AIMA Big Sur U Review | E-Bicycle Built For Two

AIMA equips the Big Sur U with a 720Wh battery. It’s not a perfect 1:1 pairing of motor wattage to watt-hours, which is our ideal benchmark, but it comes reasonably close.

The brand claims a range of 20 to 60 miles depending on the usual variables: power level, rider weight, terrain, and weather. Those claims lined up with our testing. On our local bike paths, the Big Sur U covered 25.4 miles in the highest assist level. When we charged up and ran the test again in the lowest power mode, it traveled 59.9 miles. These results were achieved using the torque-sensor mode with a single rider; cadence mode or riding with a passenger would reduce those numbers.

The most important takeaway is whether the raw mileage fits your needs. If those numbers sound sufficient for your rides, great. If they fall short, don’t count the bike out. You can tune the motor’s behavior in the Bafang Go app to draw less power and stretch your range.

Our efficiency data came in around 12 Wh/mi in low assist and 28 Wh/mi in high assist. Comparable bikes tend to land closer to the 11 to 22 Wh/mi window. The Big Sur U’s lively power delivery uses a bit more energy, but you can dial it back in the settings if maximizing range is a priority.

If you’d like, I can also create a short “range test summary” version for YouTube or a callout box for the written review.

The Big Sur U is a utility bike, and those are built to be haulers, packing in high power and high torque hub motors. And it’s nice to have the option to hammer the throttle if you don’t feel like pedaling. Whether you like to climb yourself or let the bike do the work, it’ll be an easy experience up the steep slopes of the neighborhood.

On throttle power, the bike completed the test in 1:53 at 16 mph. Ran again with pedaling help and that improved to 1:46 and 17.1 mph.

Those are strong results. The all bike average is 2:00 and 2:07, respectively. Even if you narrow it down to fat tire or utility class standards, your looking at average or slightly above average results compared to its peer group.

750W of hub motor power with a 1200W peak and 85Nm of torque is good power. Those numbers are becoming more commonplace for this class and you can see why with results that can make an otherwise intimidating hill seem like just another part of the ride.

For your everyday hills, mid to high PAS levels will make hills all pretty easy. Lower power levels will provide noticeable help, with higher levels of rider input. I predominantly did my testing with the torque sensor, and can testify that it kicks in and notices your extra push on hills and responds well. Cadence-based riders will motor ahead pretty well, but won’t sync up as much if you want to do hill pushing (good or bad is eye of the beholder there).

Bottom line, I think this bike has plenty of muscle. The exact thing I’d hope to say for something you can ride with up to 100 pounds riding shotgun.

I expected good results, but these were all-timers. A stopping distance of 16 feet, 4 inches is the fourth-best we’ve ever recorded. After nearly 300 of these tests, that’s saying something. The ingredients were all there: shorter tires, a low center of gravity, larger rotors, and rubber that isn’t overly chunky. It all adds up, but the final number was still a pleasant surprise.

That result is almost five and a half feet better than our running average. In a word: wow.

I didn’t expect Tektro’s 2-piston brakes to land a score this strong. They’re reliably good, but upsizing the rotors and pairing them with the right setup clearly takes things to another level.

No notes here. It’s a fantastic brake performance and exactly what you want on a bike you’ll ride often, especially if you’re carrying a passenger.

We’ve been working our way through the AIMA catalog over the last few months and I’ve been consistently impressed. They get the fundamentals of bike design right and add thoughtful touches that make their models feel solid and comfortable in most situations you’ll encounter. The Big Sur U has a few limitations to consider, but the overall ride is well rounded.

The bike comes in a single frame size. I’d recommend it for riders up to about 6 feet tall or roughly a 32-inch inseam. I’m 6’1” with that same leg length and the ride is doable, but not ideal for longer legs. Leg extension is the biggest constraint; otherwise, the reach and handlebar height feel good.

The touch points are dialed. You get a soft saddle, BMX-style riser bars with ergonomic rubber grips, and sturdy alloy platform pedals to keep your feet planted. The rear passenger gets a cushioned seat, foot pegs, and mesh wheel guards to keep clothing clear of the spokes. If you prefer more cargo flexibility, you can remove the rear cushion and use the welded rack for other hauling duties thanks to its 45 kg weight rating.

I like that the saddle can drop low enough to sit nearly flush with the rear cushion. If you’re relying on the throttle and cruising around town, you can settle into a moped-style position that creates one long bench-like seating area.

AIMA includes an 80mm Zoom suspension fork. It’s entry level, but it smooths out bumps and potholes well enough for daily riding. When carrying a heavier load, I noticed it dives a bit in corners. It’s more of a quirk than a problem, and you can always lock it out for sharper handling at higher speeds.

The Big Sur U comes equipped with practical features: full fenders, a bright headlight, a brake light, and turn signals that beep to remind you to turn them off. I appreciate that since I often forget on silent systems.

The display is a highlight. It’s a large 4-inch TFT screen that’s easy to read and shows all the basics like speed, battery, assist level, and estimated range. It really comes to life when paired with the Bafang Go app. You can mirror call and text alerts on the screen, which is helpful if your phone is stashed away, though I wish it filtered out nonessential notifications instead of pushing everything through.

Navigation is another strong point. Enter your destination into the app and clear directional cues will appear on the display. For a utility bike meant to run errands or carry kids around town, that’s genuinely useful.

Handling is helped by the 20×3″ tires. The smaller diameter keeps the center of gravity low, which is especially important when riding with a passenger, and the extra width adds stability. The tread leans hybrid rather than knobby, giving you good efficiency without the noise or squirm of a chunkier tire.

AIMA also includes a dual-leg kickstand, which I love. If you’re loading a child on the back, having the bike sit upright instead of leaning makes the whole process easier and safer. A quick push forward collapses the stand as you ride away.

The frame feels solid overall. You get clean braided cables, an internal but removable battery, and sturdy construction for a step-thru design. For the record, I love the purple color. At the $2k price point I would have liked at least one alternative color option, but the Big Sur Sport 2.0’s silver frame isn’t as passenger friendly so this is the better choice for two-up riding.

Overall, the Big Sur U matches or exceeds the quality you’ll find on most comparable utility bikes. The value is strong for the price and the ride experience holds up well whether you’re solo or carrying a plus-one.

This isn’t the only Big Sur in AIMA’s lineup. If you want a full fat-tire experience, there’s a version with massive 26×4” rubber. If you prefer something more in the short-tail cargo or utility lane, the Sport model can be outfitted with whatever carriers or accessories you need. The Big Sur U, though, feels the most intentional. It was designed to be shared, and for that purpose AIMA did a great job equipping it with everything needed for tandem rides or solo trips around town.

The motor has plenty of power and the ability to fine-tune its personality through the app. Handling is stable and comfortable, and the safety package is extensive. The standout remains the braking performance, which ranks among the best we’ve ever recorded. It’s fun, practical, and confidence inspiring, which is exactly what you want for yourself and the person you’re bringing along.

The app meaningfully elevates the experience, and the styling works well if you’re into the bold purple finish. Aside from wishing for a slightly higher-end fork to better support heavier payloads, there’s very little to nitpick here. It’s a well-executed utility bike that delivers on its purpose and does so with personality.

AIMA sells via its dealership network which you can check out from the link above to find the nearest dealer to you.

Happy Riding! Make sure to let us know if you have any questions or if you think we left anything out in this review of the AIMA Big Sur U down in our comments section.