The cheapest full-suspension fat tire electric bike? Testing this odd-looking entry-priced e-bike

While electric bikes are loads of fun and make for great utility riding, they aren’t known for being cheap. Adding extras like fat tires or full-suspension only send the price higher. So I wanted to see how good one of the cheapest full-suspension fat tire electric bikes on the market could be. And to do so, I turned to the Aostirmotor S18 e-bike.

Aostirmotor S18 tech specs

  • Motor: 750W rear hub motor
  • Top speed: 45 km/h (28 mph)
  • Range: 25-70 km (15-44 mi)
  • Battery: 48V 11.6Ah (557 Wh)
  • Max load: 136 kg (300 lb)
  • Weight: 36 kg (80 lb)
  • Frame: 6061 aluminum
  • Suspension: Front and rear
  • Brakes: Mechanical disc brakes
  • Extras: 7-speed Shimano drivetrain, LCD display with speedometer, battery gauge, PAS level indicator, odometer, tripmeter, headlight, frame-integrated tail light, included fenders

Aostirmotor S18 video review

They say that seeing is believing, right? If you want to see me testing out the Aostirmotor S18 while you get an up-close look at the bike in action, watch my video review below.

Cheap thrills, in every sense of the both words

The Aostirmotor is priced at $1,599 on the company’s site (and is sometimes on Amazon but seems out of stock there right now), which makes it one of the lowest-cost full-suspension fat tire e-bikes I’ve seen.

As you would imagine, that also means that the bike doesn’t come with the fanciest parts, but I found that the bottom-shelf components still made for a fun ride, even if they take a bit of getting used to.

Let’s take a quick look at the sacrificies that were made before we dive into the ride experience.

While the bike is full-suspension, neither the front nor the rear suspension are high quality. The Zoom fork isn’t the cheapest out there, but it’s not a luxury part by any stretch of the imagination. The rear suspension is basically just a spring. It means that big bumps don’t send the saddle into your lower intestine, but it doesn’t provide real dampening like you’d expect of a high-dollar electric mountain bike.

The brakes are pretty basic and the rear caliper doesn’t bite the disc nearly as hard as in the front. That can be common with mechanical disc brakes since the rear has a longer cable and more stretch, but the Aostirmotor S18 had ever weaker rear brake performance than I’m used to. The brakes still stopped me just fine, and its true that somewhere around 75% of your braking power on a bike comes from the front brake anyways, but the soft rear brake was still a bit of a bummer.

And the last major sacrifice were the ultra-cheap fenders. They flop around, especially in the rear, and generally just make a bunch of noise. They do their job too, but they aren’t high-quality wheel-hugging fenders either. The cheap plastic may stop water and mud spray, but they don’t inspire confidence.

As a side note, the bike is heavy as hell. At around 80 lb (36 kg), have fun loading it in the back of your truck. If you live close to your favorite riding location then this likely won’t matter much to you. But for anyone who transports their e-bike often, note that this is definitely not a lightweight e-bike.

But now that we’ve got those cheap parts and few downsides out of the way, we can focus on what the bike does well. And it definitely still has much to offer.

The far tire e-bike has a powerful 750W rear hub motor that blasts me up to 28 mph (45 km/h) with either throttle-only operation or pedal assist. You can of course ignore the throttle if you want to use the pedal-assist only functionality.

The giant tires are a brand I’ve never used before (Chaoyang), but they worked just fine for me. The large air volume supplements the mediocre suspension and makes for a pretty decent ride – certainly better than a hard tail mountain bike. Or at least more comfortable, as “better” is a bit loaded. Obviously you won’t have the same nimble ride as a mountain bike since the heavy fat tires aren’t nearly as responsive, but the bike still remains fairly sporty thanks to the shorter frame. I’ve reviewed giant fat tire full-suspension e-bikes that tend to feel more like a land yacht, and the Aostirmotor S18 definitely felt more nimble by comparison.

The bike also sports a very novel-shaped battery in its novel-shaped frame. Two locks (one electrical/mechanical and one purely mechanical) hold the battery case into the center of the bike. There’s a little handle on top that lifts up to pull the battery out once you’ve unlocked it, making the process easier.

The case is a bit odd, but I’ll give the company style points for using a new battery shape instead of repurposing one of the half dozen common designs we see on every budget e-bike.

The 557 Wh battery gives a sufficient range of around 15-20 miles (25-32 km) on throttle-only riding if you’re being reasonable with the throttle, and you can eke out more range if you add some old-fashioned pedaling. But this isn’t a high-capacity batter – it’s a good enough battery.

Another note about that odd-shaped frame wrapped around the battery is they use it to integrate the rear tail light directly into the frame. I’m actually a fan of that method because its one less component to break off. It ensures that the light will also function since it runs off the e-bikes main battery. Having to swap out AAA batteries in bicycles lights or recharge them on USB is a big pet peeve of mine.

There’s a typical LED headlight up front like you’ll find on most basic e-bikes. Nothing fancy, but it gets the job done. The fact that there are built-in lights at all though is a nice addition to add commuter functionality to what is likely to be a dual-purpose bike for many people. While the Aostirmotor S18 definitely works for trail riding, a lot of riders enjoy fat tire e-bikes and full suspension models for road riding. The same features that make them great for trails (suspension and fat tires) also make them great for urban obstacles like pot holes and curbs.

Given that the Aostirmotor S18 isn’t a highly tuned off-road machine, this dual purpose use seems appropriate for it.

If all I wanted to do was ride trails all day, I’d choose a higher quality dedicated electric mountain bike.

If I only wanted to commute, I’d go for a purpose-built commuter e-bike.

But if I wanted to get into varied e-bike riding with a fun full-suspension fat tire e-bike for a much lower price than these bikes tend to command, the Aostirmotor S18 would be a good choice.

It’s a great beginner fat tire full-suspension e-bike for anyone that doesn’t want to part with several thousand dollars in one go.

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Avatar for Micah Toll Micah Toll

Micah Toll is a personal electric vehicle enthusiast, battery nerd, and author of the Amazon #1 bestselling books DIY Lithium Batteries, DIY Solar Power, The Ultimate DIY Ebike Guide and The Electric Bike Manifesto.

The e-bikes that make up Micah’s current daily drivers are the $999 Lectric XP 2.0, the $1,095 Ride1Up Roadster V2, the $1,199 Rad Power Bikes RadMission, and the $3,299 Priority Current. But it’s a pretty evolving list these days.

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