Bike Check: Acoustic Cycles' Steel High Pivot is a Thing of Beauty

Nov 17, 2022
by Dario D  


In the flurry of beautiful and interesting bikes that popped up at the Philly Bike Expo, we caught sight of this steel high pivot machine and had to know more. At his workshop in the small town of Pine, Colorado, Zach Geller cooked up this 160mm 29er to be his personal trail bike. The build is certainly eye-catching, and the undertaking is no small feat, so I sat down with Zach to get the story on the development of this bike, and on Acoustic Cycles in general.



How long have you been building?


I started building in 2019, and have transitioned to building full time as of this year. Taking a weeklong framebuilding course with Brew Bikes in Boone, NC kickstarted the new venture.

Why custom over stock, especially in the high-performance mountain bike space?


I had always worked in bike shops, and was consistently on the yearly cycle of buying and flipping the newest bikes on the market, but over time just got sick of keeping up with the updates. I wanted to make something that would fit me and my uses, while also lasting a long time. I've been riding one of my first hardtail frames for four years now, and it still works just as well as day one. The beauty of a custom frame is the small geo tweaks you can make, as opposed to being locked into stock sizing.


As someone always iterating on geometry and design, does it feel like mtb geo has reached a point of balance?


I’d like to say we’ve hit a plateau, but someone always comes out with something you want to try. Within the past couple years, we’ve come to numbers that work pretty well for descending and climbing. Reach is a strong preference for people, so that’s why I stuck with front end being customizable.

The numbers are pretty bang-on for a modern enduro bike.

Why go high pivot for your first full suspension? How did the design and build process go?


It might sound cliche, but I ride up for the downs, so I wanted to make the best descending trail bike I could. I've always ridden 4-bar bikes, and preferred that to the single pivot alternative, so it was worth the extra complication for me.

I design in Fusion360, BikeCAD, and Linkage, and was able to get a pretty firm idea of how the suspension would perform based on that data. I actually pulled a lot of info from the Pinkbike Behind the Numbers articles, which helped me optimize relative to other bikes out there.

Idler placement was a tricky one to determine, so I built a test jig that allows me to slightly change the location and size (currently 17t) of the idler to optimize things. It's been snowing since I returned from the Philly Bike Expo, so I haven't had a real chance to ride the bike yet.

One last note on the build process - I ended up 3D printing a plastic model of the entire rear end of the bike, in order to test fitment and clearances before I pulled the trigger on a metal assembly. This was a huge help in dialing in the design without having to iterate too much.

High performance purple.

How would you describe your flavor of frame building?


From a 10,000’ view, the majority of builders are road-oriented, where Acoustic is very focused on mountain bikes. I care a lot about form and function working together, so that every bend is intentional and the lines flow well. In the end the bikes have to ride well too, I want these things to last.



Nice touches.

Do you have any primary influences when it comes to bike design and fabrication?


Community-wide, there's just so much information and help. Chris at 44bikes is on his fourth iteration of his full suspension design, so he's been a great resource. Adam Prosise machined the rockers for the bike and was a good sounding board for the manufacturing and suspension performance. Sean Handerhan made the dropouts, clevis, and main pivot. The clevis required 5th axis machine, so he was key to getting this thing made. Walt Wehner of Waltworks has a trove of information on his blog, which always proves helpful.

It takes a village.

Do you think there are lessons larger manufacturers could learn from solo fabricators like yourself?


Smaller builders can pivot much quicker and try things sooner. Prototyping is quick and immediate, which is great for testing out ideas and fit. We're seeing more desire for geometry tweaks and customization in mountain bikes, but ultimately it can't match what you can get with a custom builder.

The supply chain is much more immediate, which is just nice from an availability standpoint.


Are there any bikes out there you’d love to ride? New or old, what intrigues you?


Evan Turpen's Contra bike, and the Forbidden Druid. I want to talk to Evan about his design process, and what all changed between prototype and final product. The Forbidden design seems to take a different approach to the high pivot design, and I really like how transparent they are with information on their website.

Are there plans to scale this design, maybe even offer a stock frame?


My current pipe dream is to have a stock of rear end assemblies ready to go, and be able to weld up custom front triangles for each customer. I'm currently in talks with a metal 3D printing shop about getting pivots and dropouts made, in order to shave weight and to help make fabrication easier and quicker.



Not that it matters, but how much does it weigh?


Current build weight is about 40 pounds, maybe closer to 41 now as I just installed a coil conversion on the fork.


Contact Zach and see more at the Acoustic Cycles website.



All photos by Alexandra Demopoulos.


121 Comments

  • 191 6
 now this, this is hot
  • 13 0
 Shoutout to Ollie in the Springs. Super good guy and real good at painting bikes
  • 10 0
 You’d think we all would’ve heard of Acoustic Cycles before now!
  • 7 23
flag PHX77 (Nov 17, 2022 at 14:38) (Below Threshold)
 I’m surprised there aren’t more pants being crapped in in the comment section because it’s called acoustic cycles. What’s next? And eBike company called Moped cycles?? Also f*ck headset routing and auto play.
  • 11 0
 @PHX77: If it's Acoustic to differentiate from Ebike, then I'm triggered. I'll give him the benefit of doubt and assume it's acoustic as in small batch, artisanal craftsmanship.
  • 19 1
 those cranks should be censored, they are too erotic for the children on here
  • 8 0
 @ryanandrewrogers: Actually, the cranks are NSFW (Not Safe For Wallet) for all of us adults who had “3D Violet” everything in the 90’s.
  • 3 2
 @WRCDH: WHAT DID YOU SAY??!!!!
  • 2 1
 @danstonQ: If you have to ask...
  • 1 0
 @phx77 @plyawn: clearly needs to differentiate from ebikes with the same weight lol.

super cool machine tho
  • 109 3
 Someone needs to tell Zach that he could save about 60 grams if he routed the cables through the headset.
  • 13 4
 Yay, my bike is 39.999999 lbs!
  • 46 7
 Much rather have one of these than a Yeti
  • 37 3
 And there’s a good chance it’s more affordable than a Yeti as well, in spite of being custom-built in CO
  • 21 2
 Dang, he must of had someone else tune that Push. They usually get their panties wadded at an 11.6 being on something they don’t offer…

Anyways, sweet bike!! Clean lines. Rad story behind it. Looks like it’ll ride well too!
  • 17 6
 To be fair, if someone were to put an 11.6 on a bike that the tune wasn't designed for and it felt like crap, they'd say the shock sucks. I get where Push is coming from.
  • 16 3
 @Tmackstab: having spoken to darren a fair bit in the past ,he likes to do this so basically your not getting a bag of shit performance out of something the guy pours his soul into making
  • 3 0
 @Tmackstab: If he's designed the kinematics himself and can reference to a bike that is supported it might be pretty bang on. I had an older 11-6 that was tuned by a Push centre for an unsupported bike, so it does happen.
  • 4 0
 They wouldn't offer it at all for my bike. Meanwhile, the Ohlins has been holding on just fine for years now.
  • 2 0
 The dude designed in the bike using industry standard software. I'm sure he could pass on whatever information Push needed to tune the shock.
  • 1 0
 @heinous: yeah the bike is a mid HP, FSR style, quite a few bikes on the market like that now with fairly similar travel and stroke so kinematics wise I am pretty optimistic on the fact you could easily find a mass produced doppelganger.
  • 21 0
 Title says it all - a thing of beauty indeed. I'm a sucker for any full sus where the top tube and seat-stays line up
  • 7 0
 agreed like the Spur and Shadowcat
  • 8 0
 Also like when the downtube doesn't have a big bend as it nears the BB.
  • 15 0
 Looks amazing and should work very well,but 40lbs?
Sorry if I don't buy the "weight doesn't matter" movement,I don't imagine myself riding a bike heavier than a DH race bike up and down the mountain.
  • 1 0
 Weight definitely matters to an extent, but once you're sat on it, it's not as big a deal as you'd think, particularly if the suspension/geo is setup correctly for efficient pedalling. If the weight is mostly sprung (which it is with you on it) it makes very little real world difference in my experience. It's more noticeable when lifting it onto the car!
That said, 40lb is pretty ridiculous. My enduro bike is 35lb and that's plenty.
  • 1 3
 @redrook: And not that the weight is inconsequential, but steel frames provide such great pedaling efficiency, that it really does feel like it negates a ton of the weight when climbing.
  • 4 0
 @mtb2112: "but steel frames provide such great pedaling efficiency" how dat?
  • 1 0
 @mtb2112: I'm not sure a steel frame provides any additional pedalling efficiency.
  • 1 0
 @redrook: You're right. Lateral stiffness doesn't provide any additional efficiency when pedaling.
  • 1 1
 @mtb2112: Why would it? How would that help pedalling efficiency? And you're hardly putting much lateral force into it unless you have a completely weird pedalling technique. It's not making any perceptible difference to pedalling efficiency unless you can prove otherwise. Show me the numbers.
  • 14 1
 I would so much rather have this than one of those silly Yetis
  • 3 0
 It also just seems like way more of a flex, and a frame is probably not too far off in price.
  • 13 1
 Pittsburgh, not Pittsburg.
  • 7 0
 Such a rad-looking bike Zach! Nice work. If you ever find yourself on Vancouver Island, stop by for a beer and a ride. We can talk high pivots till the cows come home... Happy trails!
  • 4 0
 Wow beautiful bike from stem to rear axle . The lines just look right and bad ass . Love the rearend suspension, the lower arm pivot placement looks just perfect for the upper stay to pivot . You can visualize the the axle path easily through compression. Gorgeous George!
  • 8 2
 Hooolllly SH*T! So stoked to see this pop up, Zach! The details are drool worthy
  • 5 0
 Started building in 2019?! That was like last week... would have guessed this was built by a seasoned frame builder of a atleast a decade. Well done...
  • 8 5
 "Not that it matters, but how much does it weigh?"

*grabs pitchfork*

After him, Comments section!

I don't have enough energy left for my gnarly blue descents unless my bike weighs 28lbs.
  • 2 0
 160mm travel from a 57.5mm stroke with a 29er rear wheel. A full 65mm stroke conversion would get 175-180ish mm travel from the frame if there’s enough travel built-in in the design, possibly with a 27.5 rear wheel for mullet conversion.
  • 7 1
 Heavy Metal Kavenz
  • 6 2
 That is one pretty-looking bicycle right there.
  • 4 0
 Is there gonna version with a preamp?
  • 1 0
 i did wonder if it wasnt an ebike
  • 1 0
 @danielfloyd: Was about to ask the same thing!
  • 3 0
 Purple ano is an old school staple. its garishly fitting on a mountainbike. Turns heads wherever you go
  • 1 0
 Anyone out there using Docol R8 for their frames?
Heard great things on the metal but I know it’s pricey and was curious what others thoughts are on it and also how it would ride
  • 3 0
 Unless you can get it butted, it would be like a plain gauge 4130 frame.
  • 2 0
 roll cage tube innit ??we use the SSAB a stuff in sheet and plate form ( think ballistics) i have a PDF somewhere from SSAB touting it for motorsports, dunno what advantages it would give over reynolds straight gauge motorsport stuff which i believe is 631 and from there if its expensive just use reynolds or columbus butted
  • 1 0
 I'd like to try R8 or R10, but, so far the thinnest gauge I've found it in is 2mm - though, I haven't checked for a few months. With it's (listed) properties I'd like to go from, say, the 44.45 x 1.2mm Downtube I currently use, to a .9 gauge. I build for strength, but would love to cut a few grams off my DH frames.
  • 2 0
 My wife graduated from LSU so the first thing I thought of when I saw the thumbnail was “Geaux Tigers!”

The second was “how did he tune that ELEVENSIX?”
  • 2 0
 I got to see this bike up front in person at the Philly Bike Expo and it looks AMAZING!!! I also got to speak with Zach who is so grounded and artistic, and a super nice guy.
  • 3 0
 Engineering driven design, but with purple parts. That's about as good as it gets!!
  • 2 1
 Man what a beautiful bike! That colour combo is spot on. They should out some AXS stuff on it just to be ironic ;-). Kidding.
  • 5 3
 That’s a sweet looking bike, and I’m not a fan of the term “ Acoustic Bike”, I much prefer “Real Bike”.
  • 3 0
 OMG. Sexiest bike I've seen all year, and I own a damn sexy bike.
  • 3 0
 Steel frame, coil front and back. My kind of a bike!
  • 3 0
 Head badge is an absolute work of art
  • 3 1
 This is what a bike should look like, not those monstrosities like the SC bronson with a 10" diameter downtube
  • 3 0
 purple is the new purple is the new purple
  • 2 0
 Wow maybe the nicest looking bike all year, mucho props. Steve at Brew taught you well, very nice.
  • 3 1
 Those rockers look like they come off a Wallmart bike though. And I don't mean the color.
  • 1 0
 I must be looking at something different to everyone else. I have eyes, and on that basis I couldn’t ride that bike, it’s gopping!
  • 3 0
 40lbs with EXO tires. Yikes.
  • 4 3
 I can relate to every word here. And yes, that thing is beautiful, fantastic work, Zach Cool
  • 4 2
 Very nice. It looks like a steel Hope HB.916
  • 3 1
 jeezus, that is a well designed bike.
  • 1 0
 This is so freaking beautiful. And great job Sean, great to see Pittsburgh on here!
  • 2 0
 Represent!
  • 3 1
 Crank arms are stunning! What a looker!
  • 1 0
 Hehe. Beauty is in the eye of the beer holder and all that, the cranks are the only thing I'd change.
  • 5 3
 f*ck the bullshit $15k bikes PB keeps reviewing. THIS f*cking rules
  • 2 0
 Reminds me Accoustic Alchemy.
  • 2 0
 Hell yeah brother! Such nice work.
  • 1 0
 Reminds me of if the guys at Brooklyn machine works were still making bikes, very nice!
  • 1 0
 LOL my blog hasn't been updated since 2015, where did he even dig that up?

-Walt
  • 1 0
 You didn't ask him if the brand name was ironic?

Bad ass bike though!
  • 2 0
 I don't see any electricity, works for me!
  • 4 0
 @jesse-effing-edwards: That's what I meant, acoustic is like a derogatory term from e-bikers to describe normal bikes. They're just bikes.
  • 1 0
 @FredrikWestman: I know. I love that phrase, haha. Totally irritates some.
  • 4 3
 Not gonna lie, that is sick looking.
  • 4 2
 Love that badge
  • 1 0
 looks great just need a spicier looking fork and dropper to match ;-)
  • 1 0
 The pedaling mans kinda bike!
  • 1 0
 Make it in stealth black then I'm IN
  • 1 0
 Bonus points for cables on the outside bumps it up to an 11 out of 10.
  • 1 0
 Don't like internal routing anywhere but what a beautiful bike.
  • 1 0
 Such beautiful craftsmanship!
  • 1 0
 looks like a ripper, fast looking ride
  • 1 0
 Dope job all around. I want.
  • 1 0
 i tell you, it doesnt get much better than this
  • 1 0
 Beauty, with a name like that it better not sound like shit.
  • 1 0
 Pure AND techy, I'm in love.
  • 1 0
 It looks stunning, but 40lb!? That's almost e-bike weight territory!
  • 2 1
 amazing. I'd buy one
  • 1 0
 Sweet, looks rad .
  • 1 1
 thats brilliant. the a-arm layout looks like a formula 1 car geo-wise
  • 1 0
 Sweeeeeeettt!
  • 1 0
 I'd steel this!
  • 1 0
 Kavenz comes to mind
  • 1 0
 so cool bike
  • 1 0
 I guess it is HAPTIC too
  • 1 0
 short waist for the rear
  • 1 0
 LA Lakers!
  • 1 0
 Nice.
  • 3 4
 Needs 43mm more travel and a dual crown fork
  • 1 2
 As clichè as a #Ebike on a turbo trainer
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