Good grief, some of the information passed on. Most of it is good, alot misinformed!
Scramjett: I'm the owner of two fatbikes. The first, a Specialized Fatboy. Hard tail, no suspension save for the Cane Creek Thudbuster LT I installed. 4.6 inch wide tires, ridden up to 20 psi on asphalt roads. I have about 4000 miles on my Fatboy; bought new.
My other bike, which has effectively knocked out further use of the Fatboy, is my Haibike Full FatSix. One of the premium fatbikes out there, with top tier components compared to that Bixtrix fatbike mentioned elsewhere. Yamaha PW drive. Fully decked out by me with front and rear racks to accomodate all kinds of Ortlieb bags for day rides or touring. Front Schmidt SON28 dyno hub powering up a front German made Schmidt Edelux II headlight and Schmidt Son rear tail light. Tubeless tires. Cane Creek Ergo bar ends on a 60mm riser bar by Spank. Ergon saddle. Abus Bordo lock.
With that out of the way, I ride this bike anywhere, anytime, any condition except water fording. As it should be with any other ebike.
The Fatboy convinced me I could ride this bike on asphalt, albeit it's gonna be averaging about 13 mph. But no bike ever made me smile as to the "feel" of the bike when starting out on every single ride.....there is simply no substitute for the feeling of control and stability on the fat tires. None.
Unlike skinnier mtb tires, my fatbikes easily go through the deep sugar sand of the New Jersey Pine Barrens. THIS is where a fatbike really shines, sugar sand and snow. It's just a matter of airing down to 6 or 8 psi and you are good to go. Done with the deep sand? Air back up and bike on!
Truth is, most of my miles accumulated on the Haibike is on asphalt roads. Last count, 9400 miles on the odometer after putting her into full time service in the late spring of 2017. Asphalt roads mean nothing with this Yamaha ebike drive. In the height of summer when I am in the best of cycling shape, I can linger at 19-20 mph at the motor cutout on a 16mph plus average speed on a 20 mile run that I typically make.
Any ideas of a fat tired ebike not good on riding asphalt roads is rubbish. This past summer, I ebiked the Full FatSix from home on the western side of NJ, to the east coast of NJ at the Atlantic Ocean, then turned around back home. Summer time, 90 degrees plus, 95 miles. All on asphalt.
A fat tired ebike can go anywhere a mtb can go....and then some. It may not be faster (who really cares about that?) or lightning twitch-quick maneuverable on some Alpine Pass (who really goes down that stuff on a forum such as this one?); but it is like a Jeep Rubicon of all bicycles, hands down. The Rock Shox front and rear suspension on the Haibike takes out the dips and crowns of the local roads I ride here in NJ. Suspension on high end bikes are nothing like the dual suspension bikes that first came out in the 1990's. They are a real game changer in rider comfort!
Some pics of the Fatboy and the Haibike Full FatSix......