Riding an electric mountain bike for the first time feels like having a superpower.

It’s just so otherworldly, the sudden, silent surge that sends you flying uphill while you pedal with minimal effort. As a tech product, these “pedal-assist” bikes are flat-out impressive.

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But as an increasingly popular phenomenon, they raise a host of issues. And as their numbers on Bay Area trails grow and land-use officials ponder restrictions, conflict and controversy are bound to follow.

I decided to hit the trails for a couple hours recently, alternating between an electric bike powered by a 250W Bosch motor with a lithium battery and a traditional full-suspension mountain bike.

I found the motorized technology simple to operate — a push of a button on a handlebar-mounted controller lets you power up and down through five settings, topping out at “turbo.” The motor only kicks in when the rider is pedaling.

Using turbo and ascending a moderate hill, a few strokes of the pedals triggered a rocket-like boost, while the lower settings required more leg power. Still, even on turbo, a particularly steep grade required an effort that had me huffing and puffing, although to a considerably lesser degree than on my regular mountain bike.

And on bumpy medium-grade hills, the power-assisted riding was relaxing enough for me to gobble a chicken sandwich, slurp cherry ice cream and even enjoy a refreshing bottled beverage.

Downhill, the bike’s 48-pounds, 29-inch wheels and front-and-rear shock absorption made for a smooth ride, though the weight meant the bike was harder to maneuver than a traditional mountain bike and felt slightly less nimble. The motor sits at the bottom of the bike, where the pedal cranks attach, and the battery is mounted on the frame in front of the motor.

With a 30-mile range on turbo and 90 miles on eco — after a full three-hour charge — I had little worry that I would run out of juice. A spare battery costs upward of $700, so riders tend to stay within range, keeping an eye on the charge-indicator lights on the battery, rather than carrying an extra power pack.

So far, the bikes’ debut onto California trails has met with little overt resistance — even the Sierra Club has declined to take a position. But many trails remain closed to the bikes, and rumblings of discontent from traditional mountain bikers and official reviews underway foreshadow future trouble.

Legendary mountain bike builder Richard Cunningham of San Diego said he’d ridden electric mountain bikes and found them “absolutely fun.” But he still doesn’t want them on trails.

Mountain biking, he said, is difficult

“If it was easy, everybody would be out there. It makes the backcountry unpopulated, and that’s why we go out there,” Cunningham said. “We go out there to disengage, and not to defend ourselves against another technology.”

“It’s going to put pressure on the trails, for sure,” he added.

One rider who might not be on the trail without an e-bike is Bob Widinski of San Rafael, who in his younger years spent a lot of time riding traditional mountain bikes in Marin County. Now, he’s 72, and started riding electric mountain bikes five years ago.

“I’ve just gotten to the point that it’s difficult for me to ride some of the trails because I don’t have the lung capacity that I used to have,” said Widinski, a wine-industry consultant. “I can get back on the trails that I used to ride. I enjoy riding again, so much. It always brings a smile to my face.”

At the Motostrano shop in Redwood City, owner Joe Witherspoon has been selling electric mountain bikes for about three years, and sales have doubled to more than 200 per year. His average buyer is male, aged 50 to 55, Witherspoon said.

“They’re folks who look at a time when they can’t ride. Or they haven’t ridden for 20 years and they’re out of shape. They don’t want to get ready for three years before they do this,” he said.

E-bike prices at Motostrano range from $2,500 to $16,500. With most manufacturers using Bosch motors, price differences have more to do with the frame, suspension and components such as brakes, cranks, wheels and shifters. So far, only one buyer at Motostrano has coughed up for the priciest model, made largely of carbon fiber. The purchaser was “an Arabian sheikh” who bought two of the bikes, which are made by Germany’s Haibike, Witherspoon said.

It’s not necessary to shell out thousands to sample the electric mountain bike experience — Motostrano is one of several Bay Area shops that rent the machines, typically for $100 per day and up. Motostrano loaned this newspaper a $4,400, German-made Cube “Stereo Pro 120” electric mountain bike for our trail test.

The bikes aren’t welcomed everywhere. Authorities for some trail areas in the Bay Area, including the Midpeninsula Regional Open Space District and the East Bay Regional Park District, put electric bikes in the same category as motorized vehicles such as motorcycles, and prohibit them on trails.

“There are two-and-a-half million people in the East Bay. Some of our trails are very crowded,” said East Bay parks spokeswoman Carolyn Jones. “We have horseback riders, joggers, people with strollers, people in wheelchairs, we have hikers, bicyclists, dog walkers. It’s just a safety issue. We already have enough problems with collisions and conflicts.”

In California state parks, including Mount Tamalpais and Mount Diablo, electric mountain bikes are considered bicycles and allowed wherever traditional bikes are permitted — but local park administrators have the power to ban them and rangers can issue citations for unsafe use. And state parks officials at the state and local levels are “looking at e-bikes because it is a new technology, and determining if there will be… restrictions,” said Ryen Goering, superintendent at Mount Diablo.

Electric mountain bikes appear to cause significantly less environmental disturbance than motorcycles. Research by the International Mountain Bicycling Association found impacts in line with those from traditional mountain bikes.

“What is harder to measure and what is a bigger concern is the social impact of sharing the trails with electric mountain bikes,” said association spokeswoman Eleanor Blick. Traditional mountain bikers, Blick said, may not appreciate having to get out of the way while “climbing up some awful hill” so “someone can just cruise by on a pedal-assist bike.”

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Trail test:

Bike: German-made Cube “Stereo Pro 120”

Wheel size: 29”

Front and rear suspension travel: 4.7”

Weight: 48 pounds

Motor: Bosch mid-drive 250W

Battery: lithium

Brakes: hydraulic disc

Manual gears: 11

Power-assist speeds: 4 – “Eco,” “Tour,” “Sport,” “Turbo”

Range under power: 30 to 90 miles, depending on power-assist setting

Charge time: 3 hours

Plugs into: household outlet

Price: $4,399