Im planning to train,bus,cycle travel around northern Portugal and Spain.
Train, bus and cycle. That is something I would do with a Brompton folder. A Brompton isn't as comfortable as a large-wheel bike, but it saves a lot of hassle on public transport. I put mine in an opaque bag and treat it as any other luggage. That way I can use it combined with high-speed trains that don't have bike provision, coaches that refuse ordinary bikes, and even urban buses.
A Brompton can be electrified. But, for my own use, I prefer reducing the weight as much as possible so that the folded bike is easy to carry (on and off buses, up stairs in hotels). When I can no longer do long bike trips starting from home I plan to use buses and coaches more than I do now and cycle shorter distances, so a lightweight folder should make sense for me. My lightweight Brompton (equivalent P-Line) currently weighs a tad over 10 kg, with a few (rather expensive) modifications I reckon I can get the weight down to about 8.5 kg. Adding an electric kit would add about 3.5 kg, so that could be a possibility for train-assisted tours if I ever change my mind.
I have, however, started a projet to build up an electric bike using a bolt-on kit on an old ladies-style mountain bike. Ladies style in case I have problems getting my leg over a diamond frame, old steel frame for strength and durability. To start with, I plan on using it for towing heavy loads with my trailer, later on I will probably need to use it for other things. But only for trips I can do from home without using trains, because the problem with an electric bike is that a motor and battery suitable for towing a heavily laden trailer will add at least 5 kg. On a sturdy utility bike that means at least 22 kg even before counting luggage. I reckon that will be too much to manhandle onto a train when I am older and weaker.
It isn't the way I intend to go myself, but it is possible to have a lightweight electric bike. The British Cytronex company does kits to convert almost any bike to electric assist. These kits are only front-wheel drive and are relatively lightweight. They even say their battery can go on airline flights, but that would need confirmation, regulations sometimes change and would probably vary between airlines.
