Bike Check: Viral Optimist 160

Aug 25, 2023 at 22:54
by Dario DiGiulio  
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The Optimist was instantly an eye-catcher at the Made Bike Show in Portland, Oregon, and not just because the Viral booth had their own integrated lighting in the otherwise dark showroom. The Optimist 160 is one of the more futuristic looking bikes in a sea of distinct creations, highlighting a unique construction method, progressive geometry and kinematic, and a fancy new drivetrain to boot. Hailing from Bend, Oregon, Viral is no newbie to the scene, but this bike presents a very new direction for the brand, making it quite an exciting project.
Viral Optimist 160 Details
• 29" front and rear
• 160mm frame travel, 170mm fork
• 63.5° head angle
• 485mm reach
• 440mm chainstays
• 78° seat tube angle
• 30mm BB drop
• Pinion Smart Shift drivetrain
• Viral Bikes Instagram

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Steve Domahidy, the man behind Viral, swears by the Pinion system for a variety of reasons, but the most compelling value add to this project is the simplicity it gives to the suspension calculations. Pinion's single external drive ratio gives you constant kinematics throughout the gear range, making the math quite a bit simpler. On the Optimist, Steve specced the new Smart Shift system, which uses the same mounting hardware as the prior P and C series gearboxes, but uses a more traditional-feeling trigger shifter as opposed to the mostly-maligned grip shift that Pinion was relying on previously.

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Kinematics-wise, the Optimist uses a flex stay single pivot layout to deliver its 160mm of travel, with a leverage ratio that drops from 3.04:1 to 2.44:1 throughout the travel. Anti-squat sits at about 115% at sag. These numbers are likely to change before a final production model is complete, so stay tuned for more info from Viral on that front.

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Though the overall design and fabrication is close to a final stage, Steve is reworking the linkage design to increase the frame stiffness, as the current layout is quite flexy even under light loads. The 3D-printed titanium is done using a novel process that allows for no internal fill structure, so the lugged elements are rather light and thin - V2 might have some internal bracing just to add overall rigidity.

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More photos of the Viral can be found here.



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75 Comments
  • 51 1
 woah, not normally into frames this boutique, but that's cool. That seat post mast is awesome.
  • 38 0
 Alright alright alright......you got me at gearbox. No matter how weird it looks
  • 37 0
 username checks out
  • 25 0
 As a footnote, we agree with the concerns about the belt tensioner. This is the one that Pinion has designed with the gearbox and the one that was available for the show build. We are prototyping other tensioners and will, ultimately, either use a different one or design our own.
  • 16 0
 I know this is all about the bike (which is beautiful and awesome), but this is the first time I've ever seen "Tacky Chan" tyres and I really want them (and unlike the bike itself, there's a chance I could afford to buy them)
  • 4 1
 I was at MADE and literally only looked at this bike to inspect the Tacky Chans. They are indeed nice lol.
  • 1 6
flag Balgaroth (Aug 28, 2023 at 12:17) (Below Threshold)
 Rumor has it on the DH French cups that those riding Tacky Chan basically don't pass the finish line due to punctures. #tirerumor
  • 13 0
 Some neat ideas here. The seat clamp is notably tidy-the kind of detail that makes a boutique bike special. Also-I might never buy one of these bikes, but hope the Pinion gearbox gets wider adoption. On a 35 pound trail bike-I'd take the reduced service schedule for a few watts now that the shifter design is better.
  • 4 0
 I used to have a single speed HT with a gates belt drive. Loved that easy maintenance thing.

I agree, i hope pinion continues to get better refined designs and continues to build momentum. The belt drive systems definitely have to potential to be an "almost zero maintenance" solution for people in the MTB world that abuse their bikes.

Also, this frame is gorgeous!
  • 8 0
 I'm a fan. The more of these boutique bikes that come out, the more I'm leaning toward getting one for my next bike. I'm not opposed to the belt drive on a bike. I'm not shooting for PRs on the climbs as much these days anyway.
  • 8 0
 so what happens when that guide arm gets mashed into a rock
  • 3 0
 It doubles as a bash guard, so it bashes the rock. Mine has hit so many rocks and it's doing great!
  • 1 0
 Well that would be a JRA moment and would not be qualified for warranty GREAT QUESTION THOUGH
  • 3 0
 There aren‘t that many Pinion equipped full suspension bikes out there (besides Zerode) so it‘s cool to see more options. However, if I wanted a funky linkage design with an upside down damper I’d go with the Instinctiv M.
  • 1 0
 I ride a Zerode Taniwha, but I did check in with Instinctiv before I went Zerode, and let me tell ya, Instinctiv is asking a whole lot of money for a frame made in Taiwan!
  • 1 0
 There is also Cavalerie who made the Anakin with the own gearbox Effigear
  • 1 0
 @xavier07: Sadly Effigear can't seem to meet demand, with their original gearbox, Mimic gearbox, or the frames that the their sister company produce. They lost me during COVID when they couldn't get me a bike.
  • 7 1
 Pretty rad but I’m concerned about that whole bottom bracket area getting too friendly with rocks
  • 1 0
 Not an issue, the gearbox is well protected by the bash guard/tensioner AND the gear box casing itself is very burly.
  • 1 0
 @sanchofula: If there was actually a bashguard on it I wouldn't be concerned, but it looks like the first thing a rock is going to kiss is the belt tensioner. And if you break the tensioner or belt you're SOL.
  • 3 0
 @PAmtbiker: The belt tension IS also designed as a bash gard. I ride one, and its been tested numerous times, no issues.
  • 3 0
 @sanchofula: in that case, I'm not concerned about that whole bottom bracket area getting too friendly with rocks
  • 6 0
 I remember being a viral optimist in late 2019, then I was quickly converted to a viral pessimist in 2020.
  • 4 0
 curious to see how the flex stay design with the 160 mm is going to holdup in the long run
  • 3 8
flag Notmeatall FL (Aug 28, 2023 at 9:27) (Below Threshold)
 if not going past elastic deformation in to plastic/permanent deformation, pretty much indefinetly. Way better than carbon.
  • 3 0
 @Notmeatall: have you heard of fatigue..? plenty of stuff can go wrong with deformation in the elastic regime. although I think it's fair to assume the bare minimum of engineering was done to ensure the flexstay will last.
  • 1 0
 @alienator064:

When carbon handlebars first started to appear, Klein decided to make some. The other companies were seeing failures at 10k-20k cycles on a machine. Klein's bar went to 200k cycles, and they stopped the test.
  • 6 6
 @alienator064: have your heard of endurance limits? titanium is a material "with a knee" which means it has infinite cycles and will never fatigue. Under the endurance limit. Alu does not have "a knee" which is why you probably correlate metal frames with fatigue.
  • 5 0
 @mariomtblt: titanium definitely fatigues! Can’t remember all the details but my dissertation back at uni was in material science, specifically on ti6al4v and I know it for sure had fatigue cycle limits. As far as I’m aware I don’t think any material can avoid fatigue
  • 1 0
 @mariomtblt: is that true for the titanium alloy used in 3d printed "titanium"?
  • 1 0
 I'm equally curious to see how you can deliver that amount of travel with a flex stay and still have the bike be stiff where it needs to be (i.e. laterally, torsionally). I had troubles with my stumpjumper where the rear tire would rub against the seatstay under lateral forces.
  • 2 0
 @mahargetan: you can see with how they designed the titanium flex component to be very flat and wide, so that it is vertically compliant but laterally stiff. it would not be a very torsionally stiff design however.
  • 2 0
 @mariomtblt: and how close is the endurance limit to the yield stress? if the endurance limit is like 10 kPa then that's kind of a useless property.
  • 3 0
 @mahargetan:

My brother showed me a sample of composite from his airframe repair course. It was a tiny, rubbery tab that could be very easily twisted, but I could not bend it in half with all my strength.
  • 2 0
 @alienator064: youre right, I have no idea. flex stays aren't scary though. not from a reputable company anyways
  • 2 0
 @mariomtblt: very true. the analysis to determine how long flex stays will last is pretty simple, there's no doubt that a company that could design a bike frame can design a flex stay that would easily last the lifetime of the bike.
  • 6 0
 @Joebohobo: All materials will eventually fatigue, but the fatigue limit for Ti-6Al-4V (guessing on the alloy here, but that's the most common one used in 3D sintering applications) has a fully reversed fatigue limit of ~410 MPa / 60ksi. Considering the application, it would be safe to assume this link has been designed to keep stresses under that limit, which in turn should result in an essentially indefinite lifespan for it's purpose- ie into the billions of cycles.

Even the fatigue life of aluminum bicycles (which have no fatigue limit) is vastly over hyped by the cycling community- any decent frame design that's been properly manufactured will outlast it's rider unless it's been totally thrashed.
  • 1 0
 @Joebohobo: Steel typically has an (infinite) fatigue strength of 50-60% UTS.
  • 1 0
 Titanium Flex stays are easily designed. Under certain conditions the Titanium does basicly not fatigue
(yes there are Phenomena which lead to fatigue und low stress but that would not play a roll in a bikes frame
(a well designed titanium flex pivot could outlive the rest of the bikes by an order of magnitude))

Also flexpivots have fewer parts, cant get dirt in them, dont have Bearings which might need maintanance or be replaced(pitting might come to mind) so its possibly the more reliable solution
  • 1 0
 @alienator064: depends on many factors but a rough value (should be taken with a grain of salt) around 410Mpa at 10e9 cycles (for Ti-6Al-4V)(around 1/2 of yield strength)
  • 1 0
 @Joebohobo: I'm not a rocket scientist but I understand SLM 3D printed titanium has about half the fatigue life of standard forms...whether that is significant I don't know, but if I was swinging a leg over it, I'd certainly want to know!
  • 1 0
 Short answer: Perfectly fine.
  • 5 0
 Pink is an underrated color.
  • 4 0
 I saw this bike in person yesterday at MADE in portland and I cannot overstate how stunning it is in person.
  • 1 0
 Weight? Super curious... not that weight is the only thing that matters, but it is helpful for comparison.

I'm more and more interested in a gearbox bike, both for suspension performance, and ease of maintenance... but I think I'd want a chain driven one? I've heard too many horror stories of broken or squeaky belts.

Is there a reason they are mostly belt drive? I was under the impression that chains are far more efficient and easier to replace.
  • 2 1
 Is is me or are frame designers rarely fully-capturing bearings at linkage pivots anymore? And not maximizing bearing spacing, like at the main pivot, then wondering why the rear is flexy? I realize the frames are stress analyzed but yeah
  • 5 1
 I would destroy that belt tensioner device in 5 minutes...........
  • 2 0
 Based only on appearance, I've always thought this was weak link on Pinion full suspension frames. I think Zerode bikes with the drive belt are very interesting but would never go this route until they come up with a better belt tension solution.
  • 2 0
 Same here...I would rather they put the belt tensioner ANYWHERE else along the driveline.
  • 1 0
 @y0bailey: I’ve been riding my Zerode hard in BC for over 6 years now and have never hit that thing….
  • 3 0
 No you wouldn't, I a big guy who rides a lot of rock, bashing rocks is what I do; you should see my crank arms, and that tensioner is also designed as a bash guard; I ride a Zerod Pinion.
  • 2 0
 Have you tried improving your riding?
  • 1 0
 @Moosemandible: I routinely try to hop on/over the highest things I can find.

My taco looks like it was run through a meat grinder...but through a shitload of practice I can hop onto the top of a picnic table.

I'm not going to stop showing off that skill I worked hard for, and I'm not buying a bike that can't handle it when I f*ck up.
  • 3 0
 I've ridden my Zerode all over the US for 6 months and have mangled two of the belt tensioners. Second time was even with Zerode's JRA guard, which really just protects the belt from taking hits against the chainring. And at $175 USD, the tensioners are not cheap. There really needs to be a better solution.
  • 1 0
 @tdeems: wow.... never heard of these issues. Bummer
  • 1 3
 @tdeems: Dude! I ride my Zerode Taniwha MX hard as hell in all kinds of Southwest rocky gnar and though I've hit plenty of rocks, I have yet to ruin one after nearly a year. Unless you're doing crazy trials or you crash a ton, that belt tensioner is pretty safe.

I'd say it's a user issue ...
  • 1 0
 The % of efficiency loss on belt drive vs chain drive is a small piece of the pie: tires, suspension design, drive train, my own strength...
  • 3 1
 I've always wondered what that % looks like when a conventional drivetrain is covered in mud, which makes up 70% of riding in the PNW. Do the numbers suddenly flip, with gearboxes more efficient?
  • 3 0
 @Mtmw: Yes, see Cycling About youtube channel for technical details
  • 2 0
 Can someone explain how that rear triangle is going to survive? Seats stay looks to snap going off a curb.
  • 1 0
 The flexy part of the stay looks a little on the fragile side. That area gets hit hard during a crash. Also, flex stays on a 160 bike?
  • 2 0
 This bike is all the cool techy, niche ideas in one bike. I love it.
  • 1 0
 How long does it take printed Ti to fatigue? printed parts dont usually do well there. Will it snap in 3 years?
  • 2 0
 looks amazing!
  • 1 0
 Is that a prototype shock???
  • 2 0
 Appears to be a normal super deluxe with custom decals.
  • 1 0
 I hope it isn’t optimism that’s holding that seatstay together.
  • 1 0
 additive lugs bonded construction bikes...so hot right now
  • 1 0
 A comment section love letter in the flesh
  • 1 0
 I will go gearbox before I ever go wireless shifting.
  • 1 0
 Anathema, the Optimist.
  • 1 1
 Needlessly complex and unnecessarily unique construction.
  • 1 0
 Awesome work Steve.
  • 1 0
 looks snappy
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