air bleeders to mount the integrated Mud Guard.

Ride Impressions:

I've had the fork a few months now, and been able to ride the Fox 40 through a wide variety of trails and conditions. I've played around with a variety of settings, and settled on the following:

My 2021 Fox Fork Setup:

Air Pressure: 87 psi

Tokens: 4

High-speed compression: 4 clicks out (out of 8 clicks)

Low-speed compression: 7 clicks out (out of 16 clicks)

High-speed rebound: 5 clicks out (out of 8 clicks)

Low-speed rebound: 5 clicks out (out of 16 clicks)

On my first few rides I found the Fox 40 a bit harsh. I was moving around on settings, but it just never seemed to adsorb the high speed bumps like the Fox 49 I rode on the V10 last year. After the first few rides however, I felt like the fork performance improved. It could be that I got the settings to a place where I really liked them, but I feel like there was a short break in period on the new Fox 40.

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The Fox 40 was ridden through a wide variety of conditions from warm and sunny, to cold and wet. This day was not warm. Photo by: Anthony Boussetta.

Performance-wise, I expected the new Grip2 VVC damper to be a significant step forward but I didn't notice a massive improvement over the standard Grip2. Again, that's not a bad thing, I thought the Grip2 damper in the Fox 49 was pretty much perfect, and the Grip2 VVC is just as good. I can confirm that the Grip2 VVC produces a lot less compression damping with the adjusters closed than the Grip2 damper. However the Grip2 VVC and Grip2 at my desired settings feel very similar in damper profile. Furthermore I still had ample adjustment range on the Grip2 VVC, so I could have run more compression damping if I wanted. It looks like Fox has significantly narrowed down the adjustment range on the high speed compression circuit with VVC. So while I think the Grip2 VVC is just as good as the Grip2, folks looking for an ultra-firm high-speed compression tune may run into limitations with the Grip2 VVC damper. As for the external adjustments, all seemed to make a noticeable and predictable change. Ultimately I was able to get the Fox 40 to perform exactly to my taste. Good low speed support, with relatively open high speed circuits to build traction and save my hands.

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It was crispy this day, which meant having to run the damper adjustments open a click or two to compensate for the cold. Photo by: Anthony Boussetta.

Now that it's broken in and setup correctly I love how the Fox 40 performs on trail. The fork provides great support through low-speed events, building superb traction through braking and cornering. The firm support and stiff chassis do a great job of communicating what's happening with the front tire through to the rider. All the small changes to address friction add up to make a structurally stiff chassis, but with no stiction or binding anywhere in the travel. With the air bleeders regularly equalized, the Fox 40 always feels buttery and frictionless. The best bit is that you can have all that support, but without any harshness through the travel. The high speed compression circuit is incredibly effective at adsorbing rough braking bumps and bomb holes. This is heavenly for someone like myself (an office worker with soft hands) where I can have the support and control, but with less arm pump. There were a couple situations where I jumped into a section and saw I was heading for a nasty looking hole going way too fast. I braced for impact, making that cringey face, body ready for the horrific impac, hands clinging to the bars, waiting for an almighty clap. Then, OMNOM, the 40 would just miraculously eat the nasty hole. From what should have been a horror impact event through the fork, the 40 would transmit only a minimal amount of force.

Another trait I like about the Fox 40 is how well it performs over a wide variety of terrain. Some forks need a different setup whether on a steep gnarly trail, or a faster low angle one. With the 40, once I got my settings right I barely touched them. Regardless of the type of trail the Fox 40 provided excellent traction and support. I have however noticed the Grip2 dampers are a little temperature sensitive. All suspension will run a bit slower when it's cold out, but I feel I notice it more with the Grip2 dampers than on some other forks. This is easy to rectify by removing a click or two of damping depending on how cold it is. I personally email myself my suspension settings when I'm happy with the setup, and whenever I make any changes. This way I know what to change back when the temperatures warm up.

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The Fox 40 was ridden in some wet, cold and sloppy conditions regularly. No issues to date.

After a couple months riding the new 2021 Fox 40 I can say this an excellent fork. It's a top-shelf product, that isn't cheap. Thankfully the price of admission means there is little to complain about. The air spring is smooth, and can be tuned to ramp to your taste. The new Grip2 VVC damper is good as well, unless you're looking for loads of high speed compression damping. The fork felt buttery and frictionless over the test period. Through a wide range of terrain the Fox 40 proved stiff and precise, providing excellent support, but also suppleness over square edges and fast brake bumps.

My only critiques of the Fox 40 are that it isn't a big step forward performance-wise over the already excellent Fox 49, and the damper may need adjusting when it's cold. On the plus side I like the new air bleeders and like how the new Mud Guard interfaces with the fork. I also like the Battleship colour, especially on this test mule. So much drooling. I really enjoyed my time on the Fox 40, and while it's expensive, I think it's hard to beat.

More info on the 2021 Fox 40

Timmigrant
Tim Coleman

Age - 37

Height - 183 cm / 6'

Weight - 86 kg / 190 lbs

Ape Index - 1.055 / +10 cm

Inseam - 81 cm / 32"

Race Enduro and Downhill

Bar Width - 800 mm

Preferred Reach - 500 - 520 cm (but this is stack and head angle dependent)

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Comments

cooperquinn
+2 Cr4w ollyh
Cooper Quinn  - Dec. 2, 2020, 11:23 p.m.

Yowza, I think Andrew has reviewed complete bikes that cost less!

Reply

grimwood
+1 ollyh
grimwood  - Dec. 3, 2020, 6:59 a.m.

Hi Tim, I’m sure this was a fun product to review! You also reviewed the Boxxer a while back. How would you compare the 2? Differences in small bump or mid stroke? Any noticeable difference in stiffness?

Reply

Timmigrant
+1 ollyh
Tim Coleman  - Dec. 3, 2020, 11:33 p.m.

From the top they're both fantastic forks, and I'm not just saying that. Both the 40 and the Boxxer are excellent. I would not be upset to ride / race on either. But if I were to pick one, it'd be the 40. The 40 is a bit more precise, I like the chassis stiffness, and the GRIP2 damper allows me to run the fork more supportive, but without it ever feeling harsh. I also like the air bleeders on the 40, and the integrated mud guard is excellent.

Reply

dave_f
+2 Deniz Merdano ollyh
dave_f  - Dec. 3, 2020, 7:50 a.m.

It's interesting that the Enduro forks being run with similar head angles (Fox 38) are offered with 37/44 and 44/51 offsets, but the downhill forks are 48 and 52. Why do Enduro bikes need more trail than downhill bikes?

Reply

denomerdano
+4 Nouseforaname Mammal AJ Barlas Chad K ollyh Ceecee
Deniz Merdano  - Dec. 3, 2020, 8:15 a.m.

Enduro bikes are ridden at much slower speeds and often uphill.

64⁰ bike would have a floppy steering with longer offset. The reduced offset mitigates that greatly.

Reply

AJ_Barlas
0 Deniz Merdano Ceecee
AJ Barlas  - Dec. 3, 2020, 3:06 p.m.

Words from mouth, taken. :D

Reply

D_C_
0
DMVancouver  - Dec. 4, 2020, 7:41 a.m.

From my experience, running a short offset fork requires a head angle about 1 degree slacker than with long offset to not feel like the front-centre is too short. We were all fine with 65 degree head angles on enduro bikes until the short offset fork thing happened.

How come DH bikes haven’t gone short offset with even slacker head angles?

Reply

dave_f
0
dave_f  - Dec. 4, 2020, 11:05 p.m.

Thanks for the reply, maybe it has to do with the difference in speeds and use. Looking for the formula for flop, I find flop=trail*sin(ha)*cos(ha) where ha is head angle. So the forks with short offset (the Enduro bikes) should have "floppier" steering if the head angle is the same.

Reply

Ceecee
0
Ceecee  - Dec. 5, 2020, 7:18 a.m.

Flop is proportional to trail, according to this article:

https://www.adventurecycling.org/default/assets/resources/20140601_MechanicalAdvantageTrail_Heine.pdf

Bikes that will be turned at low speed need more 'power steering.'

Hopefully the terms in the article jibe with your math.

Reply

Ceecee
+2 DMVancouver ollyh
Ceecee  - Dec. 4, 2020, 10:42 a.m.

Because they have less travel, steeper HTAs--barely--and weighting front wheel is more of an issue for non-downhill gradients. Steeper STAs which favor pedaling mean longer reaches in order to conserve 'effective' toptube lengths. But longer reaches favor shorter stems, and shorter stems introduce weighting difficulties. It's weird that the steering and pedaling departments are virtually independent, yet have to be considered simultaneously due to their complex connective tissue.

Boxxer appears to have offset options if you'd like to increase trail on your DH or dual crown enduro unit.

Reply

colemaneddie
0
colemaneddie  - Dec. 3, 2020, 3:46 p.m.

Crazy question for you. Many are saying that the Zeb and 38 are basically as stiff and planted as a Boxxer or a 40. Do you think that argument holds up?

Reply

Timmigrant
+2 Jakub Gábriš ollyh
Tim Coleman  - Dec. 3, 2020, 11:20 p.m.

As the old car guys would say, there is no replacement for displacement. Single crown forks have come a long way, and we all rip on the Zeb and 38. But the current downhill forks are a significant step up in stiffness and precision.

Reply

JVP
0
JVP  - Dec. 4, 2020, 9:08 a.m.

And CSU durability.

Reply

Timmigrant
+1 ollyh
Tim Coleman  - Dec. 4, 2020, 12:52 p.m.

And that too! I don't find the Zeb and 38 near as stiff and planted as a Boxxer or a 40. I mean the 38 and the Zeb are excellent, but I'd still far rather a downhill fork on a downhill bike.

Reply

Angu58
+1 Tim Coleman
Angu58  - Dec. 5, 2020, 6:24 p.m.

Cool review, with some pretty good photos of the bike.

I saw you testing this in august, while you were in the lift line. bike looked great in person.

Reply

Timmigrant
0
Tim Coleman  - Dec. 8, 2020, 10:09 a.m.

Thanks for the kind words! The Sender with that fork on it is just gorgeous isn't it. Full review of the Sender should be coming out in the next couple weeks.

Reply

leon-forfar
+2 Tim Coleman ollyh
leon-forfar  - Dec. 7, 2020, 8:40 a.m.

Nice write up! Interesting about the harshness out the box. A buddy of mine and myself are both running the new 40, and found it incredibly hard to equalize the air chambers out the box. He took his apart and found a huge amount of grease in the air side, and it was clogging up the transfer ports. Mine was literally locked out once I had it up to pressure. Trying to get it to equalize was VERY annoying during the set up phase Once the correct amount of grease was in there, it made the fork A LOT smoother and it equalized no problem. If you didn't take yours apart, that may explain some of the harshness. I personally found the 2021 40 to be a "perfection" of the 2020 Grip 2. While I didn't add any additional volume tokens (I know, I should have, but I was lazy) in the 2020 fork, I found it too not have enough support, but it offered amazing traction and comfort. This new version has all that suppleness, but with the right support without having to go crazy with the tokens. It just seems to react EXACTLY how I imagine it to in every scenario. One big thing to note about the 27.5 version (which I have) is that the stock flat upper crown it comes with does not fit a good number of size medium and up bikes. I'm on a large 27.5 V10 7, which has a head tube length of 115mm (plus the external cup) and the 40 would not fit. The lower crown would bottom on my fender, while the stanchions BARELY made it into the top crown. I had to get Fox to send me a drop crown, and now it is on no problem:) A friend of mine had the same experience on her Commencal Furious which has a 125mm head tube.

Reply

Timmigrant
+1 ollyh
Tim Coleman  - Dec. 8, 2020, 10:17 a.m.

Great comment. Thanks for the kind words. Whenever adding pressure to a fork, especially after adding tokens I always equalize the fork / shock at increments as the pressure goes up. It took longer to equalize the air chambers than some other forks now that you mention it, but I didn't think much of it at the time. The fork felt buttery smooth to me in the parking lot, but the it was just a bit harsher than I remember the 2020 40 being. I don't know if it was temperature, break in, or me finding the right settings, but after a few rides it felt amazing.

As for the tall head tube, that's really interesting. I actually had the opposite problem. I was happy with the bar height on the Sender with the Boxxer installed. When I installed the 40 at the same bar height the top caps hit the handle bar. So I had to either add spacers under the upper crown, or extend the fork. I chose to do a bit of both. The headtube length on the size Large Sender CFR test bike is 110 mm, with a 20 mm spacer.

Reply

leon-forfar
+1 Tim Coleman
leon-forfar  - Dec. 9, 2020, 10:12 a.m.

Yeah, typically I cycle the fork every 30ish PSI to equalize it (mines at 101PSi), but it just wouldn't equalize at all. I ended having to equalize it every 5-10 psi would allow me to equalize. The 29er 40 comes with the drop crown stock, which definitely allows for some spacer adjustments up front. Just strange that the 27.5 comes with a flat crown. Once the drop crown was on, it was no issue and I had some wiggle room.

Reply

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