DVO Diamond D1 Mountain Bike Fork Review: Unique Adjustments for a Velvety Smooth Ride

The DVO Diamond D1 mountain bike fork looks like every other long travel fork, until you flip it upside down.

We’re now able to crack the throttle open a little on the trails here in Italy after an extended quarantine, and it feels magical to get outside and push harder on the bike again. I rode the Diamond D1 fork from DVO a wee bit before lockdown, and during plenty of back yard wheelie sessions, but having the chance to push it toward its true intentions revealed an entirely different piece of suspension performance gear.

On first inspection, the Diamond D1 looks like most other 29er 160mm enduro forks. It has 35mm stanchions, and external high-speed and low-speed compression and rebound adjustments. Sound familiar? However, if you flip it upside down you’ll notice a bolt head in the non-driveside leg that adjusts preload on the coil negative spring. You read that right, the fork has a coil negative spring, in place of a negative air chamber. Turning the OTT bolt one direction will soften up the fork’s initial stroke, and, as expected, the opposite direction firms up those first few centimeters of travel.

The fork I received weighs around 2150g, which is slightly heavier than some other forks of the same size and spec. Since all of the DVO engineers are former Marzocchi employees from the brand’s freeride days, I have a feeling that little extra weight went into the right places.

Setup and tuning

While the initial setup with this fork was relatively easy, it required a fair bit of fine tuning once I was able to start pushing it harder and looking for its limits. I pumped in the maximum recommended air pressure for my weight, and kept adding 5psi until I found the support I was after. The sweet spot for my riding style ended up in line with the pressure number that DVO recommends for a rider about 20lbs heavier than me, which isn’t dissimilar to other forks I’ve tested. Suspension companies have to offer a pressure and damping range that works for most riders, and their suggestion won’t please everyone’s flavor palette.

Then on to DVO’s proprietary OTT (Off The Top) adjustment. The brand says that this coil negative spring preload adjustment “allows the rider to adjust the initial sensitivity of the fork. Typically, a firm feeling fork (higher air pressure) will have poor or no small bump sensitivity. DVO has solved this problem with OTT.”

Since I was aiming for a more supportive feel with the Diamond D1, I left the OTT settings dialed all the way out for the majority of the review period. I did try the fork with a few full rotations of the OTT bolt to see how it felt, and it very clearly softened up the initial stroke. There’s a glowing benefit here that heavier or more aggressive riders who run higher pressure will likely appreciate, as will folks who simply prefer a super plush squish up front.

The paint work on the Diamond D1 is some of the best I’ve seen.

On the damper side, I started with the recommended settings, and fiddled around from there. I ended up with the rebound a couple of clicks faster than the dial’s half-way point, three clicks of high-speed compression, and two clicks of low-speed compression. These settings make the fork feel slightly harsh for general riding, but at speed it really comes alive and it’s able to sustain larger hits well, followed by quick recovery. It hangs high enough in the travel under heavy braking that I have rarely added more low speed compression, and its traction performance is on par with other forks with similar settings.

Now for the rub. There are no volume spacers made for the Diamond D1. Even while running the fork with a pressure that could be considered “over sprung” for my weight, it bottomed out with an alarming “clang” on several occasions. We have some midsized huck-to-nowhere jumps on my local lunch lap, and the Diamond D1 was no match for their human catapult character. While I could have added high-speed compression, the fork already felt felt somewhat harsh on chundery trails at lower speeds and I didn’t want to increase to that sensation.

I asked DVO customer service what I could do about this issue, and after confirming that my setup was good-to-go this was their response:

Since we don’t make volume reducers for the Diamond and don’t recommend using other spacers, you must add 5-10cc’s of 7.5wt fluid to the air side to create more progression. This method eats up volume and does the same thing reducers do. Simply remove the valve core and use a syringe to insert the fluid.  Make sure to avoid Rockshox and regular Maxima fluids (Maxima Plush is ok) as they make our seals swell. We like Motul, Motorex, Silkolene, RSP, Pro Circuit, WPL and Spectro Fluids. 

Since I don’t have a Schrader valve tool or 7.5wt suspension oil around, I didn’t test the suggested volume reduction method. If I were looking for a new enduro fork for my bike the Diamond D1’s lack of a quick and simple air volume reducer swap would be a deal breaker.

Bump munching

As stated above, this fork is a treat at speed, despite the bottom out issue. Its compression and redound range offers fantastic support in every other situation. On slower technical segments of trail the tune felt a little unforgiving, but at enduro race pace it smoothed out the rough stuff just as it should. When I did add a few turns of the OTT bolt it felt better in the über slow and chunky stuff, but the adjustment also gave it a spongey and less precise character at speed. If I lived in an area with more slow-tech I would definitely play with the OTT preload to dial in a more universal tune.

Riders who enjoy the “magic carpet” effect of a super supple fork will love the OTT adjuster bolt, located at the base of he rider’s left fork leg. With up to fourteen full rotations of negative spring preload adjustment, it can be clicked into anyone’s buttery liking. After turning it by two full rotations, it made every rock and brake bump feel flatter, while it also improved grip on bermless turns where there is less compression to create traction.

On the way up hill, clicking the low speed compression closed gives the Diamond D1 a nice solid stance that’s sweet for climbing out of the saddle on smoother surfaces. Riders will need to record or recall their compression settings with this fork, as it is possible to accidentally toggle the high-speed compression knob while spinning the low-speed. In fact, the easiest way to adjust the high-speed is with the low-speed lever.

I arrived home with 3.25% less mud on my goggles. This fender could be 3X larger.

If you ride like DVO sponsored athlete Rémy Métailler, or your own version of as “fast as possible,” this fork will take a little more time to tune than some. The chassis and 35mm stanchions are plenty stiff, and the simple bolt-through, 15mm axle offers ample rigidity at the far end. Finding the acute point of balance between confident support at speed and a fork that’s too harsh is a little more difficult with the Diamond D1, but it’s certainly possible. Folks who are looking for a burly race fork will likely be happy with this one, after some clicking and pumping, while anyone who likes to huck-to-flat will likely need to purchase some 7.5wt suspension fluid to find the performance they’re after.

Lastly, what’s with the micro fender? While it’s nice to see fork manufacturers considering the fact that some riders want a fender up front, and don’t want to wrap their recent $1,000 purchase in zip-ties, the piece of plastic that DVO sends with the Diamond D1 is more of a placeholder than it is a fender. It doesn’t cover enough tire to keep any mud or water out of your eyes, nor is it wide enough to keep the stanchions any cleaner than they would be without it. The upside is that there are three bolt holes on the backside of the bridge where Diamond D1 owners can get creative and mount their own zip-tie-free fender.

Price$749.00 – $1,024.00
Weight Roughly 2150g
Internally adjustable travel 27.5″ 150-170, 29″ 140-160
External adjustments High and low-speed compression, rebound, OTT (Coil negative preload)
Offset options27.5″ 37mm or 44mm, 29″ 44mm or 51mm
Stanchions35mm tapered alloy
Brake mountDirect mount 160mm (180/203 w adaptor)
Color optionsBlack, green, blue

Final word

In closing, I’m going to go with the classic question, “would I recommend this fork to a friend?” The answer is largely yes, though it depends on the friend. If they were a heavier rider who could benefit from the initial stroke tune that the OTT offers I would likely say “go for it.” If the friend was a lighter rider who wants a highly tunable fork with a feathery smooth initial stroke, the reply would be the same. In fact, for most of my trail friends, I would say “it’s a well designed suspension component, and if you dig it then it’s the right fork for you.” For the narrow subset of riders who like to go fast and take chances on the regular, particularly off the ground, I would suggest checking out some other forks before committing to this one. I wouldn’t be surprised to see an updated Diamond D1, including a selection of volume spacers and a legitimate fender, in the near future.

To give it one last boost in the positive direction, the DVO Diamond D1 is fully serviceable by any home mechanic with the right tools, and all of the necessary replacement and maintenance bits can be purchased directly via the DVO website, or through a local dealer. This makes it easier and less expensive to keep the fork in tip-top shape, without waiting in a repair queue.

The Diamond D1 is available in blue (pictured), green, and black, with an MSRP of $749.00 – $1,024.00.

⭐️ Find the Canyon Spectral AL 5.0 at Canyon.

Thanks to Italian DVO distro, 4Guimp, for loaning us this fork for testing and review.

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