Fat tires and a motor make a new bike a veritable monster truck. The Electric Fat Bike, sold by Defiant Bicycles, is a niche offering that rides faster than anything in its class.

The speed comes from a motor in the rear hub. But there is no throttle on the handlebars – a pedal-assist feature adds power as your feet crank and spin.

With 4-inch-wide tires, the bike can mow over stones and “float” in snow. Fat bikes are notoriously tank-like, and this model, at 50 pounds, is no exception.

The 500-watt motor is added to overcome the mass, and a rider can crank easily to 20 mph on a Defiant bike.

A big battery attaches to the frame. A dashboard display reveals speed, power outage (in watts), and battery life.

In its highest settings, the battery lasts a couple of rides, roughly 25 miles in my test.

E-bikes and pedal-assist motors are not a new thing. But Defiant touts this model – both fat-tired and electric – as the first commercially-available bike of its kind.

Part dirt bike, part bicycle; the e-fat goes really fast, really easily. You get this pedaling bliss for a healthy $3,500.

Who should buy the Electric Fat Bike? The company sells it as a car replacement for anyone looking to bike commute and arrive at the office sweat-free.

It’s overkill for pavement and most cities. But the bike could be a good pick for commuters in northern climates, where snow keeps most riders off the road.

For singletrack and mountain biking, a possible buyer is someone with compromised physical ability. The “assist” on the bike will enable anyone with bad knees or other issues to keep up with younger and healthier riders.

A final candidate is someone looking straight up for pure fun. This bike brings huge smiles quickly to anyone who hops on. The big tread, wide grip, and motor-enhanced, plow-through-it-all experience made me feel like a rolling god.