Best 20-inch folding fat tire bikes under $400

Top pick: Aostirmotor 20" Folding Fat Tire e-bike (500W, 36V 13Ah) — it's the only one here that ticks all three boxes: true 20-inch wheels, a folding frame and real fat tires, with a 4.4-star rating from 31 owners and UL2849 certification. A 500W motor and 20 mph top speed make it a solid errand-and-campsite runabout.

Who the others suit:

• Vivi 20" x 2.4 Folding — the crowd favourite (4.5 stars, 226 ratings) and punchier with a 1000W peak motor, but its tires are wide, not fat.
• URLIFE 20" Fat Tire — fat tires and 20-inch wheels, but the frame doesn't fold, so it's for riders who don't need to pack it down.
• ASKGO 750W Foldable — most motor for the money and it folds, but the wheels aren't 20-inch and the tires aren't fat; the 3.5-star rating is a caution.
• Leavan Aostirmotor Folding — folds and has a 500W motor, but no fat tires and only one rating so far.

If fat tires and folding are both must-haves, the Aostirmotor is the one to get.