Late last summer, I walked into my local bike shop in Duluth, Minnesota. The store mirrors most boutique outfits across the country; water bottles, lights, socks, tires, tubes and locks are clustered up front, leaving space for dense rows of road, cross and mountain bikes to fill the floor. There’s a well-worn rental desk and in the back, a small repair shop. But something was conspicuously missing — there wasn’t a single e-bike in sight.
When I asked the clerk if they had any in stock, he pointed to a far corner of the space. With that small bit of guidance, I found them easy to spot — large batteries, wider frames and lots of cables gave them away. Curious how an electric mountain bike compared to a traditional one, I lifted one off the rack. It was heavy, and I couldn’t help but think that the first thing anyone might take note of during a first encounter is the weight.
Then again, committed riders would probably make the same observation. People who are into bikes are, almost by default, obsessed with weight. I had a hunch that somewhere, one of them was losing sleep over it. And then I met Joe Buckley, head of Electric Mountain Bike Development at Specialized, who told me how his team approached the design of the Levo, Specialized’s flagship e-mountain bike.
“We rode almost every competitor bike,” he recalls. “None of them handled like a traditional mountain bike. They didn’t descend at the speed we wanted. They had to brake sooner. They’re all cumbersome — and it came down to weight. All of these bikes were way too heavy.”
The same cannot be said of the new Levo SL, which Specialized released on February 2, 2020 — and is easily the lightest e-mountain bike ever made.
Building a Lighter Bike
But reducing weight isn’t an easy problem to solve, even for a company with vast research and development at its disposal. The original Levo is 45 pounds fully loaded.
“We’re not pros, but we all love to ride. The entire office empties for a couple hours at lunch to get a lap in. In a lot of ways, we designed this bike for ourselves.”
“We still saw room for improvement,” says Buckley. “The fun part of riding is going fast downhill, and controlling that much weight is hard for anyone, especially smaller riders.”
Then he makes an unexpected admission: “The first Levo was overkill.”
Soon after Specialized launched the Levo in early 2016, it kicked off another project called SL. The goal: to make the Levo smaller, lighter and more like a traditional mountain bike.
“We didn’t know exactly how small it would be,” says Buckley. “It needed to be fun for smaller and less skilled riders. Most people don’t need all the power in the Levo anyway. Most use just a fraction of the output.”
At the same time, Specialized knew that the public perception of e-bikes varies widely, despite significant growing interest in juiced-up riding. So it strived to build a motor and a battery into the same form factor as traditional bikes.
For many in the office, this amounts to a dream bike. Jan Talavasek, director of Turbo Bikes, describes the early excitement: “We’re not pros, but we all love to ride. The entire office empties for a couple hours at lunch to get a lap in. In a lot of ways, we designed this bike for ourselves. We weren’t sure it was possible, but we were excited to take on the challenge.”
The SL dream bike began, as many breakthrough products likely do, as a boring spec sheet. Buckley kept it simple — essentially, stuff a couple hundred watts of power inside a mountain bike, without adding weight. It needed to be both nimble and fun, as well as quiet and smooth.
“No one likes a chainsaw between their legs,” says Talavasek, only half-joking. “We wanted SL riders to listen to the birds and enjoy the environment they are in.”
The spec sheet served as a map, describing the type of rider the SL would serve and setting targets for weight, stiffness and how it would ride. In the hands of the engineering teams, these smaller goals served as a route to the big one — making the bike lighter.
Next step: computer modeling. For six months, designers and engineers worked together to figure out what the bike would look like. Early iterations blended components from the Levo with those of the non-electric Stumpjumper and Enduro. But bikes evolve quickly, and the team couldn’t just copy and paste. The SL had to be new.
“It’s essentially high-stakes arts and crafts,” says Nadia Carroll, one of Specialized’s composite development engineers. “In a single frame, we’ll use up to six different grades of carbon, dozens of different placements and hundreds of different plies. Plies vary in size and shape, too.”
Carroll and her team spend a lot of time thinking about angles. “The strength and stiffness of carbon is all directional,” explains Will Chan, composite engineering manager. “If done correctly it will be ten times stronger per weight than any metal. Essentially this is super-advanced papier-mâché.”
If only it were as simple as soaking strips of newspaper in a flour-water mixture. “Layup design took us a full year,” says Chan. “During this process, we’re building and breaking things every day. It’s the most fun part, testing models in the lab and out with riders on the trails.”
Again, Specialized needed to hit the sweet spot between strength and weight: “We’re using composites to do everything they are supposed to do — and we’re trying to find their limit.”
Carbon Fiber and Motor Modules
The Levo SL is undeniably complex. The front triangle alone has 597 carbon plies — that’s a lot — and another 271 in the chainstay. “The number of layup permutations is almost infinite,” says Chan. By the end of the process, the team had tested more than 100 different designs, leveraging an in-house testing lab, which he describes as “Specialized’s secret sauce.”
Most of these tests are proprietary and hidden from outsiders. One of the most unique is a CT scan, the very same found in hospitals. “It can show things that previously weren’t possible and helps ensure robust designs,” Carroll explains. “Each scan produces 3,000 photos, helping us isolate weak spots.”
It’s also the main factor in making the Levo SL the most substantial investment Specialized has ever put into a single bike.
With frame designs taking shape, the process flips to the motor specialists in Switzerland, run by Talavasek. This team, just 30 engineers and developers, leads all things electric at Specialized. They build “the module,” which includes batteries, remotes, the gearbox and the motor, plus the software that manages all of it.
That module is also the most significant difference between the SL and its predecessor Levo. It’s a fully custom unit, the first of its kind in the entire industry. It’s also the main factor in making the Levo SL the most substantial investment Specialized has ever put into a single bike.
Talavasek’s first step in creating this system is outlining the right power specifications. The initial aim was 150 watts and 1500 grams, but this evolved to 250 watts and 1900 grams. “A couple of months in, we realized our goals weren’t perfect, so we adapted them. More power added weight, but it felt necessary.” This process included many more rigorous tests, which were challenging to pass while keeping the bike lightweight.
“Even picking the right motor housing wasn’t easy,” says Talavasek. “I’m not sure how many motor iterations we went through, but I can tell you it was a lot. Dozens, if not hundreds. We quickly learned that a lot can go wrong when field testing that you won’t see in a lab. We tested this bike more than any other.”
Motor development was scheduled to take two years; it took the team nearly three. The chief issue was creating a natural ride feel inside a motorized experience.
“In technical situations like climbing tight switchbacks or going over rocks, a natural feel is very important,” explains Talavasek. “We took the time to optimize the software to behave the right way.”
The Final Ten Percent
With both the frame and motor design nearly complete, the SL project migrated to yet another continent and reached Specialized’s factory in Taiwan.
“Mass production always adds a slew of challenges and small changes to the design,” says Buckley. “Scaling up manufacturing — the right tooling, optimization, and assembly lines — is a huge job.”
Buckley and his team don’t start talking to the factory until the bike is roughly 90 percent final. “That’s deliberate. We want to start the conversation before the design is locked, to make sure the bike we’ve dreamed up is possible to manufacture.”
Such a thing isn’t guaranteed, and this crucial stage could keep a dream bike as just that. “The finalizing process usually takes about a month. With design locked, the factory starts to create tooling for mass production.”
The rest of the process for Specialized is relatively standard, starting with pre-production runs off the factory line and testing these early prototypes for quality and safety. “We do this over and over for all sizes of bikes. It takes a lot of time.” Even after making the final 10 percent, Buckley says getting to full production took over a year to get right.
The result of such a long and painstaking process? The final product is a 35-pound electric mountain bike that, on a single charge, provides a boost for two hours and 1,000 meters of climbing under full power. In eco mode, you can ride three times as long.
“Out of the box, the SL is nearly ten pounds lighter, making it the perfect bike for a full afternoon ride,” says Todd Cannatelli, Specialized’s business manager of mountain bikes and equipment. “It gives you a pure feel and enables you to go more places. With the added range extender, the SL can take you nearly the same distance as the Levo, and the travel is almost identical. The difference all comes down to feel.”
Specialized’s ambitious goal is for the SL to pull core trail enthusiasts into the e-bike world. “With the motor and battery turned off, there is almost no drag on the system — no other e-bike feels this real,” says Cannatelli.
What he means, I think, is that no other e-bike feels as much like a regular bike. And that might be the key factor that allows Specialized, or any other bike maker for that matter, to convert core riders into e-believers.