Vivi ACE07 750W Fat-Tire Step-Through

750W rated hub with 80 Nm torque on the listing we first reviewed (the current Amazon listing states 90 Nm; Vivi has published both figures) is a sensible spec for a 75 lb bike with fat tires, which have much higher rolling resistance than 2.5" street tires. Vivi's 1500W peak marketing figure is a brief burst, not sustained output; the 20 mph Class 2 cap still applies. It is a stronger motor on paper than the 500W Vivi 26" Folding, but we have not ridden it and cannot tell you how it climbs.

The 48V × 15Ah = 720 Wh battery is the load-bearing spec. That is meaningfully larger than the typical 374-470 Wh budget e-bike (the Heybike Cityscape 2.0 carries 468 Wh), though smaller than the Cyrusher Kommoda 3's 960 Wh. Vivi claims 40-55 mi range; our planning estimate, not a measurement, for fat-tire commuter riding (PAS 3, a 170-lb rider, mixed paved + light gravel, some throttle) is 30-40 mi, and snow plus cold weather could cut that to ~25 mi. The battery is removable for indoor charging, which matters at this weight (you do not want to wheel a 75 lb fat-tire bike into a third-floor apartment).

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, so 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, pushing 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.

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 a small number of sub-$1,000 fat-tire bikes that states it (Vivi lists it on the ACE01 and F26FUL too). The dearer Cyrusher Kommoda 3 is the natural step-through comparison.

180mm disc brakes front and rear: hydraulic on the version the Amazon listing described in May 2026 (that listing has since been replaced), mechanical on older variants. Verify the version before ordering if hydraulic matters. The brakes are appropriately sized for the bike's mass, because fat tires + 75 lb of bike + a rider need every bit of stopping power.

Front suspension fork is a basic spring fork, present but 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 and 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.

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 step-through under $1,000 (an uncommon combination), 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, so buy the C26UL or a Cityscape 2.0 instead), if you need Class 3 speed (28 mph, where 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 a torque sensor (the ACE07 is cadence-sensor; the high-step Vivi ACE01 lists a torque sensor).