http
/en.wikipedia.org/wiki/Electric_bicycle_laws
In the United States of America by Federal Law electric bikes are limited to
a maximum electric assist motor speed of 20 mph which is around 32 kph and the top wattage of around 750 watts for the motor rating.State laws vary however as in my particular state (Washington State) 1000 watt motor ratings are allowed to remain legal (say for just an electric motor kit probably not a electric bike as it would be likely under federal laws(750 watts max) to be sold in other states ).
These will become especially popular/nessessary as alternative transportation when petroleum fuels worldwide become depleted/exhorbitantly expensive in the near future like a couple of decades from now.Also electrical energy will become scarce and highly expensive as well since climate change will be devastating to hydoelectric sources (lack of glacial melt to feed them).
.Basically forget electrical energy eating hog electric cars as an alternative in the future in several decades from now unless you will become wealthy enough to afford either them or the immense cost of electricity by then.Replacing fossil fuel large vehicles in their present numbers with electric large vehicles (like passenger cars and trucks) won't be practical because there won't be the electricity worldwide to power them.
The worldwide adoption of high power efficiency (like 900 MPGe to 1,800 MPGe) electric bicycles would however likely be practical.Also they are are more limited in range so the overall power usage would be far less than any electric car.
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