The most in-demand ebike category is fat tire electric mountain bikes. These types of bikes can be ridden pretty much anywhere, from paved city streets to hardcore off-road trails. The fat tires are also ideal for riding through sand and snow, especially if you have a powerful electric motor onboard.
We wanted to dedicate a complete article to the Aostrimotor Ebikes brand, because they specialize in designing, engineering and developing some of the best electric mountain bikes on the market today. And they do this at incredibly affordable prices.
If you’re in the market for an electric mountain bike, and would like to learn more about leading budget brand Aostirmotor (pronounced O-Stir-Motor) then hop aboard and let’s get rolling.
The bikes reviewed in this guide include models:
We’re starting our lineup review with the fleet leader, the S18-1500W Fat Tire Electric Mountain Bike. This ebike is a full-featured, full-suspension, fat tire electric mountain bike, perfect for trail riding and hunting. The Aostirmotor S18-1500W is renowned for having a motor that twice as powerful as most other ebike motors used today.
The nominal output of this rear hub motor is 1500 watts, giving the bike incredible climbing and towing ability. Are you a big guy over 225 lbs? Are you gonna be hauling a quarry trailer? Then you should really consider the S18-1500W.
The heavy-duty 6061 aluminum alloy frame is full suspension, with a Zoom hydraulic fork with lockouts up front, and a strong spring absorber in the rear. The frame geometry is 100% unique to Aostrimotor, with aerodynamic lines and an integrated (removable) battery pack. Fenders are included.
The 1500W motor is paired with a long-range 48V/15Ah battery, housed within the frame of the bike. The battery can be removed for remote charging, and to protect it against weather extremes. Under averaging riding conditions, this battery pack should give you about 36 miles of range per charge. You can extend your range by moderating how much throttle and pedal assist you use, and by bring a spare battery to swap out.
The S18-1500W is comfortable to ride, although it does have a slightly forward riding posture and straight handlebars typical of electric mountain bikes. You can propel yourself under human power using the 7-speed Shimano drivetrain. And when you need a boost, you have access to a 5-level pedal assist system (PAS) and a right-side twist throttle. This will give you the ability to find the perfect combination of human and electric power for every riding condition.
Like the S18-1500W, the S17-1500W has a full-suspension, heavy-duty aluminum alloy frame, and a super-charged rear hub motor with a nominal output of 1500W and 80 Newton Meters (Nm) of torque.
In contrast, the S17-1500W sports a long-range 48V/20Ah battery, which should give the average rider almost 50 miles of range per charge. The battery is fully integrated into the unique bike frame, and can be removed for security and remote charging.
Another key difference between the S17-1500W and the S18-1500W are the wheel sets, with the former sporting 26” x 3” mountain bike tires and the latter featuring 26” x 4” fat tires. Deciding which tire format will work the best is really a personal choice. The narrower mountain bike tires will be more nimble and lighter weight; whereas the fat tires will provide more traction and stability.
Getting a tire with greater traction brings greater confidence, which translates to more fun and faster progression as a rider. If you have a need for speed, though, consider sacrificing a little grip to gain rolling efficiency.
The S18 all-terrain fat tire electric mountain bike has many of the same design features as the S18-1500W, including the unique full-suspension frame design, integrated/removable 48V/15Ah lithium-ion battery with Samsung cells, 7-speed Shimano drivetrain, 5-level pedal assist system, and right side twist throttle.
The essential difference between these two models is the motor output, with the S18 featuring a powerful 750W brushless rear hub motor and a max assist speed of 28 mph.
Like its namesake, the Aostirmotor S18-MINI has a uniquely styled full-suspension frame, pedal assist system and twist throttle. Where it differs is that it features 20” x 4” fat tires, with a 31” minimum seat height, lowering its overall profile and making this model more suitable for shorter riders. It also has a 500W rear hub motor, which is currently the industry average and still quite powerful.
The S18-MINI has the benefit of 4” fat tires, which have more surface contact with the ground, and offer more traction and stability when traversing unstable trails. These tires have variable inflation, allowing you to go from 5psi to 30psi depending on riding conditions and your personal preference. With the lower inflation level, the tires have more cushion, providing enhanced movement through sand, snow and other soft surfaces.
At full inflation, these tires will be more nimble, giving you confidence when racing down a rugged and rutted single track trail.
The LED display screen provides readouts for battery power, speed, PAS level, and mileage, and can be set for wheel diameter, mileage units, and riding mode. It also includes a USB for phone charging, and integrated front and rear lights, and fenders, come standard.
The Aostirmotor S05 and Aostirmotor S05-1 ebikes share their pedigree with the S18, with their curved full-suspension 6061 aluminum alloy frame geometry, aggressive mountain bike riding posture, and class 3 max assist speed.
Both of these models feature a powerful 500W DC brushless rear hub motor, which will provide the rider with lots of torque for hill-climbing and headwind fighting. The motor is powered by a 48V electrical system and a long-range 15Ah battery with Samsung cells. The key difference between these two models are the rims. The S05 has 26” x 2.5” spoked rims, and the SO5-1 has 26” x 2.5” blade rims. Spoked rims are most common, and allow for truing when the wheel gets out of alignment. By contrast, blade rims are stiffer and fixed in place, with no truing required.
The S05 and S05-1 feature a smooth shifting 7-speed Shimano drivetrain with trigger/click shifters, which allow you to ride them like a conventional mountain bike. The drivetrain is protected by a chainring guard up front and a derailleur guard in the rear. Located next to the gear shifter is the right-side half-twist throttle.
Like other Aostirmotor electric mountain bikes, the SO5 and S05-1 are capable of achieving a maximum assist speed of 28 mph, which is technically considered a Class 3 ebike in some jurisdictions. However, these bikes can be ridden wherever regular bicycles are allowed.
If you are looking for an affordable fat tire electric mountain bike, consider the S07-2 and S07-B models from Aostirmotor. Unlike the other ebikes reviewed above, the S07-2 and S07-B do not have full-suspension frames. They are outfitted with hydraulic front shocks with lockouts, and hard-tails (meaning no rear shock absorber).
These models feature heavy-duty aluminum alloy diamond shaped frames, with slightly angled top tubes and a forward riding posture. The slightly more expensive S07-B model comes with fenders and a rear rack standard. Both models come with integrated headlights.
The Aostirmotor S07-2 and S07-B both feature 750W rear hub motors, which will give the rider an incredible boost when using the pedal assist system or twist throttle. The S07-2 has a standard 48V/10.4Ah battery, whereas the S07-B has a 48V/13Ah battery for a longer range of travel per charge.
Both models feature a 7-speed Shimano Sunrace derailleur and trigger/click shifter on the right side next to the throttle. The chain shifts smoothly across the cassette, giving you the ability to ride like a conventional mountain bike with only human power to propel you on your ride. Both models also have a 5-level pedal assist system (PAS) with speed (cadence) sensor. The twist throttle allows you to riding without pedaling, which is nice at the end of a ride when you just want to enjoy cruising along.
The Tektro mechanical disc brakes have 180mm front and 160mm rear rotors for authoritative stopping power.
If you’ve made it this far, you might be wondering if Aostirmotor only produces electric mountain bikes. Well, the S03 is a Commuter Electric Bike, and one with very impressive specs for a sub-$1,000 model. The Aostrimotor S03 is ideal for riders who are new to ebikes, and want a simple, intuitive and affordable bike for everyday riding.
The Aostirmotor S03 City Commuter Ebike has 26” x 2.1” tires, which are designed for city riding and light trails. There S03 comes standard with an integrated headlight and fenders, as well as a chainring guard and derailleur guard.
The S03 operates at 36V and sports a high-powered 350W rear hub motor. This motor may not be a robust as those discussed earlier in this review, but it’s still quite suitable for city riding.
When riding the S03, you can use the 7-speed Shimano gears and propel yourself under human power alone. But when you need a boost, you will have confidence in the power of the 5-levels of pedal assist, and the freedom that comes from the twist of an ebike throttle.
Last but certainly not least, we have the A02, a super affordable fat tire folder. This ebike has a central folding mechanism (hinge and clamp), and the tiller also folds down, making the A20 highly portable and storable. This is a great ebike for RVers and other outdoor enthusiasts, as well as students and others who want a cheap and fun fat tire electric bike.
Riding a 20” fat tire ebike is so much fun, especially when you go off-road and tackle some gnarly trails. The A20 loves the dirt, and also performs well on loose surfaces like sand, snow and gravel.
Even though the Aostirmotor A02 fat folder is one of the least expensive ebikes on the market today, it still features a powerful 500W rear hub motor, a decent 36V/13Ah removable lithium-ion battery, 5-levels of pedal assist, and a precise variable speed twist throttle. There is also a 7-speed Shimano drivetrain, which allows you to ride the bike under human power.
The A20 has Tektro mechanical disc brakes front and rear, giving you strong stopping power when needed.
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