The position is this.
Nominal power: EU 250 watts, UK 200 watts bike, 250 watts trike.
Pedelec: EU compulsory, UK optional.
Throttle: EU only combined with pedelec, UK throttle only permitted.
Assisted speed limit: EU 25 kph with gradual power phase down leading up to it, UK 15 mph with no phase down necessary.
Maximum weight: All areas: 40 kg bike, 60 kg trike or tandem.
Lower age limit: Only Sweden (15 years) and Britain (14 years).
Some countries have additional laws. For example, Germany has an over-riding 24 kph limit, and Sweden requires third party insurance and helmet wearing but allows 30 kph (18.75 mph). Germany and outside the EU, Switzerland, have high speed e-bike classes in addition, permitting around 20 mph but with other restrictions like insurance and helmet wearing.
In this country we have both laws fully in force and conflicting due to the civil service error in failing to arrange cessation of the UK law. Theoretically it would be safest to only stick to one set of rules and not "pick and mix", though the risk of any police officer having a clue about e-bike law is vanishingly small.
The Department for Transport have refused to give a definitive ruling while both laws are in force, saying that only a test case before the courts can resolve a prosecution outcome.
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