So what exactly is a fat tire electric bike? Simply put, it’s any ebike with tires that are 4+ inches in width. Most fat tire ebikes have 4” tires, but some have 4.5” and even 4.8” widths, which are also referred to as super fat tires. By contrast, conventional bike tire widths from 1.95”, 2.0”, 2.1”, 2.3”, to 3.0”.
Not your typical fat tire electric bike
The most common diameters of bike tires are 20”, 24” and 26”, but the common variable for fat tires is their 4” or greater width.
Unlike conventional tires, fat tires can be ridden at varying pressures, measured in pounds-per-square-inch (psi). Most fat tires can be inflated from 5psi to 30psi, allowing you to adjust the tire pressure to suit surface conditions. On a paved road, a tight 30psi tire will work best, but if you are on soft surfaces such as wet sand or snow, lowering the psi will increase surface area contact and provide more float.
Fat tire ebikes come in several styles, including ones with step-thru frames, folding frames, and perhaps the most common, fat tire electric mountain bikes. Once again, the common variable is tire width.
The larger rims and wider tires typically add about 4 pounds to the bicycle's weight. This can be reduced with rim cutouts, which reduces the mass of the rim. Four pounds may not seem like a lot, but that is on top of the added weight of the motor, battery and controller.
So fat tire ebikes are generally heavier than other ebikes, and definitely heavier than conventional bikes. This will not be an issue so much when riding, but it can be a problem if you need to lift your bike onto a rack or carry it up and down stairs.
Fat tires have a bigger footprint than conventional tires. There is more surface area contact, and this is true whether you are riding on a paved road, a gravelly and rutted trail, or through a snowy field or sandy beach.
The greater amount of surface area contact has several benefits, including more stability and great traction. You can think of it like shoes on your feet. Which shoe gives you better stability and traction, a hiking boot or a high heel?
From a technical perspective, the friction between your tire and the road is known as rolling resistance. The greater the friction, the slower you will go. Poor road conditions, lower quality tires and tubes, rider weight, and speed, all contribute to adding friction and thus slow you down.
Stability is important on both paved and unpaved surfaces. On paved surfaces, stability in turns can prevent the bike from losing its grip and sliding out from under you. On unpaved surfaces, stability will help you maintain your balance as you encounter changes in surface conditions, like ruts, stumps and rocky lines. Having greater traction is also a benefit, since it will prevent slide-outs and transfer more of the motor power directly through the drivetrain to the riding surface.
Another benefit of fat tires is their ability to work effectively on soft surfaces, including snowy and sandy conditions. This is sometimes referred to as floatation, or the ability of the tire to float over rather than cut through the soft material. This is best achieved when you deflate the tire pressure down to as low as 5psi. The bigger footprint of a fat bike tire distributes the load over a wider patch of ground, allowing you to ride over terrain that would be impossible on a regular bike, like loose sand and snow.
Over a snow-packed single track, riders can glide through icy corners that may have sent them hurtling to the ground on a standard mountain bike. The squishier tires can also make for a much more comfortable ride on the trail. On sandy beaches, fat tires will ride over the surface more than cutting into it.
But other factors also play a part, including the weight of the rider and how much motor power they have on their bike. Snow drifts and thick dry sand will still require some muscling through, even with the help of a powerful motor. You're definitely going to get in a workout.
Rocks and roots that would rattle your brains on a regular bike are now barely felt under the cushion of your big tires. Everything seems muted, which can be a negative for some people as you have less feedback. You feel somewhat invincible descending over chunky stuff. People with back problems can find fat bikes much more comfortable because of this.
It can make your line choice sloppier then before though. Sometimes I will see that I am headed towards a choppy or nasty line that I wouldn’t normally take, but with the fatty plow right through. Having said this, tire pressure on a fatbike is absolutely critical, more so than any other bike. One or two psi over your ideal pressure and your ride will feel harsh and bouncy, too little and you will run into more rolling resistance than necessary and risk damaging your rims.
The low pressure tires enable it to grab on to the terrain better. I use about 7 psi on my fat bike when riding regular trails and the tires just conform to every irregularity on the terrain, making climbing traction seem almost unlimited. Cornering traction can also be vastly superior vs. other tire sizes but the big tire can also work against you here, it will depend on the type of soil and terrain.
Wow factor is also a big plus if you are into that. No other bike will draw as much attention as a fat tire ebike, especially from non-cyclists.
Fat tire electric bikes do have their disadvantages, and you should be aware of these before getting one.
First, fat tire bikes are heavier than their conventional counterparts, especially when they are used as heavy-duty mountain bikes. They can weigh anywhere from 60-80 lbs, compared to regular ebikes which typically weigh 45-60 lbs.
The greater weight is due to the greater mass of the larger tire and rim, and in the case of mountain bikes, the heavier gauge frame and components. The extra weight may be noticeable if you are riding up hills without a boost from the motor, but less so on flat paved roads. The heavier bike will also be harder to lift onto a bike rack, or to carry up and down stairs.
Second, the unique combination of the relatively heavier frames, decreased tire pressure and rolling resistance can result in fat tire bikes feeling slower and more sluggish compared to other models. Of course, with a motor on board, this isn’t really a problem, but it can be noticeable if you are only using the standard gears to propel the bike, especially on uneven surfaces or hills.
Another potential downside to fat tire bikes is the flip-side of one of their advantages: floatation. While the ability to float over soft surfaces is great, in certain muddy situations you could find yourself with less grip or bite than with a narrower tire.
Fat bike tires can be tricky to ride on some gravelly surfaces, especially if the tire is not well manufactured with good tread and sidewalls. With the larger surface area contact, there is the potential to become destabilized if you hit some gravel, where the small rocks can act like ball bearings and decrease friction.
Finally, since fat ebikes are not as popular around the world as typical bikes, riding a fattie will always cause a flurry of excitement and attention with onlookers wanting to check out your awesome ride. While this may sound like a remarkable thing, it can, however, attract the wrong crowd, which may put you at greater risk of theft.
Fat tire electric bikes fall into several common bike formats, including mountain, step-thru and folding.
Fat tire electric mountain bikes have the typical characteristics of conventional mountain bikes, including an aggressive, forward-leaning body posture, straight handlebars, heavy-duty frames, and front shocks. Some fat tire ebikes have full-suspension frames and hydraulic disc brakes.
Fat tire ebikes with a step-thru frame are less common, but there are a few that are very popular with customers. The E-Fat-Step is our bestseller in this category. It features a curved frame that allows for easy mounting and dismounting. The E-Fat-Step also sports 20” x 4” tires and is a folder, so it's more portable than other ebikes in this category.
Finally, there are a wide range of fat tire folding ebikes on the market today. This is one of the most popular categories, with new models being introduced on a regular basis. Fat tire foldable ebikes typically have 20” x 4” tires, and feature a central hinge and clamp folding mechanism. Some also have a fold tiller, which reduces the overall folded dimensions and makes the bike more portable.
In this category, the Big Dog Extreme by GreenBike is our most popular model. It features a powerful 750W rear hub motor, an easy access long-range battery, magnesium alloy rims, hydraulic disc brakes, and essential accessories such as fenders and a rear rack.