Compact bikes that fold for apartments, RVs, trains and car trunks.
A folding e-bike trades a little ride quality for the ability to collapse into a car trunk, an RV bay, a closet or the corner of a small apartment. The frame hinges at the middle, the stem folds down, and most models fold pedals too, bringing a full-size ride down to a package roughly the size of a large suitcase. That makes them the default choice for people who cannot leave a bike locked outside and for anyone combining a bike with a car, train or boat.
Be honest about weight before you buy. Many folding e-bikes, especially 20 inch fat tire models, weigh 60 to 75 pounds — they fold, but you are not casually carrying one up three flights. Lighter folders with 16 or 20 inch narrow tires, smaller motors and 36V batteries can land in the 35 to 50 pound range and are realistic to lift into a trunk. Decide whether you need the bike to be carryable or just compact; those are different products.
Ride quality depends heavily on wheel size and hinge quality. Small wheels accelerate quickly and are nimble but react more to potholes, and a flexy hinge makes the whole bike feel vague at speed. Look for a latch with a secondary safety catch, an adjustable-height stem so the fit is not a compromise, and a rack and fenders that fold with the bike. Brakes and battery rules are the same as any e-bike: hydraulic discs are nicer, and a 48V pack around 500Wh gives usable range. Owners whose folder has developed a rattle, a loose hinge or an electrical fault should get an E-Bike Assessment rather than ride it and hope.