January 3, 200719 yr Here is some information provided to me by the DfT: <snip> An electrically assisted bicycle: Under 40kg, with a 200w or lower continuous power output, and a maximum assisted speed of 15 mph is exempt from UK registration (and thus type approval) and is treated as a cycle. Note that "continuous power output". As I understand it, (mainly from Ben at Kinetics - thanks!) it's legal to have a motor that can output much higher power for a few minutes, so long as overall it can only average 200W. And that's useful for short steep hills. When looking at manufacturers' specs, they have an irritating tendency to quote wattage without stating if that's "continuous" or "peak". An added complication to an already complicated situation. Mary
January 3, 200719 yr Hi Mary, Think of the continuous power rating as the level above which, for the specified conditions, the motor becomes unable to dissipate heat faster than it's generated. So, the temperature of the motor rises, efficiency drops and eventually components start to degrade, unless there's a thermal cut-off. So the continuous rating is not an absolute or an average, strictly. Edited January 3, 200719 yr by Miles
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