Pedaling an electric mountain bike is a workout, not an effortless romp, requiring almost as much physical exertion as riding a standard mountain bike. But the effort feels easier on the e-bike, according to the first study of motor-assisted mountain bikes and how they affect the physiology and attitudes of experienced cyclists.
The study suggests that e-mountain bikes might enable many riders, including newcomers, to maintain or gain fitness while transiting otherwise daunting hills, snowy trails, spins with spouses and daily commutes. The findings do raise a red flag for the unwary, however, since the speeds attainable on motor-assisted bikes can be high.
Electric bikes, known as e-bikes, are increasingly common on streets and bike paths, both in the United States and elsewhere. Equipped with a small electric motor and battery, pedal-assist e-bikes provide an extra little zap of power as you pedal, about like the nudging of a gentle tailwind. (“Throttle-assist” e-bikes power the bike even when you are not pedaling and are more akin to motorcycles than bicycles.)
E-mountain bikes, like most standard mountain bikes, differ from the versions designed for roads by sporting wide, knobby tires and other features that make them suitable for riding on dirt trails, over snow, or in similarly ungroomed conditions.
The allure of both road and mountain e-bikes is obvious. With the pedal-assist, which usually can be adjusted up or down to suit someone’s fitness and preferences, they make hills feel flatter and distances shorter. The extra boost may encourage people who are out of shape, inexperienced or entering or exiting middle age to cycle.
A few small past studies have found that riding a road e-bike also constitutes hearty exercise. In a small 2016 study in Boulder, Colo., researchers found that commuting on an e-bike for a month increased new riders’ fitness and improved their blood-sugar control. Most of the volunteers also accumulated more time in the saddle than had been asked of them for the study, presumably because they were enjoying themselves.
But little has been known about whether e-mountain bikes likewise provide a robust workout or whether riders will like them. So, for the new study, which was published in August in JMIR Formative Research, researchers at Brigham Young University in Provo, Utah, determined to find out.
They began by recruiting experienced local mountain bikers, in part because, should these riders work up a sweat on an e-mountain bike, newcomers to the sport would likewise be expected to get a meaningful workout. The researchers also were interested in the riders’ attitudes toward pedal-assisted mountain biking and whether the riders felt that e-bikes might make the activity somehow too easy.
They wound up with 33 riders, mostly men, from age 18 to 65, all of whom turned up on separate days at the trailhead for a rolling, six-mile, single-track loop. There, they completed several questionnaires about their beliefs about e-bikes, strapped on a heart rate monitor and activity-tracking watch and rode the trail astride either a standard mountain bike or a comparable e-version. After a rest, they repeated the loop on whichever bike they had not ridden before. At the end, they filled out the questionnaires again.
It turned out that riding an e-mountain bike had confirmed some of the cyclists’ expectations an subverted others. More of the riders felt afterward that pedal assistance would make riding appealing to average people and fewer suspected that e-mountain bikes would be a passing fad.
Meanwhile, their personal, physiological responses to the riding proved to be complex. The cyclists had been swifter with pedal assist, about four miles per hour faster on average, but reported that the e-riding felt less taxing, physically. At the same time, their heart rates rose to and remained at about the same level during both rides.
In other words, the pedaling assist had lessened how draining the riding felt but not how much exercise it actually provided, says Cougar Hall, an associate professor of public health at B.Y.U., who oversaw the new study with his colleagues Benjamin Crookston and Joshua West, all of them avid mountain bikers. (The study was funded by the university, which purchased the necessary e-mountain bikes.)
That dichotomy between the perceived and actual effort involved in the riding might make e-mountain biking practical for and attractive to new riders hoping to pedal into shape or keep up with practiced trail-riding partners, he says.
“If these bikes can be a catalyst to get people outside and riding trails that they might have thought were too intimidating, that’s a victory for them and for public health,” he says.
This was a small, very short-term experiment, though, involving a single e-ride on one forested trail by accomplished mountain bikers, most of them men. Results might be different for riders who are female, inexperienced or who live in cities.
E-mountain bikes also tend to be pricey, and their top speeds, which can exceed 20 miles per hour — at which point, the bikes’ motors are designed to switch off — may be alarming. Dial down the amount of motorized assistance if you wish to maintain a sedate pace and not outstrip riding mates, Dr. Hall says.
He also suggests that if you have never tried an e-mountain bike and are curious, check with local bike shops about rentals, demo days or the possibility of briefly testing a model or two on a nearby trail.