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In Deep: Evan Turpen, Contra Bikes, and the Next Step in High Pivots

The biggest surprise at this year's Sea Otter showed up late and stole the show.

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In the weeks leading up to the re-re-re-scheduled Sea Otter Classic, there were whispers that it would again be postponed. Brands like SRAM and Santa Cruz had not booked booths, and there was a reshuffling of expo plots to keep things from feeling too empty. It seemed like just one more sudden high-profile no-show might be the last straw. And honestly, I have a few industry colleagues whose fingers were crossed for exactly that to happen. Like fourth-graders watching a blizzard coat the streets, we were hoping we’d wake up to the news that school is cancelled. 

But the show went on. And the moment I started bumping into people I hadn’t seen in a year (or in the case of Sea Otter 2021, two-and-a-half years), I was glad it did. After the past year-and-a-half taught us that we could technically survive without races, press camps, or even in-person meetings, Sea Otter was a reminder of everything we’d been missing. Cool, unpredictable things happen with more frequency and with more impact when you put thousands of cyclists together. And by far the coolest and most unpredictable thing that happened to me was seeing bike designer and former racer Evan Turpen the moment he stepped into the expo grounds, early on Sea Otter’s last day, carrying the first production-ready model from Contra Bikes.

It was the brightest black bike I’d ever seen. Not only because it was completely spotless, but the high contrast between the powdercoated steel mainframe and machined aluminum hardware almost made me squint. It was inescapably exotic, and the more you looked, the more exotic it became. There was the slim steel frame tubing, the aggressive posture, the labyrinthian (but actually quite simple) linkage. And of course, there was the high pivot, uniquely far forward on the frame, highlighted by the huge, shiny idler pulley. A crowd immediately gathered, and it seemed Turpen would have a long day ahead of him.

“I ended up going around and talking with a bunch of different vendors. It’ll be a long time until I’ll be selling complete bikes, but I’ve got to make sure that I can at least get shocks and bearings,” Turpen told me when we caught up again after the show. It turned out that particular Sunday marked the end of one hell of a crunch. “There was a lot of stuff going on behind the scenes to get it down there. I finished assembling the frame at probably 2:00 in the morning on Saturday, and then got two-and-a-half hours of sleep, then started building the bike.”

Turpen made some waves in the summer of 2020 with a similar-looking high-pivot steel frame, but the bike he showed up to Sea Otter with is built around a fundamentally different design. He went back to the drawing board soon after that early prototype, and his new vision was more than ready for the real world. While the prototype was a linkage-driven single-pivot, the best way to think about what’s going on here is to picture a high-pivot version of a lower-link VPP from Santa Cruz, but with a vertical shock orientation instead of horizontal. And to clear up something that’s confusing even on close inspection, the vertical machined aluminum beam doesn’t make this a six-bar system like Yeti’s new e-bike or Felt’s old Virtual Link. It’s fixed on the top and bottom end to the pivot points, completing the rear triangle.

This design achieved what Turpen wanted to change about the original design. He just needed the funding. “My hands were kinda tied behind my back,” he says. “I had used up all of the personal loan that I got for myself originally to start this thing because I just kept going. Then finally, money came through and I was able to start to do stuff quickly. But it was literally six weeks before Sea Otter when I started getting quotes and handing over parts to be CNC-machined.”

For the several crucial aluminum parts, Turpen relied on the same local machinist who helped make the prototype into a reality, Dave Mather of Mather Machining. That even included the precise work of fabricating the wide-narrow idler pulley.  The frame itself was again welded by John Caletti, maker of jewelry-class steel and titanium hardtail, gravel and road bikes. But that was also pretty last-minute. “We finished welding Monday night before Sea Otter at about eight o’clock, and then I went to the powder coaters the next morning.”

The fit and finish on the model that Turpen showed up to Sea Otter with didn’t show the slightest hint of all that chaos. Looking at it, it’s clear the thought that went into every element of its design. These photos capture some of that, but Turpen really wanted there to be a physical debut. And Sea Otter was a poignant place to do it.

Photo: Satchel Cronk

“Going to Sea Otter for the first time was super eye-opening,” Turpen remembers. “That was 2001 or something. And what was really cool about it was the fact that you didn’t really have the internet. You maybe just had Mountain Bike Action magazine. That year, Intense had a prototype M-16, one of the first bikes I remember seeing at Sea Otter. There was so much buzz around new bikes and actually having to find them. That’s opposed to now, when it’s just like, ‘We launched this last week, and now you can come and see it.’” Turpen longed for a bit more excitement. Something that would make showing up at an event more worthwhile. “For example, BMC’s new line, SCOR. It would have been really cool if it had been released at Sea Otter. Because you’d see it and just think, ‘What the hell is that bike?’”

I got a chance to ask Turpen that exact question. Contra’s debut model is very different from the prototype that was revealed last year, and not necessarily in ways that Turpen expected. For one thing, it’s still made of steel, but he was planning on making the switch to aluminum for the production model. “I thought I could make it lighter and stiffer than steel but more affordable than if it were carbon. But the reality was that there’s very limited availability on bike-specific extrusion in aluminum.” The front triangle could have been made of easier-to-source round aluminum tubing, but the rear triangle needs special shaping that is specific to the bike industry, and it’s suffering the same supply shortages every other corner is. Turpen kept every option on the table, though.

“One thing I looked into was bonding aluminum. It’s like taking tubes and then having fancy machined lugs. Similar to what the Atherton bike is. But there’s a lot of issues because you have to very precisely machine every joint. And then, I’m not a chemical engineer, and there’s a lot of science that goes into bonding alloy.” He then explored fully machining the rear triangle, like Pole or Hope do, but steel simply made the most sense. So, the materials are the same, but again, the suspension design is totally different. And getting there didn’t happen in a straight line or in a single step for Turpen.

I think I made three different bikes that went through the full development process. An aspect of one of them would have infringed on DW-link. So I had to abandon that, even though the patent is expiring soon. And then another one that I developed was just not going to handle the forces that it was putting into the frame, even though it accomplished some really good kinematics. Then, just the layout wasn’t as aesthetically pleasing. It didn’t put the things where I wanted them. It would have been difficult to get a low toptube and a low seat tube. Ultimately, this bike that I ended up with is way better than anything else that I developed in the past.”

Turpen is mostly self-taught. Those prototypes were developed virtually, where he would work out not just pedaling, braking and descending characteristics, but also durability and longevity. He learned how to use FEA, or finite element analysis, so he had an idea of how strong the design would be before it went to prototyping and, eventually, real-world testing. “One goal was directing forces in the bike in a way that allowed me to make it lighter.” The rear triangle on the new version is 600 grams lighter than the prototype. Turpen sounds like a veteran framebuilder when talking about his FEA findings. “It’s hard to tell, but pivot forces on bikes can be tremendously high, and they can be going in totally the wrong direction. I think it’s easy for somebody in carbon to just throw a huge amount of material or do a specific lay-up and create a complex profile to compensate for that.” Turpen’s decision to work with steel meant he had to be more thoughtful. 

“I have the shock pushing upwards, perpendicular against the toptube which, by itself, would be a bad thing. But then you have the upper leg pulling down on the toptube, and the two almost counter each other to where there’s very little stress.” Turpen explains the forces are similarly low around his chosen lower-link configuration. On our hour-and-a-half phone call, I learned more than I’d ever known about frame stresses, and we hadn’t even mentioned how the bike was designed to ride.

One aspect that carried over from his prototype with minimal change was the axle path. Of course, high-pivot bikes are meant to have more rearward axle paths, but several mainstream brands who recently entered the scene seem to be hedging their bets a bit. Like, the new Devinci Spartan’s axle path is only rearward for the first portion of the stroke. Contra Bikes only start to go near-vertical at the very end of the stroke.

The Contra’s design also allowed Turpen unique control over anti-squat. The idler pulley is fixed to the front triangle with a separate CNC’d part, and he is free to position it wherever he wants to control where the force is coming from. In his prototype, which used a very different design for the idler pulley, Turpen was able to achieve 100-percent anti-squat in just about any gear, but opted to raise the anti-squat slightly for this version. “If you had a motor on the bike and you weren’t moving up and down, it wouldn’t be moving at all with 100-percent anti-squat. But then, when you add a person and their undulating legs and body, you need slightly more than 100 percent to start to make that feel efficient.” The pulley itself was just as important. It’s big, and it will likely go up to 24 teeth from the already large 22 teeth it is now. Turpen finds that smaller idler pulleys are noisier, less efficient and less durable. 

Turpen did make some more significant changes when it came to the leverage rate and curve. Though both this new model and the prototype feature an almost totally straight progressive curve, he built slightly less overall progressivity into this version. “I was running zero volume spacers and was never having a harsh bottom-out, even with adequate sag,” says Turpen. “I thought that might be a little much.”  The overall progression numbers weren’t off the charts, but he says that you need to think about leverage rates differently on high-pivot bikes. “It’s kind of hard to explain, but basically because the wheel is also moving back, you get two different leverage ratios. You have a vertical leverage ratio, and another leverage ratio, which is along the axle path. And that one actually starts out much softer off the top.” So, to keep the rider from hitting that progression too harshly, this new version is slightly more linear. 

Hearing Turpen talk about these things, you can tell he intimately understands how to get what he wants. There was little concern that the last-minute frame build might yield something unexpected. He had done his homework. “When you’re trying so hard to make a bike work a specific way with a specific linkage, it starts to become totally intuitive,” Turpen explains. “Where, if you move this pivot to that location, it’s going to change it in this way. Like, the very first time you build a bike wheel is probably pretty nerve-wracking and it doesn’t end up being very good. But over time, by learning what happens if you turn a nipple this way, or that, you see what happens. And learning from that, you basically program yourself to know what to do to accomplish your goal.”

So now, now that the industry buzz is a-buzzing, Turpen is facing the hard part. He is hoping to have production bikes by this coming spring. There’s no word on pricing, how many frames will be available, and of course, how quickly they’ll sell out. But timing for Contra Bikes to hit the scene seems pretty perfect. Now that the high-pivot bandwagon has reached full speed, we’re ready for someone to start rocking the boat.

Bike photos: Ryan Palmer