Viral Bikes founder Steve Domahidy is a giant fan of the Pinion gearbox, and also you’ll discover it his titanium hardtails…and this new full suspension enduro mountain bike, too, which blends two supplies with loads of distinctive concepts about how one can use them.
The Viral Optimist 160 bonds UD carbon fiber tubes between 3D-printed 6/4 titanium lugs made with a sophisticated, high-power EBM course of, with the seatstay lug made to flex. That, plus the Pinion’s single “ultimate drive” gear, permits it to have a quite simple single pivot design, however obtain a whopping 160mm of journey with kinematics outlined by a linkage.
Beginning with the body, Domahidy says their EBM (Electron Beam Melting) course of each sinters and warmth treats the titanium because it prints the components. He says most 3D-printed titanium makes use of DMLS sintering with a 400-500W laser, presumably as much as 1000W. His, nevertheless, is 3000W, and it strikes magnetically moderately than with belts and slides.
This design lets it transfer quicker and warmth the fabric to 700ºC (1,292ºF), which he says is the annealing temperature of titanium, which means it’s each created and warmth handled in a single step. The profit is that post-production processing is simplified, and since they’re 3D printed, they’ll customise the geometry, cable routing, and different options based mostly on buyer requests.
The bike is a collaborative undertaking with Pinion, using their new digital SmartShift system. The unique Pinion gearboxes, which sit on the crankset, used a dual-cable design with a twist shifter that wanted to tug cable in both path to impact a shift.
The brand new Pinion SmartShift makes use of digital shifting, so there’s a extra acquainted set off and no must run two mechanical cables to it. It’s powered by a self-contained rechargeable battery, with the shifter wire following the brake hose as much as the handlebar. Presumably, the 3D-printed BB/Gearbox junction might be made to suit Pinion’s new e-bike motor-with-gearbox unit, too, turning the Optimist into an eMTB (although they’d want a much bigger downtube to deal with the battery, the modular lugged development ought to make this straightforward).
The suspension works through the use of flex stays, however not the place you’d suppose. Most bikes utilizing a pivot-less rear triangle design the carbon seatstays to flex, however right here it’s the titanium lugs close to the axle.
The flat part above the axle flexes, and regardless of appearances, it’s a double wall design with about 2mm of open area inside. Domahidy instructed us it’s solely flexing lower than 2º all through the whole 160mm of journey, so it’s not a lot.
The opposite advantage of the 3D printed lugs is that they’ll print the decrease part to suit any shock the client desires, coil or air, so long as the eye-to-eye and stroke size works with the design. A snap-on cowl plate in entrance of the shock’s trunnion mount allows you to entry rebound and compression knobs.
The kinematics are designed round a 15% progressivity in leverage ratio, “beginning out at a bit over 3:1 and ending at 2.44:1, giving superb small bump compliance and backside out help.”
Domahidy says the massive benefit of the Pinion system is that the entire gears are inside, which suggests there’s just one chainring and one cog, so the chain’s relationship to the pivot location by no means adjustments. This implies anti-squat is identical in each gear, so the bike may be absolutely optimized with out having to compromise to work throughout an enormous cassette.
It additionally takes the burden of a cassette and derailleur off the again, so the suspension can transfer extra freely. Lastly, and particularly mixed with the Gates Belt Drive, it’s very low upkeep. This bike will get one based mostly on the Pinion C.12, which has 12 speeds and an enormous 600% gear vary.
It’s a 29er entrance and rear, with ample clearance for two.5″ tires (a 2.6″ would possibly match, relying on tread). It holds one bottle cage on the downtube, and a second mounting level beneath the highest tube matches a 2nd cage or different two-bolt equipment.
Whereas the ultimate geometry and sizes are being finalized, this one is a measurement medium and has:
- 440mm chainstay size
- 63.5º head tube angle (with a 170mm journey fork)
- 78º seat tube angle
- 485mm attain
With out the Pinion gearbox hooked up, body weight is round 5.5lbs (2,490g) with a Rockshox shock as proven. Supply is predicted in early 2024, and pricing is TBA till it’s nearer to manufacturing.
