Hi.
I was thinking of putting a motorbike on the back of my Kontiki however i was worried about the weight, not to mention the cost. A friend suggested an electric bike as an alternative as they are lighter, cost less (?)and I believed that they are not hampered by the restricive lesgislation concerning tax, insurance, helmet etc. (in the UK at least). However.. a friend tells me that there is a limit to the battery power output allowed here. Is this true and if so what is the limit?

As I understand it, the UK limit which is measured in 'watts' for a battery powered bicycle is 200 watts, which is only half a horsepower. (although I believe bikes with battery power of 1000 watts are available) Anything more powerful than that would classify the bike as a 'motorcycle', with all the legal implications that would suggest. I.E. Licence, tax, insurance, etc,etc.etc.
So if you do go to buy one ask the dealer or private seller for it's power rating and make sure that it is 200 watts or less, and also make sure that the batteries are of the Lithium Polymer type for longer range.
I am not sure what the rules are in other parts of Europe so best check before you go.
On the issue of price, you can pay anything from £199 to over £700 for a new one.

As well as the 200W limit, to be able to ride an electric bike on UK roads without number plates, insurance etc etc it also needs to be capable of no more than 15mph and must weigh less than 40kg (60kgs for tricycles and tandems).

There is a very useful article here that might help: www.whycycle.co.uk/bike_styles/electric_bikes/