Teased at Interbike last year, Formula’s new Thirty3 suspension forks are all but ready to go, and they have an all new master cylinder design for the R1 and The One brakes, plus a hot rod version called R1 Racing.
The forks are called Thirty3 because they use 33mm diameter stanchions. This makes them a bit stiffer than the normal 32mm stanchions without adding much weight. They’re available with 9mm QR and 15mm thru axle, tapered and straight steerer tubes and white or black paint. All are air sprung with custom designed seals that Formula says are super slick.
The internals were designed by Fiorenza, who has worked in motocross suspension for years with brands like Paiolo. He carried over some of the damping technology to the new MTB forks. U.S. brand manager Chris Costello says this resulted in a very simplified design.
Internally, the air chamber has both a coil return spring and larger helper spring. The helper spring handles the first 40mm of travel and gets the air chamber moving easily by pushing against it. Formula gives the fork a more linear feel and improves small bump sensitivity during compression. The return spring keeps it moving quickly during rebound.
In the right leg is a closed damping cartridge. The compression ranges from wide open to virtually closed. Even in “locked out”, there’s some give to keep the wheel tracking and avoid a harsh surprise should any drops or bumps sneak up on you.
Claimed weights are 1443g (9mm QR) and 1521g (15mm with axle), likely for the straight steerer tube versions. They’re available out of the box with either 85, 100 or 115mm of travel, but it’s internally adjustable by adding or removing spacers. The one weighed here is with a straight steerer and 9mm QR and it’s coming in a bit lighter than claimed. No official word on a 29er version, but if these prove successful, it’s a good bet we’ll see more travel and wheel size options.
To justify introducing another suspension fork into an arguably crowded market, Formula had to offer something different. The air pressure settings here, in addition to having a nice section on the label to write your preferences for quick reference, are only 60% to 70% of the settings recommended by Rockshox on their stickers. Here’s why:
This highly technical explanation from one of their engineers shows that when you rely on higher air pressures, you get more ramp toward the end of the travel (represented by the curve starting from 50psi on the left). If you could use just 5psi (bottom curve starting at 0), you’d have a much more linear curve as you moved through the travel.
By using the coil “helper” spring, it handles the first 40mm of suspension movement very easily before activating the air portion of the suspension. It’s also perfectly linear in its progression. This is represented by the darker line that goes from 0psi to meet the curve for 50psi. Overall, they claim the result is a more linear feel than if you had to rely on a higher overall air pressure. Presumably the “helper” spring negates the need for a negative air chamber, and the lower pressure is why it needs the rebound assist spring.
R1 Racing gets a new master cylinder with about a 25% bigger reservoir and a new cap and diaphragm to give it a more consistent pad contact point by handling fluid expansion and contraction better. The larger fluid volume also helps decrease sensitivity to any air in the system or when your pads start to get really low. These changes carry across to the regular R1 and The One DH brake.
What separates the R1 Racing is that it comes standard with a carbon lever blade and woven kevlar hose, too, which resists expansion better for a firmer brake feel. The brakes are sold separately from the rotors. Formula says this is to help retailers reduce overall inventory by stocking only the sizes of rotors they’ll sell and models of brakes they’ll sale, helping customers get exactly what they want.
The new two-piece rotor shown here will work with any of the systems. It has an aluminum carrier with a steel rotor. Oddly, the 140 and 160 are a bit heavier than the one piece steel rotor, but they have a better ability to cool by transferring more heat to the alloy carrier where it’s dissipated faster, and it allows the rotor to expand outward more easily so it won’t warp. Costello says it really prolongs the time it takes before you’d notice any fade. It’s available in red and black ano and possibly gold in the future. The 180 and 200 rotors are a bit lighter than their one-piece counterparts.
The RO oval piston brakes, introduced in July, offer a bigger piston area while also reducing the leverage the piston has on the brake body, which means less deflection as the pads squeeze the rotor (it won’t try to spread the brake caliper apart as much).
The piston surface is ribbed to enhance air flow behind the brake pad, and like on all their brakes the lower section of the piston drops below the pads to make more contact with the air. All this helps cool the brakes better.
