Formula Belva Fork
Travel Options: 170 and 180 mm
Wheel Size Option: 29’’
Available Offset: 43 mm
Stanchion Diameter: 35 mm
Stated Weight: 2,370 g / 5.22 lbs
Stated Axle-to-Crown Height (180 mm travel): 585 to 595 mm
MSRP: €1,850 / $2,150 CAD (USD pricing TBD)
Intro
The bike world has mostly settled on using dual-crown forks for DH bikes and single-crown ones for everything else these days. Over the years, though, there have been a few attempts to make lighter-weight dual-crowns that are versatile enough to use outside of lift-served trails, from the RockShox SID XL of the late 1990s to the Specialized Future Shock, Mojo MORC 36, and others.
And, to their credit, there are some very real advantages to a dual-crown layout. For one, it’s much easier to make a fork stiffer fore-aft when you have a second crown to work with. Dual-crown forks can also adjust their ride height independently of their travel setting (via bolt-on crowns), and direct-mount stems are often lighter than their conventional counterparts, don’t run the risk of slipping or coming out of alignment, and are often stiffer and more precise in how they steer, too.
I’ve been calling for companies to offer lightweight, Enduro-oriented dual-crown forks for years now, and Formula has (finally, after years of prototypes being sporadically spotted) answered with their new Belva fork.
Here’s how Formula describes their rationale for the Belva:
“With bikes becoming more capable and e-bikes gaining in popularity, your suspension needs to work harder than ever. As engineers, we believe the best solution to building a stiffer, long-travel fork is by using a dual-crown design.
Most fork flex occurs at the crown steerer unit (CSU), regardless of stanchion size. A dual-crown design avoids this — and the associated creaking — by centering the stiffness around the headtube.
Absolute stiffness is not everything, though. Using our proven Selva lowers, the Belva can flex where it is most needed. With the dual crown and a direct mount stem, you can have laser-sharp steering and confidence-inspiring stiffness, combined with trail-hugging traction and comfort.”
So, that’s their answer to the “why” behind the Belva. What about the “what” and “how”? Let’s get into the details:
The Design
There’s a lot of interesting stuff going on with the Belva, beyond just its dual-crown layout. Many of its details are shared with Formula’s single-crown Selva fork, rather than being brand new for the brand. But the Belva still stands out from the rest of the market — so let’s see what they’ve come up with.
Chassis
We’ll start with the chassis: the Belva shares its lowers (and thus its 35 mm stanchion diameter) with the Formula Selva, but the Belva gets a dual-crown layout with forged crowns and a tapered steerer tube. The latter aspect is unlike most dual-crown DH forks, which stick with a straight 1.125’’ steerer tube. The Belva’s crowns are notably svelte-looking, with a lot of cutouts in the upper crown in particular, and despite the dual-crown layout, Formula’s stated weight for the Belva is just 2,370 grams — comparable to that of the single-crown RockShox ZEB, Fox 38, and EXT Era, for example.
For now, Formula is only offering the Belva with a 110 x 15 mm axle and compatibility for 29” wheels, despite having options for 27.5’’ wheels and / or a 20 mm axle on the Selva. The Belva gets 43 mm of offset and is offered with 170 or 180 mm of travel. The Belva’s axle-to-crown height is 585 to 595 mm at 180 mm of travel (and 575 to 585 mm at 170 mm travel, adjustable due to the dual-crown layout).
That’s roughly in line with most modern single-crown forks at the same travel setting; e.g., a 180mm-travel 29er RockShox ZEB comes in at 596 mm, and a Fox 38 with the same specs is 593.7 mm. That makes the Belva a bit taller (relative to the amount of travel) than most dual-crown DH forks, which tend to run a little shorter than single-crown ones at the same travel. Given that Formula is marketing the Belva specifically as an Enduro fork, that makes sense — it’ll swap onto a bike that’s meant for a 170- or 180mm-travel single crown without changing the ride height much, while affording a little room to tinker.
The Belva is offered in black or Formula’s signature purple, and its lowers get post-mount tabs for a 180 mm brake rotor, which Formula condones adapting up to a 220 mm one if you’re so inclined. The Belva’s axle uses Formula’s “Integrated Locking System” (ILS) quick-release lever, which can be removed from the axle if you’d rather do things with an Allen wrench and save a few grams.
Damper
The Belva’s damper uses a similar design to that of the Selva, just reconfigured for the dual-crown chassis. It gets an external rebound adjuster, a single compression knob, and a lockout lever with adjustable threshold for how firm the lockout is. The compression knob is tool-free with 12 clicks of adjustment; the rebound knob gets 18. The threshold dial for the lockout uses a tooled adjuster on top of the fork leg, next to the compression knob and lockout lever.
It’s not super common to see a lockout lever on a longer-travel fork these days, but it’s not unheard of either; where things really start getting interesting is Formula’s “Compression Tuning System” (CTS).
In short, the Belva (and the Selva) feature swappable compression-valve assemblies that allow the user to swap in one of eight different base tunes to fundamentally alter the damper performance.
In very broad terms, Formula offers CTS cartridges with two general compression damping curve shapes. There are five options for a lightly digressive curve with differing levels of overall damping (purple, gold, orange, green, and electric blue, in order of lightest to firmest damping); those get more linear as you work your way up in order of overall firmness. And then there are three with a substantially progressive damper curve (silver, blue, and red).
[By a “linear” damper curve, we mean that the amount of compression damping increases in a more or less straight line as the speed at which the damper is compressing increases; a “progressive” curve means that the damping force increases more rapidly at higher shaft speeds than it does at lower ones. A “digressive” curve — as seen most notably on the purple and gold CTS valves, below — builds damping force relatively quickly at lower shaft speeds, but the rate of increase tails off at higher ones.]
You can see Formula’s published damper curves for the various options here:
Formula says the swap can be done in about five minutes, without even removing the fork from the bike, and without needing to bleed the damper. You could even do it trailside if you really want to, though they don’t recommend that, due to the risk of getting dirt in places it doesn’t belong. Realistically, it’s probably more of a swap that folks will make when finding their preferred initial setup, or maybe when changing riding locales to somewhere with very different terrain, but it’s an intriguing way to make (semi) custom valving more accessible for more folks.
[Formula has a video demonstrating the swap if you’re curious. It also opens with the wildest safety disclaimer I’ve seen in recent memory. I won’t spoil it beyond that.]
The Belva ships with the gold CTS cartridge installed; additional cartridges are available for about $65 each if you want to experiment.
Spring
Formula offers the single-crown Selva in both air- and coil-sprung configurations but has once again paired the offerings down for the Belva, which is offered with an air spring, only.
Formula describes the Belva as using a “single air” spring. This is in contrast to their “dual air” Selva R, with independently adjustable positive and negative spring pressure, or the “triple air” Nero R DH fork, with a dual positive air spring and adjustable negative one.
Its “single air” arrangement means that the Belva uses a coil negative spring rather than a more typical self-equalizing air one. They’ve been using a similar layout in the Selva S for a while now, and say they’ve hit on a design that works well for folks at a wide range of rider weights (and thus air spring pressures).
The Belva also uses Formula’s “Neopos” volume spacers, which are conceptually similar to those used by Fox and RockShox, among others, except that the Neopos spacers are made from a compressible foam material, rather than rigid plastic. The idea is that the Neopos spacers take up more volume inside the air spring earlier in the fork’s stroke when the pressure in the positive spring is lower, and then the Neopos spacers compress deeper in the stroke as pressure on them increases, reducing the amount of ramp-up effect deep in the travel as compared to a standard rigid volume spacer.
The goal is to offer more midstroke support without making the fork keep ramping up deeper in its stroke, not unlike the thinking behind dual-positive air spring designs. (Check out our review of the Manitou Mezzer Pro for a rundown on what we’re talking about there.) But there’s another, more subtle difference in how Neopos works.
In short, air springs don’t perform entirely consistently depending on how fast they’re compressed — unlike coil springs, where the force needed to compress them is just a function of their displacement. As air is compressed, it heats up, which in turn increases the pressure in the system; that effect is moderated at lower compression speeds and increases at higher ones. An air-sprung fork is actually stiffer if you compress it quickly than if you do so more slowly, and therefore also returns more energy on rebound after a fast compression than on a slower one.
Formula says that the Neopos spacers moderate that effect by expanding at a constant rate, no matter how quickly or slowly they were compressed in the first place (like a coil spring, rather than an air one), making for a more consistent and predictable rebound feel.
Warranty
The Belva is covered by Formula’s new 10-year support promise — a guarantee that they’ll offer on parts and service for everything in their lineup for at least 10 years. Everything they’ve made since 2017 is covered by the support promise, and the Belva also gets a two-year warranty, which can be transferred to subsequent owners.
Some Questions / Things We’re Curious About
(1) How does the Belva chassis feel, given its dual-crown layout and impressively low weight?
(2) What about the Belva’s spring and damper designs? We haven’t ridden any of Formula’s current fork offerings, so how do they perform on the trail?
(3) And will we see more widespread adoption of dual-crown forks for Enduro bikes, especially as eMTBs become more common? This question pertains both to other fork manufacturers following suit, and to frame companies condoning running dual-crown forks on their non-DH bikes.
Bottom Line (For Now)
We’ve been very excited about the Belva ever since we first caught wind of the prototypes back in 2021, and we’ve been hoping for more options for lightweight Enduro dual-crown forks for a lot longer than that. So, we’re glad to see Formula bring their take on the genre to market. We’re working hard to line up a Belva for review and will have a lot more to say about how it stacks up if and when we’re able to make it happen.