Two big trends that have stormed the bicycle industry over the past few years are pedal-assisted electric drivetrains and fat tires. These two trends converge in Defiant Bicycles' Big Easy. Unlike other electric bikes that stop at the edge of the street, the Big Easy keeps rolling over some of the toughest, most sluggish terrain on Earth – everything from hot sand to cold, mushy snow.

We've seen a few different electric fat bike designs in recent years, including 20-inch-tired clown bikes from Hanebrink and the Pedego Trail Tracker. We expect to see more of these bikes emerge because many US cities with big bike cultures – Portland, New York, Boulder and Minneapolis, to name a few – can have harsh, snowy winters. An electric bike designed to excel in snowy weather seems like a natural fit for commuters in these types of locations.

In fact, the Big Easy was created by a dedicated Minnesota cyclist to fill just that type of niche. Defiant co-founder Kevin Spreng, a Twin City-area attorney, became frustrated by the lack of viable winter commuters so he set out to design his own.

"I thought I’d give a fat tire snow bike a try," Spreng explains on Defiant's CrowdSupply campaign. "It worked great on snow and ice, but it wasn’t fast enough for me. So, I put an electric motor on my snow bike. It was brilliant. Now I could go 15 to 20 miles per hour on snow-covered trails and roads while still getting a terrific workout. That’s really how Defiant Bicycles and the Big Easy model were born."

With its 4.7-inch tires, the Big Easy is among the "fattest" of the fat bikes on the market. Those fat tires can be deflated to pressures as low as 7 psi, increasing their surface area to better "float" through soft terrain. Big, cushy tires also add a sort of suspension system, smoothing out bumps and ruts.

While its burly build and big tires are all about rough weather, its e-assisted drivetrain is aimed at sure-footed, reliable commuting. Electric bikes like the Pedego Trail Tracker make riders choose between motored propulsion and pedaling, but the Big Easy uses a pedal-assisted powertrain that provides an extra boost to get riders from point A to point B a little faster, with a little less effort. Motor assistance can also be useful for carrying heavy gear or helping the rider muscle through a particularly tough, sticky track of snow.

The drivetrain combines a 500-watt rear hub motor and frame-mounted 36-volt lithium-ion battery, offering enough power for 20 miles (32 km) of range and 20 mph of speed. The pedal-assist motor output can be adjusted at the push of a button. The rider can also pedal the bike without any motor assistance and has nine speeds at his disposal. The 8.5-lb (3.9-kg) battery, which takes about four to five hours to charge to full, can be removed completely to create a lighter set-up.

A fat e-bike may be most at home in the slush or sand, but Defiant's idea was to build a bike that could excel all year, in all types of conditions, not just in the winter or on the sand. It claims the bike is a year-round workhorse and recreational steed for mountain biking and commuting. It's also marketing the bike at hunters, adventure tourers and other cyclists that cover a lot of ground with an abundance of gear.

Defiant is currently trying to raise funds on crowd-sourcing site A Big Easy with a 6061 aluminum frame (built in Portland, Oregon), Shimano XT components and disc brakes is being offered for US$4,495. That's well over the price of the Trail Tracker but competitive with a Surly Moonlander outfitted with a comparable electric motor system. Other Defiant models are available for preorder on the company's website.

View gallery - 5 images