2 Unique Mountain Bikes from the Enve Builder Roundup

Jul 13, 2023 at 11:14
by Alvin Holbrook  
This year brought together 23 custom frame builders and brands to the Enve headquarters in Ogden, Utah to showcase the best that each builder could put together. The majority of the creations were road or gravel bikes, but there were also two mountain bikes that stood out.

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Viral Bikes

Let us introduce you to Viral Bikes‘ first full-suspension bike. The Viral Optimist 160 featured 3D-printed titanium lugs with custom tubes to create a custom-geometry mountain bike. This isn’t Domahidy’s first time building a bike brand: he helped build Niner Bikes and its unique CVA Suspension as well. A lifetime of work on CVA guided him to what he feels is “the cutting edge of mountain bikes.”

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Of note in this image: the bolted-on seatstay bridge is how Viral can install and remove a Gates belt drive without needing a breakaway point in the seat stay or chain stay.

The Optimist 160 has a whole lot going on, but there are two core tenants here: use of the new Pinion SmartShift electronic shifting gearbox, and custom geometry to suit a rider’s fit and riding style.

Viral Bikes founder Steve Domahidy touts three main benefits of designing the Optimist 160 around a Pinion gearbox. No derailleur removes two pounds of unsprung weight at the back of the bike. The back end of the bike is “wildly more active” as a result and far more tuneable as well. Additionally, anti-rise numbers are the same regardless of which gear you’re in. And as a bonus, there’s no pedal kickback from the Pinion gearbox either.

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The Optimist 160 will come exclusively with the SmartShift gearbox. Rejoice, Gripshift haters!

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3D-printed titanium generally has a set of lattices inside that add strength to the structure. Viral uses Electron Beam Melting (EBM) that prints parts at 700 degrees Celsius, the annealing temperature of titanium. As such, the titanium printed parts are already heat treated as they’re produced.

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The Optimist 160 uses a single-pivot rear suspension with a flex stay out back.


Between the belt and controlling the final drive ratio, Domahidy says there’s no need to further deaden the bike or add complication to the frame. Titanium’s inherent flexiness and resistance to fatigue should aid in that performance as well.

Anti-squat at sag is about 115 percent, according to Domahidy. The suspension is said to be tuned with small bump compliance in mind, with about a 15% progression in leverage ratio, starting out at a little over 3:1 and ending at 2.44:1.

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The details are killer. The inner custom bike geek within me loves how the rear brake caliper is elegantly integrated into the rear triangle.

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3D printed 6/4 titanium lugs, carbon tubes, and a whole lot of love. As currently constituted with the SmartShift gearbox, Rockshox Zeb fork and Super Deluxe shock, and Enve M7 wheels, the Optimist 160 weighs in at about 35 pounds (15.9 kgs).

Expected availability of the Viral Optimist 160 is early 2024, with a turnaround time of about two weeks. More information: www.viral.bike




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Chumba Bikes

Chumba Bikes is a small company based out of Austin, Texas, spearheaded by Vincent Colvin. Steel and titanium are usually their mediums of choice for building a frame, all with an eye toward functionality and intention in their design. Chumba brought along a custom-painted Sendero hardtail paired with a color-matched ENVE rigid carbon fork. Chumba touts its frame’s capability in the lightweight trail segment, but many end up using theirs for bikepacking.

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Just about every Chumba features sliding dropouts for use with either geared or singlespeed drivetrains. Singlespeed ain’t dead, folks.

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This Sendero received a custom finish that extends to its stem, bars, and even integrated fender.
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The Enve Mountain Fork features a flip chip at the dropout to modify the bike’s handling. We love just how the bolts are precisely painted in a half green, half blue.


Photos: Troy Templin


Want to ogle even more custom bikes? The road bike gallery is over on Velo at this link, and the gravel bikes can be found here.

Author Info:
alvin-at-velo avatar

Member since Mar 1, 2023
1 articles

112 Comments
  • 76 2
 If you were in the market for a $10,000 bikepacking bike you would be very excited about this article
  • 23 0
 Where’s incognito robin at?
  • 7 0
 @panthermodern: was he also abducted by aliens, or was he the alien?
  • 18 0
 @DirtBagTim: it was Levy all along!
  • 7 1
 I definitely think that Chumba is a Badass bike
  • 5 0
 @ihsik: ♪♫ I Get Knocked Down ♪♫
  • 2 0
 I'm sure they got knocked down by this criticism, but can they get up again?
  • 2 0
 @stovechunin: that’s a strange tune to be associated with a price tag like that
  • 1 0
 in al fairness the 1st one would be a DOPE trail bike. better than 99% of bikes out there in terms of tech, looks etc..
  • 63 4
 I heard somewhere recently the gluing Titanium and Carbon together doesn't end well .... ya, ya...I will see myself out.
  • 7 0
 I’m out of the loop, was there an article or event recently where this was an issue?
  • 51 0
 I'm sub'd to this thread.....
  • 29 0
 @Takaya94: I'm imploding to know
  • 16 0
 @Takaya94: A Titanic one.....
  • 36 0
 Deep down we all know.
  • 15 0
 @RadBartTaylor: Ha damn ok, I get it now. I'd say this one when right over my head but sounds like it actually went below it ha.
  • 2 14
flag joelsman (Jul 13, 2023 at 16:05) (Below Threshold)
 I think that is aluminum and carbon, not titanium. Raw carbon and raw aluminum chemically react. Epoxy covered carbon is fine with aluminum. Atherton bikes uses same as this bike.
  • 9 1
 @joelsman: I think they're being a little implosive and underwater with their meaning here. It took me a bit to get it too. Wink
  • 1 0
 @ViralBikes: thank you. I now get it and all too soon.
  • 3 0
 Anything can work better or worse, it just depends on how it's done, how suitable it is to the desired application etc. And in the case you refer to, the problem wasn't even the gluing specifically, but the use of an ill-suited material like carbon. So don't ride carbon bikes or you will die.
  • 1 0
 @hal9k: We definitely need to see a huck to flat report on that viral bike.
  • 27 0
 Anti rise is something I get when looking at these bikes
  • 2 1
 So you're less than half full?
  • 13 1
 After going for a ride on a derailleur e-bike, as well as seeing pros throw weights on bikes, i think the increase in sprung weight that comes with a gearbox or e-bike actually does significantly more for suspension feel than the decrease in un-sprung weight. I believe that gearbox bikes probably feel great, i just think our understanding of why that is the case is a bit off.
  • 5 0
 www.bikeradar.com/news/add-weight-go-faster-orange-bucks-the-lightness-trend

Of all the bikes out there that could possibly benefit from added ballast, I don't think Orange needed any more weight.
  • 6 0
 @hamncheez: I ride a homebuild steel fully (check out my photos). It would certainly be nice to have a little less weight (its not too bad tho, just under 10 lbs frame with shock) for climbs, but i tell myself it helps a bit on descents Razz , and hope the recent fad of the advantage of extra weight has merit, tho i'm on the fence.
  • 4 0
 Get working on yer beer bellies folks!
  • 2 0
 @ripcraft: Ha, 10 pounds is pretty good! Thats how much a Marino frame weighs in the larger sizes.

It would be interesting to see if a 10 pound steel frame rides any worse than a light carbon frame, but with weight added super low around the bb (I get thats what they did in the video in the article I linked above, but I want to experience that myself)
  • 3 1
 To a point... most of the weight of an e-bike is sprung weight... but I sure as hell like riding down on my 36 lb enduro vs a 50 lb e-bike. It gets to a point where slowing down, picking up the bike, jumping and moving the bike around are all much worse on a 50 lb bike vs a 36 lb bike. Even fast cornering... that 50 lbs always wants to stand up and throw you out the outside of the corner vs the 36 lbs.
  • 2 0
 @hamncheez: I suppose i'd accept a carbon bike to test your theory Razz

I'm actually keen to try a bike with a steel front triangle and a carbon rear end. A lot of hype for steel bike focuses on compliant stays but i actually think most of the benefits of steel fully's are in the compliance of the skinny tubed front triangle, somewhat buffering the handlebars from what the rest of the bike (other than the fork/front wheel) is dealing with.
  • 3 0
 @ripcraft: I've been prototyping titanium bikes for this reason too, evaluating front-center and rear-center flex. My next step is I think I'll buy some DIY carbon kits and add carbon layers to the chainstays, and then the downtube around the BB to see how that affects things, like specialized did

ep1.pinkbike.org/p5pb17427775/p5pb17427775.jpg
  • 1 0
 @ripcraft: with garages like that, who needs houses? I actually think you do significantly believe that. Strap some lead to your steel and get busy. The cutting edges of the tenants of optimism demand it
  • 1 0
 @hamncheez: Why? Oranges are quite light.
  • 2 0
 @ripcraft unsprung/spring mass is never thought about in isolation, it is the ratio of sprung/unsprung that matters. So the gearbox improve such ratio quite dramatically since if decreases unsprung mass while adding sprung mass. EBikes feel good because they add a lot of sprung mass which allows to shift the ratio despite no reduction in unsprung mass. But from real mtb you can't add 4kg to your frame so shifting exiting weight from unsprung to sprung is the way forward and meanwhile trying to ride a light rear rim and cassette is the next best thing. I remember some bike tester talking about the Stumpy in a downtime podcast I believe and the guy was saying they thought the alu version was sluggish with bad rear suspension because it was alu and for whichever reasons they put the rear wheel of the carbon stumpy and all the negative traits of the alu version were gone and the bike was feeling similar to the carbon. That tells us two thing, first carbon frame are way overrated, second, try to keep unsprung mass as low as you can.
  • 2 0
 @Balgaroth: so, use the heaviest frame material possible, drink lots of beer, and do not defecate pre-ride. It's only ratio-nal
  • 3 0
 @ceecee: not quite, body weigth is not sprung mass as it moves independently. And as it does to control the bike it requires energy whereas high spring mass does is inherently. But yes heavy front triangle, light swing arm, light wheels, gearbox and USD forks would be the ideal scenario
  • 1 0
 @Balgaroth: I won't poop
  • 1 0
 @Balgaroth: it should also tell you to not put too much stock in any editor’s reviews that you don’t personally know. The lack of understanding that leads to missing this pretty obvious point of comparison between bikes is far more common than you might think in the cycling press
  • 16 0
 Those flex stays are definitely optimistic..
  • 13 0
 I don't think that anti-rise is ever affected by what gear you're in, perhaps you meant anti-squat?
  • 14 0
 Yes, indeed. Anti-squat is not affected by gear choice with a gearbox.
  • 10 1
 Was thinking same. Second article about this bike that did that. I blame ChatGPT. Smile
  • 6 0
 Don't you love it when you know more than the marketing dweebs. You nailed it boss.
  • 1 0
 @SpeedgoatDesigns: I blame copy and pasting a PR typo.
  • 12 0
 The Viral looks needs a bit of getting used to, but then I think it's quite the jaw dropper.
  • 2 0
 I'm surprised it's still 35 lbs. It looks like it should weigh less, but then I guess all the weight is in the gearbox. At least it's in a good place - low and centered.
  • 11 1
 Well, I've certainly been infected, that Viral has contagious looks.
  • 6 2
 That's not funny I died from covid
  • 5 0
 I may be biased by living in Austin and knowing the Chumba guys, but that Sendero is pretty sexy. Throw a suspension fork on there and that is a hard bike to beat for the South Austin trails.
  • 4 0
 Lots of neat stuff going on with that Viral. The seat clamp is so tidy. And check out the rear dropouts - looks like a little titanium leaf spring to avoid using a bearing/pivot and have a flex stay.
  • 2 0
 The EBM process confuses me. Aluminum melts at 700degC, titanium goes much higher. Is it actually sintering they're doing there or am I missing something? I get the annealing bit but the fusing part is what I don't quite get yet.
  • 1 0
 Yes, there is still a laser sintering process happening. This process is an evolution of DMLS and still uses powder to sinter each layer with the laser.
  • 3 0
 @ViralBikes: Ah thanks for clearing that up. I knew SLS and then someone pointed me at the fact that SLM is more common for bicycles now where they actually melt the material. So I was expecting that for EBM considering it is called like that, but apparently this isn't melting but back to sintering again. This really is confusing for the casual Pinkbike commenter!
  • 2 0
 You can't really anneal something while you're working it, right? The whole point is to bring the entire mass of the material to it's annealing temp so it all becomes cohesive/ plays nice. Can someone explain to me how they're able to anneal without... Annealing?
  • 3 0
 Since the build volume is kept at the annealing temp, each subsequent layer is annealed to the entire part and continues annealing with the addition of the next layer. It's kept at that temp for the entire build, and thus 'continues' to anneal during the build.
  • 1 0
 @ViralBikes: that's so cool! Thanks for letting me know! Do you the annealer hot for a certain amount of time after the piece is finished? Glassblowers use the annealer to bring to temp and cool slowly, do you have to do that with ti? Thanks again for responding
  • 2 0
 @therealnobody: It takes about four hours to cool down. The chamber itself is under a controlled atmosphere (in Helium at around 0.4 bar).
  • 1 0
 @ViralBikes: that's so cool! Thank you for letting me know!
  • 5 1
 This Niner guy is another version of Ellsworth. Too much tooting of own horn.
  • 3 0
 Viral looks cool, just wonder how durable the belt tensioner is, it's location appears as if it will have to endure rock and log lashings quite often.
  • 6 0
 Agreed. This bit is a bit exposed although there is a solid bar of alloy paralleling the spring that would hit first in case of a strike, but we're looking at designing our own pulley wheel that will not be as exposed as this one is under the belt ring.
  • 4 0
 @ViralBikes: Any plans to make an eeeb with the Pinion MGU?
  • 2 0
 That belt tensioner looks unnecessarily complicated. It seems a relatively simple task to design something much simpler that would do the job equally well.
  • 4 0
 It looks to me like a Pinion tensioner, not one Viral cooked up. And yeah... no way that's lasting long on any bike I'm riding. My Zerode has an in-house tensioner that's considerably less exposed.
  • 1 1
 @ViralBikes: Absolutely SICK bike Viral!
  • 5 0
 Chumba? Did they buy the name?
  • 1 0
 Right? Artical says chumba builds in steel and titanium and I was like "since when"? Cause all the chumbas I remember were aluminum...
  • 2 0
 "without needing a breakaway point in the seat stay or chain stay."

There is a breakaway point in the chainstay. It's that bolt-on bridge you just mentioned.
  • 1 0
 Protip: If your bikepacking anywhere remote, Shimano 11sp is the ticket. Not only is the chain faster and quieter then sram flat top, you might be able to find one if you have an issue.
  • 1 1
 That Viral is awesome! Definitely interested in that bike to replace my Zerode Taniwha in a couple years, more space for water bottles and frame storage to use as a bikepacker.
  • 3 0
 long time no see......CHUMBA Bike
  • 2 0
 top one looks like it was designed by chatgpt when asked what a retromodern mtb would look like.
  • 1 0
 I'm really digging the looks of that Viral, it looks like there could even be room for two water bottles on the downtube!
  • 1 0
 how do you change the rebound on that superdeluxe with the Viral? I see the Niner influence btw. Not for me
  • 2 0
 Taking off the lower downtube cover exposes the shock and rebound adjustment. No tools required for removing the cover.
  • 2 0
 @ViralBikes: ah I see that now, cool
  • 2 0
 Why wouldn't there be pedal kickback from the gearbox?
  • 4 0
 While pedaling, it would still add the same amount of resistance to the pedals during suspension movement, but while coasting, there is a second 'freehub' in the gearbox as well, which allows the belt to rotate backwards without affecting the crank position.
  • 2 3
 That doesn't make sense. How would belt rotating backward be different than pedaling? If the belt could rotate backwards freely then you wouldn't be able to pedal.
  • 3 0
 @sadzo263: when the freehub is engaged the belt will rotate with your pedal stroke, when it's not engaged, ie, coasting, it allows rotation of the belt backward.
  • 1 0
 The anti rise is constant in a gearbox because the suspension can be designed around a single cog vs trying to manage changing levels of “pedal kickback” that results from having a range of gears at the rear wheel.
  • 1 0
 @ViralBikes: Is this second "freehub" electronically engaged/disengaged? Been thinking that throwing that in a freehub is the best use for electronics that hasn't been done yet, better than in derailleurs IMO. Surprised it hasn't been marketed more clearly if that is the case.
  • 2 0
 @ripcraft: no, it's a mechanical interface, but could be cool if controlled electronically.
  • 2 2
 @ViralBikes: if it is like a normal freehub in the back wheel, then it would depend where in the "play" would you be in the moment of the impact on the suspension. It could be more or less amount until the "freehub" engages and if it would already be close to engaging, the pedal kickback could still occur...?
  • 1 0
 @sadzo263: the system works similarly to the rear freehub, which allows rotation backwards but not rotation forward. This also exists in the gearbox itself. It allows rotation of the belt backwards but engages when rotating forwards. In this regard, the belt is free to move backwards, but not forwards.
  • 2 0
 @ViralBikes: I think you might have it backwards.
  • 1 2
 @ViralBikes: Look. The front chainring with belt rotating backward is exactly the same as chainring being stationary and cranks rotating forward, just different component is stationar, but the direction is the same. How would belt rotating backward be different than pushing on the pedals (crank rotating forward)....cranks would just spin and spin freely and you couldn't pedal.
  • 2 0
 @MorganBH:
On a gearbox, when you pedal backwards, the cog in the front stays in place, i.e the Belt can move backwards, meaning no pedal kickback Smile
  • 1 0
 @edfw: Do you pedal backwards when going downhill?
  • 2 0
 @edfw: pedaling backwards with crank stationary is the same as cranks being stationary and chainring moving forward not backward. Unless you would pedal backward, the front chainring simply can not move backward. Its simple, if the chainring could move backwards, you couldn't pedal at all
  • 1 0
 @sadzo263: everyone who uses mechanical devices should have a basic understanding as being of physics and how a bike suspension works.

Pedal kickback is caused by the suspension being active, which happens when pedaling and coasting.

Just think about it this way: what makes the chain in a bike shorten when the suspension is compressed?

The suspension (unless it’s concentric) is moving the wheel away from the bottom bracket as it compresses, so the distance between the wheel and the bottom bracket increases which “shortens” and pulls on the chain.

That chain shortening is the kickback you feel at the pedals.
  • 2 0
 @edfw: There is about 12 degrees of play in the pinion freewheel, but after the pawls engage, the belt moving backwards would pull on the cog and rotate the cranks. The belt can rotate forwards without moving the cranks. I have four pinion bikes, and I think the pedal kickback on them is very low, but not necessarily zero.
  • 2 0
 I read this as the Optometrist.
  • 1 1
 I sure do hope one in particular of those companies have model called "Wamba" in their lineup.
I'll leave you guys guessing which one I refer to.
  • 1 0
 They used to make the wumba. It was their dh bike. My favorite model name they had was 'chupacabra.' This company has quite a history.
  • 1 0
 @mrgonzo: I remember that. Is it the same company? Thought they went belly up long ago.
  • 2 0
 The standover doesn’t look great on that Viral
  • 1 0
 Yea I was wondering why it looks so high. Amazing looking bike though
  • 1 0
 @mechatronicjf: likely for bottles and frame storage. Standover only matters when your feet are off the pedals … I usually ride my bike, not much into straddling it Wink
  • 1 0
 Most of my bikes have decent paint/surface damage in pretty much the exact location of those really thin flexy bits...
  • 1 0
 Should be named the Sender Zero. Can't imagine sending it off a cliff, without Bendero.
  • 1 0
 More close ups required of the rear brake mount on the full sus... The bolt head looks like it sits UNDER the calliper!
  • 1 0
 That Viral looks seriously flimsy and I would be seriously surprised if it isn't as flexy and fragile as it looks.
  • 1 0
 The rizzo´s bike was looking best than this.... But it´s good see the Enve´s moves. I really like it.
  • 1 0
 I mean......I wouldn't kick them out of bed!
  • 1 0
 The Chumba is absolutly beautyfull !
  • 1 0
 Nice bike but what happened to the OG Chumba?
  • 1 0
 i love when suspension kinematics moves back to the late 90's
  • 1 0
 @alvin-outside: you mean "tenets", not "tenants".
  • 1 0
 Innovation is a double-sided sword!
  • 1 0
 printed ti bikes are sooooo uggly.
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