You probably think of hubs or maybe rims when someone mentions the DT Swiss name, but the company also offers a lineup of ten forks under the OPM moniker that range from 100mm to 150mm of travel. It's the 120mm travel OPM O.D.L model that's reviewed here, a fork that DT Swiss says is, ''The choice of strong and aggressive riders.'' The $1,159 USD OPM employs DT Swiss' O.D.L damper that allows the rider to choose between Open, Drive, and Lock compression modes, either via a remote or by way of a crown-mounted lever, and the chassis features 32mm stanchion tubes and an interesting looking reverse arch design. What's Inside the OPM?O.D.L Damper:
The 29er OPM's 1,673 gram weight stacks up competitively against other 29er trail oriented forks, with Fox's 34 coming in at 1,805 grams and RockShox's Reba weighing 1,662 grams. The OPM's 32mm stanchions and lightweight chassis obviously help in this regard, and the fork better aligns with pure cross-country offerings from DT Swiss' competition. Regardless, the company says that the 120mm OPM slots into the trail / all-mountain spectrum on their performance chart.
OPM O.D.L Details
• Intended use: trail
• Travel: 120mmm
• Spring: air
• Damper adjustments: low-speed compression, three-position compression, rebound
• Low-speed compression tuneable in Open mode
• Remote or crown operated three-position compression
• Stanchions: 32mm
• Tapered steerer only
• 15mm DT Swiss RWS thru-axle
• Weight: 1,673 grams (w/ 16.5cm steerer, axle)
• MSRP: $1,159.00 USD
The fork's O.D.L damper is a closed unit, but DT Swiss have come up with a pretty clever way to incorporate a floating piston into the design that actually sits outside
the damper body. Nearly all rear shocks employ an air-backed floating piston, with its purpose being to compensate for fluid displacement - as the damper rod compresses into the shock, the spring-backed piston also compresses. This design allows the damper to be completely full of oil and have zero air in it, and it also provides important back-pressure to keep the oil from cavitating (foaming) when the shock is working hard. The same basic principles apply to the expanding rubber bladders that RockShox and Fox use within their forks, although the execution is different. DT Swiss, however, has chosen to use a spring-backed floating piston rather than a bladder.
The neat thing about the O.D.L damper is that the floating piston actually sits outside of the damper body, between it and the inner wall of the stanchion tube, and a number of small oil bleed holes that allow the oil to travel into and out of the cartridge as the fork compresses and rebounds. And, because the piston is sealed against the inside wall of the stanchion tube with a large O-ring, the cartridge is still a sealed unit without any air in it. Pretty clever.
When the fork is compressed, oil is forced up and through the compression assembly at the top of the cartridge, providing damping. The same oil is then forced out of the aforementioned bleed holes and into a small space between the cartridge and the stanchion tube, just under the fork's top cap. The spring-backed floating piston is compressed while providing counter pressure when the oil returns back through the bleed holes (both shown to the right).
This piston would usually be referred to as an IFP (internal floating piston), but it almost makes more sense to refer to it as an EFP (external floating piston) when it comes to the O.D.L damper.
NCS Air Spring:
When the fork is set to 'Open' mode, the oil flows through the low-speed compression channel where it's controlled by a tapered needle rod, the position of which is operated by the blue dial atop the fork leg. When the fork's 'Drive' mode is selected, all of the oil flow is directed to the high-speed compression circuit to provide a firmer feel, and when the 'Lock' mode is engaged, the oil bypasses both the low- and high-speed circuits for the blow-off channel.
Rebound damping is controlled at the opposite end of the cartridge, via the high-speed rebound piston and low-speed rebound orifice. When the floating piston pushes the oil back into the cartridge, it passes through the low-speed rebound channel at slow speeds, but higher shaft speeds force the oil to bypass to the high-speed, shim controlled path where it is better regulated.
The OPM employs a conventional air spring system that's adjusted by way of a Schrader valve at the top of the left fork leg. DT Swiss has gone with a negative coil spring (that's the NCS in the name) instead of a lighter weight air system that is self-adjusting, and while there is probably a slight weight penalty for this, anyone who's had their fork begin to suck down into its travel due to air moving from the positive to the negative chamber isn't going to mind.
There is currently no way to tinker with fork's air volume via volume spacers like you can with RockShox or Fox forks, but DT Swiss do say that they are working on an easily retrofittable design that will allow riders to dial in more or less progression through the stroke. The OPM's Chassis
The OPM's one-piece magnesium lowers feature a reverse arch that may remind some of us of a Manitou fork, and their reasoning is the same. The company says that the arch's position behind the fork makes for, ''more compact, stiffer construction than bridges that run in front of the stanchions,'' and a peek from behind reveals the lattice design that DT Swiss says is load-optimized to reduce weight without sacrificing rigidity. Plus, it also looks really cool, if you ask me.
The fork's tapered steerer tube is pressed into a slim looking aluminum crown and the OPM sports 32mm stanchions. Now, the diameter of a fork's stanchion tubes has become an easy way to classify it as far as its intentions go, with a 32mm number being what most manufacturers use for their cross-country race forks. DT Swiss, however, say that the OPM is suited to trail and all-mountain riding, and even the 150mm travel OPM fork sports 32mm stanchions.
With that in mind, I'd probably argue that the 120mm OPM O.D.L that's reviewed here should be judged against forks like RockShox's Reba and Revelation (which has 32mm stanchions) and Fox's 34 platform rather than either company's cross-country race offerings.
A 15mm thru-axle ties the legs together, and it's no surprise to see DT Swiss go with their own RWS axle for the job. It's a tool-free setup that threads in from the right side, and the spring-loaded handle can be lifted up off of the splines to better align it when it's tightened up or to clear the fork leg when you're removing it.
Riding the OPM O.D.L ForkAir Spring Performance
- Most company's recommended air pressures are too low for anyone who's riding at a decent level, a fact that's proven by many fork manuals still telling customers to run way too much sag. DT Swiss took the exact opposite approach. I started off with 84 PSI, as per their recommendation, but it was pretty obvious that wouldn't work unless I really wanted to rattle my teeth loose. I kept dropping the pressure by a few PSI at a time until the fork began to feel much, much more active, but even when I ended up at 72 PSI, which turned out to be ideal for my weight and terrain, the fork never felt quite as active and as supple as the latest from other brands.
The DT Swiss fork uses a pretty straightforward air spring system that employs a coil negative spring and, at least as of right now, no purpose-built volume adjustment system like found in most of the competition. DT Swiss are working on a volume adjustment add-on, I was told, but I doubt that I would have used it even if it was available. There feels to be a good amount of ramp-up to the fork's stroke, and I can't recall a single hard-bottoming moment that would cause concern. Full travel, yes. Smashing down onto the end of the fork's stroke, definitely not, despite running well under the recommended air pressure. Ready to huck, then. Chassis Performance
- The OPM is in the same ballpark weight-wise as a SID or Fox's 32, but there's something about the DT Swiss fork that makes it look
like it'd be even lighter than both of those. It's not, but it does feel more resistant to flexing than either and is probably closer to a heavier fork when it comes to rigidity. Given that it has 32mm stanchions, I was surprised at how precise the OPM felt, and I'd say it's more in line with a Fox 34 on this front.
The RWS 15mm thru-axle isn't quite as quick to use as other designs out there, only because you have to clock the handle to clear the lower leg until it unthreads enough to just spin it out, but we're talking about mere seconds here, nothing more. And I have to say that I prefer the solid feel to the RWS axle over a Maxle; it just feels like it would last a long, long time. Damper Performance
- It used to be that the large majority of forks were under-damped from the factory, probably in search of that plush "parking lot feel" that only means they won't work well when you're pushing hard. These days, all of the major players are pretty dialed, and the OPM certainly doesn't suffer from not enough compression control. Actually, it seems like it has the opposite issue, although friction in the damper design could also be a contributing factor. I hard a hard time getting the DT Swiss fork to feel supple, even with the anodized blue low-speed compression dial backed all the way out, set to the 'Open' mode and with relatively low air pressure in the opposite leg. It would be more on par with the competition if this was three or four years ago, but with Fox and RockShox going to great lengths to create suspension that's as smooth and active as possible, the DT Swiss fork feels a bit dated.
The lowers slide up and down the stanchions with very little effort when the fork's internals have been removed, but it turns out that there's a fair bit of friction within the damper that certainly isn't helping matters. Pushing the damper rod into the cartridge reveals a sticky stroke, and I suspect that much of that is coming from the large diameter O-ring on the spring-backed piston that slides up and down against the inside surface of the stanchion. Also, the fork had an off-putting clunk at the top of its stroke when it was locked out, something that was noticeable when I unweighted the front of the bike while climbing.
DT Swiss responds: ''We have tested this fork extensively with the input of our professional World Cup racers in Europe. The feel and progression, chassis stiffness, weight, and damper performance are all based on the needs and preferences of these riders. Each DT Swiss fork is hand made by DT Swiss, and as such follows our reputation for precise manufacturing.''Pinkbike's Take:
The three-position Open-Drive-Lock system does perform as advertised, though, as all three settings offer extremely distinctive ride characteristics. I suspect that many Pinkbike readers would prefer the non-remote version (you can swap between the two pretty easily), but the space-age-looking remote is surprisingly easy and intuitive to use when on the move.
The two levers cycle smoothly and with little effort, and the release lever snaps the fork back into action. I'm not a big fan of using remotes, to be honest, but DT Swiss have done well with theirs.
|At $1,159.00 USD, the OPM O.D.L is more expensive than all of its competition, bar the uber-expensive RockShox RS-1. And while it isn't a bad fork - it would have compared well against most of its competition just a handful of years ago - it doesn't offer the same sort of performance that can be had by spending less money. What it is, though, is a lightweight fork that many will see as being exotic, and it's best suited to a weight-conscious rider who wants something out of the ordinary. - Mike Levy|
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