In 2008, Gee Atherton took out the senior men’s Downhill World Championships in Val di Sole – the first ever senior men’s DH world champs win on a fully Fox-equipped bike, only a few years after Fabien Barel snared the first ever world champs victory on a Fox rear shock. For 2009, 200 replicas of Atherton’s fork and shock were made available to the public. Thanks to Netti Atom and Ken @ TeKin Suspension, we’ve been able to test these for the past few weeks.

  

 

The fork, sold as the 40WC, is not dramatically different to a stock 40RC2. It still features the same chassis, the same external adjustments (rebound, high and low speed compression, and preload), and the same damper construction as the stock 40RC2. It does have a couple of changes though, in order to bring it up to Atherton spec:

 

Essentially what this means is that the fork is set up with a stiffer spring rate and with more compression damping out of the box, than the stock 40RC2. This is intended to allow for more aggressive riding than the standard RC2 provides for, by preventing the fork blowing through its travel. The only part of Gee’s fork you don’t get is the silver stanchions, which wear out too fast to become production items apparently.

 

The DHX RC4 will be available in 2010 as a successor/uprgrade from the current DHX. Unlike the 40WC however, the DHX RC4 is a significantly different beast to ye olde DHX5.0, having a bigger damper shaft (5/8” instead of ½”) as well as the following external damping adjustments:

 

  

After bolting the fully sick shockies to a Banshee Legend, Ken from TeKin spent a couple of days helping with the setup, which let us try tuning methods that just aren’t available if you’re doing it all on your own. The way we approached the setup was to establish a rough baseline setup as quickly as possible from direct rider choice, then to essentially make “blind” adjustments based on rider feedback after each run. This meant that I would do a run, tell Ken what I thought could be better and what worked well, and he would make adjustments to the suspension without telling me what he was doing. After the next run, I would tell him what changes I felt, and whether it was better or worse, and he would make adjustments accordingly – or sometimes make no adjustment at all, just to see what the placebo effect could do. This eliminated the possibility of rider preconception affecting what was found to be the best setup, or providing dishonest/biased feedback. In short, it stopped my gigantic ego getting in the way of genuine improvements, which of course us armchair experts find very humbling and hard to admit to outside Wankers Anonymous meetings. Ken’s test/setup notes can be found in the following links for those who are interested: 

 

 

 

Having ridden a few 40s before, I had some idea of what to expect. The stock 40RC2s have virtually zero stiction, and an action that's as light and smooth as a well lubricated bodily orifice, and of course using the same chassis, the 40WC was no different. The 40RC2s have always been unfortunately lacking in compression damping, having a super light compression tune that meant that twiddling the adjusters seemed to make essentially bugger all difference to the feel of the fork – especially if you’re a 94kg heavyweight like myself, where you'd have sworn that the adjusters were actually purely cosmetic and not even connected to the damper. The firmer compression tune of the 40WC meant that the compression adjusters had a perceptible effect on the fork even just bouncing on the thing in the carpark, which was a clear improvement over the older 40RC2s.

 

There are a lot of little things I really liked about the Fox, that I think most of their competitors could stand to take note of. First of all is the axle: it doesn’t suck. There is no gimmicky crap, no way you can strip out the lowers, no plastic, no ridiculous attempts at “quick release”, no anything that I could see that could actually easily go wrong. There’s just a stepped axle (which allows for the varying tolerances between hub width spacing and the spacing of the lowers themselves without just bending the lowers in) and pinchbolts which thread into replaceable inserts. All the structural hardware uses a 5mm allen key, no silly little 3mm or 4mm heads, even in the crowns. It’s great to see a major manufacturer actually use some common sense with this sort of stuff – it’s not rocket surgery but it’s been gotten wrong more times than right. Even little details like the cover over the compression adjusters just show that some forethought really has been put into the design of the fork. The adjuster knobs have distinct clicks, and a light action that doesn’t just feel cheap and nasty like some.

 

On the trail, we first tested with a Blue (medium) spring, but found that even with both compression adjusters wound fully in, the fork blew through its travel too much on bigger hits and steeper/faster sections of track, meaning that I had to ride further over the back than I would have liked, and giving a sensation of being a bit too likely to go over the bars. Unsurprisingly, the small bump absorption was great with this setup, and the fork felt very smooth, with sharp hits to the wheel becoming very muted bumps through the handlebars, though this lack of harshness wasn’t really as much a priority as stabilising the bike. We swapped out the spring to a Green (firm) spring, which helped but still didn’t give quite the feel I was looking for. Interestingly, after the first day of testing, I found the fork rebound set a bit slower than I would typically set it – testament to the value of blind adjustments in removing rider preconceptions from setup, as well as the ability of Fox’s rebound damping to keep the front wheel on the ground even when set relatively slow.

 

After the first day of testing, Ken rebuilt the damper with an additional shim in the stack, which made a significant difference and finally gave the fork the heavier compression damping I was looking for. It has to be mentioned that even for someone with Ken’s expertise and all the right tooling, servicing the fork from beginning to end can take 2-3 hours if the sealed FIT damper needs to be rebuilt and bled.  This is an unfortunate detraction from the appeal of the fork in my eyes, given how easy it is to service some of the competitors’ forks. In fairness however, changing the lubricant/semi-bath oil in the lowers is as easy as on any other fork, and the damper shouldn’t need servicing anywhere near as regularly due to being sealed and separate from any contaminants in the lowers.

 

Once we got stuck into the second day of testing/setup, the more heavily damped fork showed a lot of promise, riding higher in its travel, giving something firmer to push on in the corners and g-outs, and greatly reducing the feeling that if I hit stuff too hard, that the front of the bike would just give way and send me OTB. This began to really feel like I’d hoped it might, with the firmer compression basically meaning that the bike wasn’t blowing through travel unnecessarily, yet still avoiding harshness or kicking on the particularly sharp hits, like big rocks in rock gardens. I still ended up running the fork at very close to maximum compression damping, with medium-speed rebound, and I found that I could actually get away with the lighter spring, although for the most part I still preferred to use the stiffer one. However, running that much compression damping, the fork began to lose its super free-moving action, which meant that on high speed fire roads where all the bumps might only be an inch or two high, a fair bit more vibration was getting through to my hands. As a result, while racing at Big Hill, I ended up backing both the low and high speed compression off a little more in order to free up the suspension a bit for the really small chatter bumps. The compromise was that, despite Fox’s hydraulic bottom-out resistance circuit, the fork did tend to blow through its travel a little more. In this case I believe more high speed and less low speed damping may have been beneficial, but it was impossible to achieve greater high-speed damping without revalving the damper again, so a compromise was (as always) struck. 

 

Disclaimer: this paragraph and the next are for tech nerds only. 

One issue with the compression circuit is that the threshold between the high and low speed is at a relatively low level of force, which means that in order for the low speed adjuster to do anything much, the high speed adjuster had to be wound in a fair way – in my case, the usable range was within about 4 clicks of full-in. This does raise a question mark in my mind about the choice of springs for the high speed adjuster, which simply increases/decreases preload on a spring that holds the sealing shim to the compression piston. Even with the high speed adjuster wound all the way in, and the low speed adjuster all the way in (meaning the low speed circuit was completely closed off – no oil could get through, all oil had to go through the preloaded shim stack), the “blow-off” even just bouncing on the fork was fairly soft. This basically means that the high speed preload spring is quite soft, and as a result, the high speed compression damping is more dependent on the shim stack configuration than the setting of the high speed adjuster – even with the HSC adjuster all the way in, the fork wasn’t harsh or unable to use all of its travel, which meant that the available external adjustment range just didn’t allow for a particularly high degree of compression damping without revalving the damper. Again, revalving is entirely possible with this fork – but given how little damping there is when the adjusters are backed right out, I don’t really understand why Fox haven’t gone for an overall firmer setup (especially in the older model forks that only had a single shim), as riders looking for a light compression tune still wouldn’t have too many problems getting it with the adjusters backed out.

 

The guts of the FIT damper are very impressive, with lots of intricate precision-machined parts, truly separate compression and rebound damping circuits, a sealed and bled cartridge which ensures a consistent stroke with no aeration (foaming) of the oil, a positive-pressure damper layout that prevents the possibility of cavitation, an internally adjustable hydraulic bottom-out circuit which ramps up the compression damping in the last inch and a half or so of the stroke, and so forth. Everything inside the damper just gleams of quality – everything seems to be very well finished, the fit between parts is very snappy, and all the moving parts move smoothly and freely. The 40’s damper construction is distinctly nicer than any of its mainstream competitors that I’ve seen, and appears to be a great platform from which to work.

 

The Fox FIT damper is entirely capable of being revalved to pretty much anything you like – this is a big advantage of the Fox damper over Marzocchi’s non-user-serviceable cartridges and Rockshox’s Motion Control setup (which in fairness is about to be superseded by the shimmed Mission Control dampers). However, as mentioned before, bleeding the damper is a pain in the arse, and as a result is something that will put a lot of owners off fully servicing or revalving their own forks; however in terms of performance, there is nothing actually stopping you from revalving a stock 40RC2 to perform identically to this one, and this is a service Tekin are able to offer. Obviously reliability can’t be commented on without owning the forks long-term, but there doesn’t appear to be any reason why they’d differ from the existing 40RC2s, so find a mate who’s owned a 40 for a while and ask them how they fare in that regard.

 

Relatively minor gripes aside, after a few weeks riding it, I was pretty stoked on the 40WC. It did a good job of keeping the wheel on the ground, and in my personal opinion, the rebound damping in them is stellar and second to none – the usable range is quite large, and even when slowed down quite a bit, they don’t seem to suffer from packing up in fast chatter and braking bumps. With Tekin’s heavier compression tune, the compression adjusters actually made a noticeable difference and gave a good working range, letting me bash into rocks and mash the bike into corners and g-outs without the fork feeling like it was disappearing from under me, or feeling harsh through really rough stuff. As previously mentioned, I still think the tune we had could possibly be improved upon, in order to increase the very small bump absorption a bit without detracting from the fork’s ability to maintain a good ride height and keep the bike from pitching around too much, but that has to be kept in perspective – it’s already very good. 

 

 

 

 

The DHX RC4 is fairly close to “new from the ground up” from its predecessor, the DHX 5.0. The shock barrel on the RC4 is the same size as the DHX 5.0 (referred to from now on as just the “DHX”) and it uses the same springs, but where the old DHX had a “Propedal” adjuster that did pretty much the same thing as adjusting the air pressure (close enough that dyno testing couldn’t show any difference between adjusting Propedal and adjusting air pressure), the new RC4 has separate  high and low speed compression adjusters. These are, unlike the old Propedal adjustment, apparently completely separate from the position-sensitive Boost Valve, which still gives the RC4 adjustable bottom-out resistance in the same way as the old DHX. 

 

Due to the air pressure in the shock affecting the compression damping, there is in fact some significant overlap between the high/low speed compression adjusters and the air pressure adjustment – without dyno testing, it’s impossible to know exactly what the overlap is, but if it’s anything like the old DHX then increasing the air pressure would affect the entire range of compression damping. As a result, we decided it would be simplest to set an air pressure more or less arbitrarily, then use the LSC/HSC/bottom out adjusters separately to reduce the number of variables that would be affected by adjusting the air pressure directly. We set the air pressure to 150psi (the range specified by Fox is 125-200psi) then went about setting the shock up to my liking. 

 

 

I have typically run 350lbs/in springs in the past, on Cane Creek Double Barrel and BOS Stoy shocks, with good results – on the Cane Creek, I was running approximately 38% sag with this spring. However, when we mounted the 350lbs/in spring to the RC4, I was only getting 30% sag, and even dropping to a 300lbs/in spring only netted about 35% sag. This appears to be due to the huge shaft size on the RC4 – the 5/8” (15.875mm) diameter shaft has about 56% more surface area than a standard ½” (12.7mm) diameter shaft as found in an old DHX, Vivid or a BOS. The Cane Creek only runs on an 8mm diameter shaft, and is claimed to run very low reservoir pressures due to its design making it impossible for cavitation to occur. Basically, after a few quick calculations, we worked out that 150psi in the RC4 would equate to about 46lbs of preload (plus whatever the increase in force is from the decrease in chamber size as the shock compresses), which on its own would pretty much explain why the Cane Creek could run a 350lbs/in spring with more sag than the RC4 with a 300lbs/in spring – keeping in mind that the air chamber would also have a significant air spring effect within the shock, in addition to the coil spring. Of course, every shock has this to some degree, but it is only the RC4 where I’ve ever noticed it or found it so significant that I had to change the spring rate because of the air spring effect alone. The air effect also means that the shock doesn’t feel sensitive at all right at the top of the stroke when pushing by hand, it takes a bit of force to overcome that kind of air preload – not that this means a lot on the track.

 

 

The DHX RC4 has separate external LSC/HSC adjusters, as well as a reservoir roughly the diameter of your thigh. Check clearance before purchasing!
Photo: James Patterson 

 

Once the bike is actually into its stroke as per normal riding conditions though, the RC4 is very smooth. It doesn’t have quite the same holy-shit factor of the BOS Stoy, or to a slightly lesser extent the Cane Creek, in terms of how free-moving and frictionless it is, but it does seem to be improved over the old DHX, and it is also free of the hesitation/sticking feeling between the compression and rebound strokes that can be felt in older DHXs, or Vivids when the compression is turned up.

 

On the trail, the RC4 feels a bit more linear than the old DHX, mainly because it allows you to run a fair bit more low speed compression damping and use that to prevent the bike blowing through its travel, whereas by comparison the old DHX in stock guise didn’t really let you run much low speed compression damping before it just became harsh. The separate high/low adjusters are handy here, though like with the fork, to get any significant LSC out of the shock, the high speed adjuster needed to be wound in close to full. Technical explanations aside, basically the RC4 lets you run more compression damping in order to control the bike’s behaviour to suit your preferences, without becoming harsh like the old DHX was prone to doing. This means you can set the bike up to be more stable, more deadened, reduce kicking off lips, and so forth, than you could with the old DHX. 

 

Suspension good, cornering style bad!
Photo: Tony Pincan
 

However, again like the fork, the upper limit of the compression damping in LSC or HSC was not all that high at the 150psi chamber pressure – certainly nowhere near as heavily damped as a Cane Creek can be, nor quite reaching the levels of compression damping that the BOS Stoy can achieve, but still with a bigger compression range than a Vivid, and certainly a more useful range than a DHX5.0. In fairness, I didn’t actually “run out” of damping in the sense that I wanted/needed more, and being at the heavy end of the typical weight spectrum means that most riders should find the range very much usable – depending of course on the leverage ratio of the bike. Increasing air pressure to bump up the overall range of compression damping may have increased the amount of damping available, but due to the time limitations of the review, this option wasn’t fully explored. In any case, having that kind of overlap between compression adjusters means setup can be a bit complicated, but taking the simpler route as we did should net pretty well everyone a setup they’d like. Using the RC4 on particularly high-leverage bikes such as V10s may mean that they still feel quite lightly damped in compression, but this is speculation, and at any rate there is definitely more usable compression damping on tap than the stock DHX which many riders are happy with on such bikes anyway.

 

As usual with Fox stuff, the rebound damping is great, offering a wide range with usable increments between clicks of the adjuster, and again having to be run surprisingly slow before any packing up becomes specifically noticeable. I don’t believe there is any real reason to have quite as extreme a range as the RC4 has though – not that it really matters if you know how you want your rebound, but there isn’t much use for a rebound setting that literally shoots you out of the seat if you bounce on it, nor one where the shock’s rebound time would be measured on a calendar. Anyway this is just nitpicking, to be fair – the rebound damping is of Fox’s usual high standard, and provided it wasn't set up in a silly manner, the rear wheel typically stayed on the ground and behaved in a predictable manner.

 

Despite the added complexity with setup, I did like the adjustable bottom-out resistance on the RC4, which works in exactly the same manner as the old DHX. On the occasions where I did feel it bottoming out on heavy landings and the like, adding one turn of bottom-out resistance fixed the problem without doing anything undesirable like making the bike harsher elsewhere. As mentioned with the fork, I couldn’t comment on reliability without owning the shock for quite a while, but rear shock reliability is something Fox have usually had pretty dialled in the past, and I’d be surprised if this one bucked the trend – speculation though.

 

 

 

The fork and shock complement each other well – they both have a similar feel in both compression and rebound, they both feature similar adjustments (although the bottom out resistance in the fork has to be adjusted internally, and comes preset at maximum), and they generally work well to keep both ends of the bike working as they should in a balanced manner. At the end of the day though, with nitpicking aside, the 40WC improves on the already great 40RC2, and the RC4 is unquestionably better than Fox's previous benchmark shock in the DHX5.0. Both the fork and shock are extremely smooth, not prone to harshness, made to Fox's renowned tight tolerances, have usable, useful adjustments, and basically ride very well. The ride overall is quite lively, with the Fox suspension never really losing its “pop” when you want to jump it over stuff rather than just bashing through it, even with fairly heavy damping in both directions. This is great for those who love a lively, smooth ride (seems to be most people) but for people like myself who have a predisposition towards very heavy compression damping and the stability it brings, it would be nice to see the upper limits of the damping adjustments extended still further. 

 

 

This brings us to the next point – whilst various custom tuning options have always existed for most shocks, it is only recently that getting a shock custom valved has become popular in Australia. Ken @ Tekin Suspension has been doing this stuff for several years now, and specialises in Fox suspension in particular. Should you find that the external adjustments on your 40 or RC4 still don’t get you quite the feel you’re after, then Tekin have got you covered. The package available with the 40WC (which will soon be sold pretty much as-is for the next model year’s production version) and the DHX RC4 (which will also be available en masse) is great out of the box, and with the aftermarket tuning and support now available from Netti and Tekin, it’s hard to find any major criticisms or particular reasons why you shouldn’t go for such a setup. As usual Fox have provided a solid benchmark for the industry – not that their products are perfect, or even necessarily the best out there if ultra-high end boutique stuff is considered, but for the mass market they’ve got a very competitive package here. For those interested in purchasing a DHX RC4, please be aware that the reservoir is a bit bigger than the DHX5.0 - check clearance before handing over your money!

 

Rider Weight: 94kg

Test Bike: Banshee Legend Mk1

Suspension Average Leverage Ratio: 2.83:1

Suspension Rate: progressive to linear

Rear shock spring rate: 300lbs/in (350lbs/in also tested)

Fork spring: Green (Firm), Blue (Medium) also tested

Shock weight: 447g/0.99lbs (claimed), no spring, no hardware

Fork weight: 3.09kg/6.83lbs (claimed)

 

DHX RC4: $1099rrp with spring/hardware (projected for 2010, subject to confirmation)

40RC2 (functionally identical to 40WC reviewed): $2599rrp (projected for 2010, subject to confirmation)

Distributed in Australia by Netti Atom, http://www.netti.com.au

Servicing and setup advice provided by Tekin Suspension, http://www.tekinsuspension.com.au