A bike with a built-in assist: Trek’s newest entry in pedal-assist cycling, Ars Technica

        

One of my favorite moments in bicycling comes when you find the exact right combination of effort, gearing, wind speed, road surface , and slope. For a few magic moments, acceleration feels effortless, and you rocket forward like there’s a giant hand pushing you from behind.

Last week, I experienced something similar, but it came while ridingUphillon the toughest section of Central Park’s loop road. The effortless acceleration was courtesy of a compact but powerful electric motor embedded in the frame of a new line of bikes introduced by Trek. The test ride was meant to introduce me to Trek’s new models, but it also introduced me to pedal-assist bikes more generally.

The experience was very different from my expectations, in part because there are multiple experiences, depending on exactly how you tweak a combination of settings, gearing, and effort. The results were anything from a gentle boost as I pedaled on the flats to ripping up a hill at speeds that made me a hazard to my fellow cyclists.

What follows is a quick look at both the bike and the pedal-assist experience.

Credited with the assist

The bike that I got to ride is the newest version of Trek’s line of pedal-assist electric bikes, called the Allant . This is its first version with a battery integrated into the frame — it can either be charged in place, or you can use a keyed release system and built-in carry handle to bring the bike to charging hardware. The integrated battery is (Wh, and an additional) Wh can be attached to the outside of the frame to provide extended range. Among other things, that battery runs some always-on lights (with brightness adjusted thanks to an ambient light sensor) and a built-in display. The Allant will also charge your smartphone as well as communicate with the phone through Bluetooth, allowing it to replace the minimalist display that’s built in.

The smartphone software is designed to work with a series of switches that can be conveniently operated from the handlebars of the bike, a bit like the switches on the steering wheel of many cars. The parallels to cars extend further, as the system can be used to have the phone display basic performance numbers, navigation, to control music playback, or even to make phone calls to people on your contact list. Those latter two would be fine on quiet roads but aren’t ideal for urban rides, where headphones often limit riders’ awareness of their surroundings.

But the main thing the battery is for is to power a motor embedded where the cranks meet the Allant ‘s frame. The new models all use an updated version of the motor that Trek sources from Bosch, one that’s more compact and lightweight than its predecessors while still delivering (Nm) 55 lb-ft) of torque. The motor is designed to only work when the pedals are being moved (hence “pedal assist”) and cut out in the area of ​​ (mph) (km / h). This cut-off limits the maximum speed you can go without working (the limits are based in part on European regulations that have also been adopted by many states in the US).

      

  

But 28 mph is still impressively fast for a cyclist, and it required Trek to make adjustments to some of the rest of the bike’s components. The braking system is one that the company uses in the mountain bikes it specs for downhill racing, and the tires and wheels are more robust than it would use on a standard commuter bike.

All of that hardware comes at a significant cost: weight. While the exact details vary based on the frame material (aluminum and carbon fiber are options), geometry, and components, at a minimum this bike weighs over (lbs) (kg). That’s more than twice the heft of a mid-range road bike, which obviously contributed to the need for the Allant ‘s hefty stopping power.

Eco to turbo

My expectation for something called pedal assist was fairly literal: a constant boost that makes each turn of the pedals go a little further . That expectation proved to be dramatically wrong. To begin with, the Allant offers four levels of assist. In eco mode, torque- and crank-rate sensors figure out how much power you’re putting in and add an extra 50% boost to that. By the time you hit turbo mode, the motor adds twice the power that your pedaling is putting into the bike.

But the Allant isn’t entirely that simple. As described by the Trek representative, the electric motor has a sweet spot where it can transfer power most efficiently. Stray too far off the sweet spot by pedaling too quickly or slowly, and you’ll find yourself putting a lot more into the bike to hold the same speed. Adding an extra layer of complexity is the huge range of gears available on the bike, which can radically change how fast you have to pedal to maintain the same speed with the motor off.

The net result: there is a large range of experiences to be had with the same bike. Set the Allant in eco, crank up the gear ratios, and you can find yourself pedaling slowly but exerting most of the force that moves the bike forward. Pop it into turbo mode and change gears, and you can easily find yourself pedaling furiously but doing little more than cueing the motor into how fast it should be turning.

Some getting used to

I have no doubt that, with some experience, a rider could easily develop a feel for how to get the ride they want out of the bike. But the loop around Central Park is only six miles long, and I instead found myself wandering into and out of the sweet spot haphazardly. I frequently forgot to shift because the usual cues I use to determine when to do so simply didn’t apply to this bike. This was considerably less disorienting in eco mode, though, which could probably be used to provide a gentle introduction to pedal assist for people accustomed to motorless bikes.

A number of things were clear to me, though. Given some flat pavement and turbo mode, it was comically easy to reach the speed where the motor cut out, something I can’t do on a traditional bike. The north end of the park also has a hill that’s steep enough to cause inexperienced riders to give up and walk their bikes; the Allant blasted upwards as if the ground were flat, forcing me to weave around the bicyclists who were slogging their way up. On the weekend, when the park is far more crowded, it would have been dangerous.

The heavy frame also seemed to help hold momentum a bit better as downhill sections flattened out. The robust wheels and frame also did a lot to soften some of the bumps typical of NYC pavement, something I confirmed by riding over a section of road that I normally do my utmost to avoid.

Easy rider

Let’s be clear: I don’t belong to any of this bike’s target audiences. The vast majority of the cycling I do is to ensure I get exercise. As such, there’s little point for me in having anything that means I make less effort than I’d otherwise need to. And I didn’t have enough time with the bike to get a good feel for how to ride in a way that played to its advantages.

All that said, it’s hard not to be impressed by the package Trek put together. The bike is well-constructed and behaves just as advertised, the software is easy to set up and use, and there are all sorts of nice touches, like having three different flavors of cable that could charge any Apple or Android phones as you ride. The Allant is expensive — even the lowest-end aluminum-framed version costs far more than many excellent road bikes. But for the right person, it may be worth the price tag.

What person might be right? There’s also an argument to be made that the Allant would make an excellent commuter bike for someone who has access to bicycle storage at their work or school. Countless times over the years, I’ve found myself cycling while reminding myself that I did not want to arrive at my destination a sweaty mess. Invariably, I ended up chasing the feeling of acceleration and failing. The Allant seems to be able to take that decision mostly out of my hands; with the right settings, it would be hard to exert yourself enough to break a sweat on all but the hottest days.

But the most obvious audience is among the people who might have difficulty doing much on a bicycle otherwise: older riders, those with an injury, or anyone who simply struggles when they hit hills like the one in Central Park. To the extent that it opens up cycling to people who otherwise wouldn’t be able to enjoy it, the Allant is a great thing. But I don’t think it will prove a gateway to self-powered cycling. The experience is different enough, and the initial investment large enough, that people aren’t likely to put the Allant in storage in order to struggle up hills under their own power.