Inverted, Carbon Fiber XC ForkProprietary Hub -
The RS-1 name may be one that some riders recognize from many years ago, but the fork itself isn't like anything else currently on the market. Yes, there have been plenty of upside down forks over the years, and even a few single crown versions, but none have benefited from the all-encompassing approach to fork design that RockShox has put towards the RS-1. This includes not only the lightweight, one-piece carbon fiber upper legs and steerer tube assembly that only recently became possible to manufacture, but also the proprietary Predictive Steering design that includes the fork's dropouts, the clever hub, and how the two mate together to add rigidity to the fork. All of that doesn't come without a hefty price tag, though: the $1,865 USD RS-1 has been designed with cross-country racing and trail riding in mind, and can be run in 80, 100, or 120mm travel settings depending on how you're looking to use RockShox's new 1,666 gram fork.
RockShox RS-1 Details
• Purpose: cross-country / trail
• Chassis: inverted, one-piece carbon upper, 32mm stanchions
• Steerer: tapered carbon
• Spring: Solo Air w/ Bottomless Tokens
• Travel: 80 / 100 / 120mm
• Damper: Accelerator cartridge
• Lockout: XLoc hydraulic remote
• External adjustments: low-speed rebound, spring pressure
• Offset options: 46 / 51mm
• Wheel options: 29” only, with proprietary hub
• Axle: Predictive Steering w/ 15mm Maxle Ultimate
• Weight: 1,666 grams
• Predictive Steering hub MSRP: $238 USD
• MSRP: $1,865 USD
The stout looking carbon upper structure of the RS-1 certainly adds rigidity to the package, but RockShox says that the real key to them being able to manufacture an inverted, single crown fork with adequate torsional stiffness is its Predictive Steering design. That name refers to the fork's larger than usual closed dropouts and the Torque Tube hub that houses a pair of massive sealed bearings. There's one bearing on each side, with them sitting on a 27mm diameter axle that spans the hub, and a 15mm Maxle Ultimate runs through the center of all of this to compress the left and right dropouts together onto the matching hub-ends that fit into the dropouts. The fork and the $238 USD hub must be used in unison for the fork to function - there is no subbing in a different hub - which ties RS-1 owners to the SRAM and DT Swiss branded hubs, as the company has no plans to license the design out to anyone else. Damper Tech -
RockShox has long used different variations of their Motion Control cartridge in their SID cross-country forks, but with the advent of the Charger damper that's employed in the Pike and BoXXer forks, it's clear that they are taking a different approach to damper design. This change consists of going from the emulsion dampers (a design where the damper oil is free to mix with air in the system
) to a closed design that utilizes a compensator to, you guessed it, compensate for the volume displacement of the damper shaft entering the cartridge under compression. This layout means that there is essentially no air inside of the damper, and also back-pressure from the compensator, thereby greatly limiting the chance of the oil foaming and the fork acting unpredictably. That's all well and good, but due to weight concerns with the RS-1, RockShox decided to go a different route than to drop in their much lauded Charger damper.
Enter the Accelerator damper cartridge. Rather than an extruded bladder that expands under compression as used in the Pike, RockShox has gone with a more conventional spring-backed internal floating piston, otherwise known as an IFP. As the fork compresses and the Accelerator's damper rod goes into the cartridge, the IFP and the spring behind it are compressed and the added displacement is possible - without it, there would need to be air in the system, and the fork wouldn't compress at all if the cartridge was simply full of oil and had no compensator. After that, as the fork extends, the spring behind the IFP provides back pressure to keep the oil from foaming. It's not a new theory by any stretch of the imagination - it's essentially what's inside of a shock's piggyback, but with a spring rather than air pressure - but it is very effective. RockShox's dual-stage DIG valve has been employed to keep the fork up in its travel under braking, and they've also put in their two-stage Rapid Recovery valve system. Rapid Recovery is a high-speed rebound circuit that returns the wheel quickly after full impact events, while managing slower shaft speeds and mid-travel events with more damping control.
There are fewer external damper adjustments to be found on the RS-1 than with most of the competition: it sports a single knob at the bottom of the left leg to adjust rebound speed, and a handlebar mounted XLoc remote that can be used to firm up the fork on the fly. This likely won't make much difference to a cross-country racer who's going to want their fork to be either pretty stiff or really, really stiff, but trail riders who are used to twiddling dials on every other ride might find more spare time on their hands than they're used to.Inverted Air Spring -
It was pretty much a given that RockShox was going to use an air spring inside of the RS-1, but it's worth pointing out that the fork's Solo Air spring has, just like the fork's chassis, been turned upside down so that the Schrader air valve sits at the bottom of the leg. This was done for simplicity's sake, as it made a lot more sense to do that than to engineer a more complicated solution to keep the air cartridge sitting right side up. It still uses a self-balancing negative air chamber and, just like with the Pike and BoXXer, progression through the later stages of the fork's stroke can be tuned by adding or subtracting RockShox's threaded Bottomless Tokens.
I mounted the 100mm travel RS-1 to the front of my Rocky Mountain Element in early June, just in time for me to put some serious miles on it before heading off to the BC Bike Race, an event that served up more than 30,000 feet of descending on some relatively rowdy trails. The bike has also spent a considerable amount of time pointed down all sorts of singletrack on not just my home mountains, but also Whistler's infamous terrain, including an ill-advised trip down the notorious Gargamel trail. This often led to it probably seeing more than RockShox ever intended it to in regards to abuse levelled out, but there's certainly nothing wrong with that, is there? Nah. Sensitivity -
The spring rate that you settle on will obviously depend on where and how you ride, as well as how much you weigh, but the cross-country riding in my neck of the woods tends to be on the aggressive end of the scale in regards to what you should (or maybe shouldn't
) be doing on a short-travel bike, which often has me leaning towards a stiffer setup than what I would roll with elsewhere. Most short-travel forks suffer in regards to small bump compliance when under me simply due to the relatively stiff setup that doesn't allow for much in the way of suppleness, but the RS-1 is different. Very different. As far as short-travel cross-country forks go, it takes suppleness to unheard of levels, with a sensitive early stroke feel that is more akin to a fork with another inch or two of travel. This was so pronounced that the fork almost felt a touch under-sprung at first, even with the stiff setup. This is likely down to two reasons: a) the inverted design means that the fork's seals and bushings are more likely to be coated with lubrication oil. And b) the inverted design also means that near perfect alignment of the stanchions and upper assembly can be achieved, thereby ensuring that the fork is never fighting itself when being compressed.
When you're working with less, you really have to know how to use it, right? The RS-1 is the most sensitive and active cross-country fork on the market, of that I'm positive, which, in theory, should lead better ground tracking by the front tire and more traction. I'm not going to tell you that I took note of said increased traction, but I will say that anyone who rides the RS-1 will note how active and forgiving it is, even when run quite stiff. Air Spring -
The RS-1's Solo Air spring is very much geared more towards cross-country riding than any sort of hard charging trail bike shenanigans, and taking the latter approach quickly shows that its spring curve doesn't ramp-up fast enough or hard enough to keep the fork from gobbling up its travel faster than me eating a mid-ride Pop-Tart. That said, this is not an all-mountain fork, is it? No, it is a cross-country weapon whose air spring isn't designed for you to be chucking yourself off of anything that might require knee pads, and its stroke is meant to be more forgiving for its intentions than having it ramp up hard enough so as to keep flyweight racer boys from ever reaching bottom. I, on the other hand, could touch bottom pretty easily when I removed the two Bottomless Tokens that came installed inside the fork from RockShox, even when running on the extreme end of the recommended pressure range. With that in mind I'd tell that anyone who seeks out a spot of rowdiness on their cross-country bike to leave a few of those volume spacers inside of the RS-1.
The RS-1's air spring is too linear for my liking but, truth be told, I'm also probably riding it in places that are a bit above what RockShox really intends it for. The Solo Air spring does feel more appropriate on tamer terrain, though, and the option to easily add the Bottomless Tokens goes a long way to having it ramp up enough to keep nearly every rider happy. Fork Rigidity -
Just how stiff is the RS-1, both torsionally and front to back? First, a primer: inverted forks, and especially single crown inverted forks, have always been more akin to over-cooked noodles than pillars of accuracy, and trying to have them be as rigid as a traditional right side up fork usually results in them not only failing at that task, but also upping the fork's weight to a point where you just have to ask why bother. That said, out and out rigidity isn't the be all and end all decider of a fork's worth, is it? I've been on downhill forks that I've thought were too torsionally rigid, and I can say the same thing about some cross-country and downhill frames - some of my favourite bikes have been as flexy as a nubile yoga instructor. There's a point where a certain amount of flex is too much, but that point is further along than most riders think it is, at least in my mind.
Anyways, back to the RS-1... It is staggeringly flex-free front to back, enough so that I'd say it feels to be approaching what a downhill fork offers in that regard - there is simply none of the tucking feeling that can occur when the wheel is forced back under you during heavy front braking. This was pretty clear right off the bat, but I didn't fully understand how much so until I got off of my Rocky Mountain Element test platform that the RS-1 is bolted to and onto a 160mm travel bike with what should be a much stouter fork - yes, I know it's longer and has more travel, but it should also be stiff all around - and came away surprised at the difference, especially when I jumped back on the Rocky. Advantage RS-1, at least when talking about fore-aft rigidity.
It's not quite so cut and dry when talking about torsional rigidity, a much more obvious performance characteristic to most riders. Yes, the RS-1 feels as flex-free as it needs to be, and it certainly has a leg up on other pure cross-country forks on the market, but it might not be so much that one will have their minds blown by its torsional stiffness. It is more rigid than other short-travel forks, but I've honestly never felt that a RockShox SID or Fox 32 were so flexy as to be holding me back when I'm riding a 100mm travel cross-country bike in the manner it's meant to be ridden. On the other hand, it's all about incremental improvements these days, and the RS-1 is definitely more flex-free all around than the other 100 or 120mm travel contenders out there. The question is, does having to run the proprietary Predictive Steering hub make that gain worthwhile, and I guess the answer will come down to whether you mind being locked into that hub / front wheel or not. The Predictive Steering design is the biggest single factor in the fork's performance, after all, and the RS-1 likely wouldn't have come to fruition without it. Damping -
How much performance should one expect from a 100mm travel fork? Well, if it costs as much as the RS-1, I think we should all expect a lot of it. The fork's sealed Accelerator damper comes through on that front, giving the RS-1 great control on rough ground. It's still a 100mm travel fork, so don't go expecting the roots and rocks to part so you can ''Sam Hill'' your cross-country bike, but there's a noticeable step up in composure compared to the SID's Motion Control DNA damper. I say this after having spent multiple seasons on a SID, and at the time never feeling like it left me wanting for more relative to its intentions. However, it's clear that there's a gap in damping between the two forks when pushing hard.
I'd describe it as just simply having more control in a lot of situations, especially repeat impacts that put the fork deeper into its travel, and that translates to you feeling like you have just a bit more in hand if you need it. Combine that performance with the stiff fork chassis and the RS-1 as a whole feels like much more fork than you might expect given its travel and weight figures. I did still find myself wishing for a separate, crown mounted low-speed compression knob as is available with the Motion Control damper, mostly so I could dial-in some added low-speed control over what the stock cartridge supplies. I didn't find that the fork dived too excessively, actually, but it was so supple that I sometimes found it a bit too active. I guess that's what the XLoc remote on my handlebar is for, though. On the other hand, I don't see a lot of high-performance trail riders being willing to swap out low-speed compression adjustment for a handlebar mounted remote. Other Details -
With moulded-in guides that use snap-in plastic housing retainers, the fork's front brake routing is more dialled than we've ever seen from the competition, but at the same time it's a given that you don't want said housing to be rubbing on the carbon uppers for months and months on end. There looks to be a rather thick application of clear coat applied to the carbon that would likely require you to be a real dumbass about it in order to cause any real damage over the long haul, but you'll still want to make sure that your front brake line is just the right length, and that you've applied the included protective stick-on decals in any areas where it might make excessive contact.
I don't like remotes. Not one bit. Which is why I'm bummed to see that the RS-1 only comes with RockShox's hydraulic XLoc remote system - there is no crown-mounted compression option. I know it's a cross-country fork and that those Lycra weasels lock out their suspension even when just talking about a climb, but the SID is made with the same intentions in mind and it has a crown mounted low-speed compression dial and lock out option should one choose to go that route. XLoc works quite well, there's no doubting that, but I'd rather not have it as I don't often firm up my fork. Racing cross-country? You might think differently, then.
With no guards to protect the lower legs, my RS-1 test fork must have some banged up stanchions after the months and months of riding I've put it through, right? Wrong. There isn't a single scratch, ding, or any mark whatsoever on them, and that's even after the bike spent a full week being transported
inside of a semi-trailer with a few hundred other machines during the BC Bike Race. I've ridden and crashed horribly on rocky, pointy terrain; I've lent the bike out for others to abuse like it was their own; I've had it in the back of pick-up trucks on rowdy 4x4 access roads. I stopped worrying about marring the stanchions long ago, and now treat it as any other fork. I know many out there will be assuming that its lower tubes won't last more than a few weeks under them, but I'm personally more concerned about an oncoming alien invasion than scratching up the RS-1. You fret about the fork's stanchions while I wear my tinfoil hat, okay? Pinkbike's take:
|The RS-1 is expensive, requires a proprietary hub, and obviously has a pretty small target audience. Those facts alone will make it more of a ''pig in the window'' for RockShox than a fork most would consider purchasing. However, if you put those points to the side and only look at the RS-1's performance, you'll find that it's stiffer and offers a better (but less adjustable) damper than its predecessor, the SID. It's a safe bet that the proprietary hub is going to put off some potential buyers, although racers will often look past such things for even the smallest of gains in performance, and that's the exact group of riders who I see not minding the whole "no hub, no RS-1" thing. As for the more casual riders, the ones who might not plan on regularly toeing the starting line but still like to have the latest gear, taking the same approach will put them aboard the best cross-country fork on the market, as long as they can afford the eye-watering cost of entry.- Mike Levy|