Electric

What makes an electric bike road legal in the UK?

An electrically assisted pedal cycle must have a motor rated at 250W or less, assistance that stops at 15.5mph (25km/h), pedals that drive the bike, and a rider aged 14 or over. A throttle that moves the bike without pedalling is only permitted up to 3.7mph as a walk-assist. Anything beyond those limits is legally a moped and needs registration, insurance and a helmet to motorcycle standard. Listings advertising higher wattage or a derestricted controller fall outside that framework, so read specifications carefully.

Hub motor or mid-drive — which is better?

Hub motors sit in the wheel, are cheaper, and are what most conversion kits use. They are simple and quiet but shift weight to one end of the bike and cannot use the gears, so they struggle on sustained steep climbs. Mid-drive units such as Bosch Performance Line, Shimano STEPS and Yamaha systems drive through the chainring, so they use the bike's gearing and climb far better, at the cost of chain and sprocket wear. Mid-drives also centre the weight, which is why most quality e-MTBs and cargo bikes use them.

Should I buy a complete e-bike or a conversion kit?

A conversion kit turns a bike you already own into an e-bike for less than a complete build, and suits a sound hybrid or city frame with rim or disc mounts to spare. The trade-offs are integration and resale: the battery usually straps to the frame or rack rather than sitting inside the down tube, the wiring is exposed, and the finished bike is harder to sell on. A complete bike gives you matched braking, a frame designed for the extra 8-10kg, and a manufacturer's battery. If the donor bike is worth less than the kit, buy complete.

What should I check on a used e-bike or battery?

The battery is most of the value and the thing that degrades. Ask for the charge cycle count — many Bosch and Shimano systems report this through the display or a dealer diagnostic — and treat 500 full cycles as the point where noticeable capacity loss sets in. Check the manufacture date on the cell pack, since lithium ages on the shelf whether ridden or not, and walk away from any pack with a swollen case, corroded contacts or a history of being stored flat. Then check the charging port pins for bending, the motor for bearing rumble or a rattle in the reduction gears, and the connector where the wiring loom enters the frame for chafe. On a mid-drive, look hard at chain and cassette wear — the motor accelerates it. Brake pads and rotors also wear faster on the extra weight.

What is a fair price for a used electric bike?

Value tracks battery health more than frame condition. A three-year-old e-bike with a healthy original battery is worth substantially more than the same bike with a tired one, because a replacement pack from a major system maker often runs to several hundred pounds — enough to make a cheap bike not worth reviving. Budget e-bikes with unbranded batteries and no replacement path depreciate hardest, so factor in whether cells are still obtainable. Buy new when you want a warranty on the battery and motor specifically. If an e-bike proves impractical, city bikes cover the same journeys without the electronics.