Vivi ACE07 750W Fat-Tire Step-Through

The 30-second verdict

Vivi's top-of-catalog bike, and a meaningful step up from the C26UL cruiser: 750W rated rear hub (Vivi claims 1500W peak), a 720 Wh battery that's actually large enough for daily commuting, hydraulic-ready 180mm disc brakes, a front suspension fork, and a step-through frame with 26x4.0 fat tires. The combination of fat-tire flotation, 720 Wh battery, and step-through ergonomics is rare at the $799-999 price — the Cyrusher Kommoda 3 is the obvious comparison and the closest sibling in our catalog.

What you're trading: this is still a Class 2 bike (20 mph cap), still cadence-sensor pedal assist (Vivi hasn't moved to torque sensors), and the 75 lb weight means moving it without the motor is a workout. If you want pavement speed (28 mph Class 3) or torque-sensor smoothness, you're shopping a different bracket entirely (Heybike Hauler, Lectric XPedition, etc.).

Power and battery

750W rated hub with 80 Nm torque is the right number for a 75 lb bike with fat tires — fat tires have much higher rolling resistance than 2.5" street tires, and the extra motor power compensates. Vivi's 1500W peak marketing figure is a brief burst, not sustained output; the 20 mph Class 2 cap still applies. The motor pulls a 200 lb rider up a 7% grade in PAS 5 without obvious strain — better than the Vivi 26" Folding (500W) and approaching the Heybike Hauler tier (1000W rated).

The 48V × 15Ah = 720 Wh battery is the load-bearing spec. That puts the ACE07 in the same battery class as the Heybike Cityscape 2.0 and Cyrusher Kommoda 3 — meaningfully larger than the typical 374-470 Wh budget e-bike. Vivi claims 40-55 mi range; real-world fat-tire commuter riding (PAS 3, 170-lb rider, mixed paved + light gravel, some throttle) lands at 30-40 mi. Snow + cold weather drops that to ~25 mi. The battery is removable for indoor charging — meaningful at this weight (you do not want to wheel a 75 lb fat-tire bike into a third-floor apartment).

Fat tires — where they help and where they don't

Fat tires (26x4.0) earn their keep on: snow (the only e-bike tire that actually works on packed snow without studs), sand (beach commuting becomes a real option), gravel and unsealed roads, and very rough urban pavement (potholes, sunken sewer plates, eroded curbs). The flotation is real.

Fat tires actively hurt on: smooth pavement (high rolling resistance — you lose 20-30% range and the motor works harder than a comparable 2.5" tire), tight cornering (fat tires want to stand the bike up — they push outward in fast corners), and weight (a fat-tire wheelset is 4-5 lb heavier than a comparable 2.5" wheelset). If your commute is 100% paved roads in a temperate city, you don't need fat tires — buy the C26UL or a Heybike Cityscape 2.0 and save the weight.

UL 2849 certification — the real reason to consider it over no-name fat-tire bikes

Vivi's ACE07 carries SGS-issued UL 2849 certification for the entire electrical system. Most cheap Amazon fat-tire bikes (Ancheer, ECOTRIC, no-name imports) do not — and the fire-risk profile of a high-capacity (720 Wh) battery on an uncertified electrical system is the worst-case scenario for the post-2023 NYC fire incidents that drove NYC Local Law 39 and California SB 1271.

If you store your e-bike indoors (apartment, garage attached to living space, shared workspace), UL 2849 is the safety floor — and the ACE07 is one of very few sub-$1,000 fat-tire bikes that has it. The Cyrusher Kommoda 3 does too, and is the natural comparison.

Build, brakes, frame

180mm hydraulic-ready disc brakes front and rear — hydraulic on the version Vivi currently ships per the Amazon listing, mechanical on older variants. Verify the version before ordering if hydraulic matters. The brakes are appropriately sized for the bike's mass — fat tires + 75 lb of bike + 200 lb of rider needs every bit of stopping power, and Vivi has spec'd accordingly.

Front suspension fork is a basic spring fork — present, not adjustable. Adequate for the bike's intended use (fat tires absorb most of the small bumps anyway). The 7-speed Shimano drivetrain is the same generic Tourney-tier groupset that's on most Amazon e-bikes at this price — replaceable, serviceable at any bike shop. Step-through frame with a low ~16" top-tube clearance, comfortable for riders 5'2" – 6'3". Rear rack and full fenders standard. Front + rear lights wired through the battery.

Who should buy it

Buy this if you commute in snow, sand, or rough gravel (the fat tires + 720 Wh battery + step-through is the right combo), if you want a UL 2849-certified fat-tire bike under $1,000 (rare combination — the Cyrusher Kommoda 3 is the only other obvious answer in our catalog), or if you want the most utility-shaped Vivi (true step-through, big battery, rear rack standard). Skip this if your commute is 100% smooth paved (fat tires cost you range and add weight without benefit — buy the C26UL or a Cityscape 2.0 instead), if you need Class 3 speed (28 mph — Vivi caps at 20 mph), if you can't store a 75 lb bike conveniently (it's heavy enough that the carry-in-out logistics matter), or if you want torque-sensor smoothness (Vivi is cadence-sensor across the catalog).