Folding e-bikes
A folding e-bike folds down to a size that goes through the door and into the boot, and it pairs well with the train. In the European Union only a machine up to 250 W and 25 km/h counts as a bicycle, stronger models are for private land or need registration and insurance. The folding hinge is checked before every ride, because a latch that opens on the move throws the rider to the ground. Work the real range out from watt hours, not from the number in the listing.
Folding e-bikes
A folding e-bike folds down to a size that fits the boot, the train and the stairwell. The category runs from city twenty-inch models with a motor up to 250 W to off-road machines on fat 20 by 4.0 inch tyres with two batteries. The difference between them is not only the kit, but above all where you are allowed to ride them at all. Weight runs from around twenty kilos on the city models to thirty-five on fatbikes, so a folded bike is something you roll rather than carry up the stairs.
In the European Union only a machine up to 250 W and 25 km/h counts as a bicycle, one where the motor helps only while you pedal and cuts out above twenty-five. A model with 500 W and 32 km/h, let alone a machine with 2000 W, is no longer a bicycle, so it has no place on the cycle path and none on the road without registration, insurance and a licence. Buy the stronger models, therefore, as machines for private land, a closed site or ground with the owner's permission. What counts is the continuous rated power on the motor plate and the rules of the country you ride in, not what the listing says.
The most heavily loaded point is the folding hinge on the frame, and the second one sits on the stem. Before every ride check that the latch lever has seated against its stop and the safety catch has clicked in, because a hinge that opens on the move throws the rider to the ground. The hinge bolts are tightened with a torque wrench to the manufacturer's figure, not by feel, and checked again after the first hundred kilometres. Compare the folded dimensions with your boot before you order the bike, on fatbikes the fat tyres are often more of an obstacle than the frame.
The range figure is measured at the lowest assist level, on the flat and with a light rider, so work the real number out from watt hours. A battery of 36 V and 14.5 Ah holds 522 Wh, the pair of 48 V and 20 Ah holds 1920 Wh together. A folding e-bike uses roughly 10 to 15 Wh per kilometre in town and 15 to 25 Wh off road on fat tyres. That comes to about 35 to 50 kilometres on the smaller battery and 75 to 130 kilometres on the pair of large ones.
Small twenty-inch wheels and over thirty kilos of weight ask more of the brakes than on an ordinary bike. Hydraulic disc brakes take repeated braking from thirty better than mechanical ones, where the cable stretches over time. Keep the pressure in fat tyres low for grip, but never below the value moulded into the sidewall, or the tyre rolls off the rim in a corner.