Check out Rotorburn member Zaf's in depth review of the SR Suntour Durolux R2C2 fork.
Item: SR Suntour Durolux R2C2
Cost: $650AUD (includes postage)
Purchased from: Bike Components (Germany) & SR Suntour North America
Usage: I have run two separate version of this fork, a 650b on my Yeti SB5 and the 29er on my Trek Slash 9.9; cumulatively dropped about 2000km onto them.
- Sturdy construction and feelCons:
- Performance tuning wet dream
- Easily user serviceable
- Completely user serviceable with good documentation
- Heavier than competitors
- Noisy during operation
- Complicated setup
- Name already taken by a weatherproof paint in Aus
- Brand commonly associated with lower quality OEM products on entry level bikes
Fork Internals and Design
The heart of the Durolux is the R2C2 damper; and as the name implies, it has two (High and Low speed) controls for both the Rebound and Compression circuits on the fork. Without any surprise break from he norm, the rebound controls are found at bottom of the right fork leg, and the compression knobs at the top. The dials on all but the high speed compression knob have very distinct detents that are very easy to adjust; the high speed compression doesn't "click in" in the same manner as the others, but is very clearly labeled on the pointer dial where it is in it's 130° of adjustment.
Both high speed controls have five steps in total, with each step making a significant jump in the damping property of the fork. The low speed controls have 20 clicks of adjustment and although there is an appreciable difference between the two extremes of the controls, I found I had to turn about 3-4 clicks stages to notice a difference in the damping characteristics whilst on the bike.
The Damper itself uses a spring loaded Infinite Floating Piston (IFP) to manage changing oil volumes within the compression/rebound cycle of the fork. This cartridge can be bled without even removing the damper from the fork, via a very intuitive process of removing the top cap and the small 10Nm spring on the IFP, adding oil and cycling the damper until any bubbles have cleared. I have never had to actually employ this cycle from loss in damping quality however, in each case the damper has proved amazingly reliable. I say it because this can be done at home with a screwdriver, a wrench and some correct weight oil, and doesn't require $300 of pressurised syringes, and a full fork breakdown like anything with a bladder system.
Worth noting for those who want a quiet ride, this is not a silent damper, and if you find yourself running more compression and rebound damping on your circuits, it does get noisier past that. I personally don't mind the noise, it's a confident squirt of oil running through circuits, but it is noticeable, and if you're someone who doesn't appreciate that kind of noise during operation, you're not going to get along with this at all.
The left leg houses the air spring for the fork. At the top of the fork you'll find the solo air valve to set your sag pressure against. This assembly can be unscrewed to reveal a piston that sits into the air chamber; placing up to three clipped spacers behind this piston is how the fork adjusts it's air volume for bottom out (these same clips are used on the shaft to reduce the travel).
A coil negative spring is in place of an air equalizing port within the shaft. There are several different spring pressures available from SR Suntour for if you're a heavier or lighter rider. If you order the fork through the North American site and the WERX program, it will come pre-fitted with the ideal spring for your weight range. As always with this fork it is extremely easy to work on and removing the lowers, spring assembly and then switching out the negative spring is a 15min job requiring a shifter, and a 10mm and 12mm socket (the lowers don't even require drifting out with a mallet).
The forks come without any oil in the lowers from factory, only a light slathering of suspension grease on the seals and within the air shaft, and they run and operate smoothly and efficiently with this. If you would like to, 10cc's of suspension fluid is commonly run in the lowers by those with the fork to get the extra bit of performance. The fork also has service ports for the addition of this fluid right behind the foam rings and halfway down the lowers, so it's not even required to drop the lowers in order add this into the fork. If you do this, Suntour's only recommendation is to be more diligent with your service intervals, as the fluid is more prone to attracting grime into the fork than the grease alone.
In both cases during my testing, I was running 10cc of Fox Gold w30 in the lowers of each fork leg.
There is a well designed integrated fender that bolts directly into the bridge and the upper tubes of the lowers. I was running 2.5 Maxxis Minion DHF or 2.4 WTB Convicts with plenty of space to spare. It is worth noting that although it's a harder plastic than the icecream bucket/ziptie deals usually put into forks, it is a little more brittle. Living in Alice Springs, my fenders are more to keep flicking rocks and dust off my sliding surfaces; with the large tread tyres that can pick up rocks for a few rotations, you can hear these whipping past the plastic when they carry through. On the Yeti this caused a crack in the fender on the right side between the two bolt points.
That being said, replacements cost about $30 and I've only had the single fender fail in this manner. In the few wet rides I've gotten out on the fork (do excuse that they're pretty rare up here), it does perfect work at reducing sand, water and mud being flicked up into your face.
SR Suntour's air pressure charts are a bit off, and admittedly I trusted them for a few rides too many to begin with on the Yeti trying to get the fork dialed, something hard to spot as the different spring pressures were achieving same sag results. In any case, I usually aim for about 20% on my forks, liking a stiffer spring pressure up front, but settled for a little softer (22-23%) in this case.
The bottom out tokens make a significant difference to the fork ramp behaviour, and unlike the Fox and Rockshox options I've used in the past where the ramp comes in the last quarter of the stroke, the Suntour begins to ramp from about the halfway up the shaft. A single token with my spring pressures was more than adequate to never have me slam the bottom out bumper.
I also used the medium negative coil spring in both forks. It's worth getting the right spring for your weight in this case, you'll notice as you remove air from the positive chamber the fork will pull down into it's travel as the coil negative will apply a constant pressure to the shaft. If you have too soft a negative spring for your weight range, you're going to get a much harsher ride, and too stiff a negative spring will cause the fork to remain lower in it's travel as the positive pressure won't be adequate to overcome it.
Low Speed compression and rebound settings were kept around about the middle third of their range, with a single click of High Speed Rebound being used and 2-3 clicks of High Speed compression.
The fork is the stiffest chassis I have ridden to date. Large 36mm stanchions are matched to an overbuilt crown and a huge, wide bridge on the lowers, all cinched up with a brilliantly designed expanding axle. It comes a slight weight hit, out of the box (no star nut or cutting of steerer tube or addition of lowers oil or fender) the fork hit the scales at 2250g in the 29er form. I never noticed the weight on the bike, it's something you can feel if you're holding it in opposite hands to a Fox 36, but otherwise just a number on the page.
Ride quality was a mixed affair when I first started out, as I mentioned previously, the Yeti had a bit of an adjustment period in which I was running far too stiff spring pressure which was causing a lot of hand fatigue and feedback. Once this was lowered to correct pressures things fell into place very quickly, although the large range of adjustment did require a lot of changes and testing to settle onto the desired settings. It's a double edged sword this one, if you spend the time with it and experiment a little, you'll find you can get some really special things out of this fork, but the big range in settings and difference in them means that it's not a simple setup and the fork doesn't feel that great if it's maladjusted.
The Durolux has no equal to how high it rides in its travel. This is not a fork that ever seems to dive in on itself or give up travel unnecessarily. It's low speed compression has a far more tangible effect on brake dive than its competitors as well as no notable flex during hard braking. Steering quality follows this trend, with a stoutness and confidence in throwing it into a line and having it hold the pointed line, if it deflects, it has everything to do with the rider's upper body strength and not the fork.
As noted earlier, the R2C2 damper makes an audible oil squirting noise throughout operation. It's also worth noting that on medium continuous impacts (bombing down steps being a notable example), you can also hear the coil of the negative spring rattle a little. This is not a common noise, and could potentially be solved with some electrical heat shrink sheathing, but it's not the nicest noise when it does happen.
I have been so impressed with Durolux's performance on the Yeti that I found myself switching out my Factory Fox 36 RC2 on the Trek for one and have not looked back. Out of the box, it does have a complicated setup, but once tuned will outperform any of the top forks on the market in everything except weight, and it will do that for half the price.
Without a doubt, this is the more user friendly fork currently on the market. Not only is the strip down process extremely simple and intuitive, it requires few tools (none of which are proprietary) and is well documented by the company. There are also convenient ports that can refresh the fork between larger servicing intervals.
If you want silent operation and count grams, save your pennies for one of the offerings from Fox and Rockshox, otherwise you'd be well served throwing this on the front of your bike and charging headlong into whatever you chunk you can with confidence.
Note: I have recently installed a CRConception Damper and Coil conversion kit into the 29er Durolux and will be reporting back on the changes this makes to the fork.
@hifiandmtb that should cover it.