We plan to ride across Europe next Summer, family of 4 including two girls (6 and 11). We have no doubt that our 11 yo will pedal her way. But our 6 yo will need help.

At first we thought that a tag along would be best. But now I wonder if an e-bike might be a better solution.

Googling e-bike for kids returns toys that have nothing in common with what we would consider.

I don't know if a retrofit kit can be installed on a tiny frame, nor if a 6 yo can handle such contraption.

What are your thoughts?

I might not be the best person to answer because I have no E-bike experience. My first reaction is that a child with iffy riding ability wouldn't be a good candidate for using an E-bike.

Sounds like the vacation from hell for the kids, and I'd bet they never cycle again.

Anyway, are you expecting the 6 y/o to ride his own bike for thousands of miles across Europe? Are you serious, or trolling?

And e-bikes have a short range, then they have to be recharged, or they are just dead weight. Are you going to carry the bike up to every hotel room and pack the charger too?

I suggest you rethink your plans. A trail-a-bike would be better. A train ticket would be best.

I agree that the E-bike is a very poor idea for a 6-year old and not much better for anyone else on tour either. They have a very short range, have to be recharged often, are heavy and can be dangerously fast for any small child to be expected to control properly.

A tag-along is a possibility but a true tandem with a kid-back crank (or Co-Motion's "PeriScope" with it wide range of stoker seat adjustability) is an expensive but far better idea.

BTW, what do the kids think of this idea? Are they looking forward to it or dreading it?

Bionx makes a retrofit kit with range in excess of 100km. That would be plenty.

Not clear at all that a young child can ride this properly however. We can always have a speed limiter, but there are 8kg that could make the bike iffy to handle. So yes, a tag along appears to be better. (followMe allows the child to ride alone if s/he wants, and eventually be trailed by an adult. Important for the child to feel independent)

As far as the kids are concerned, they are looking forward to next Summer. This past, we hiked more than 1500 kms (25+ per day). Our little one was riding a donkey. Our 10 yo walked all the way. Next Summer should be different but rewarding. Hell yes

Sounds like a bad idea to me, and I usually like doing stupid things.

If you get pedal assist, then it should work like a regular bike, but just a bit easier. I don't see why a kid couldn't learn to ride it. And, there are a few E-Bike kits that could be adapted to smaller bikes.

Perhaps make the battery easily removable, so you can carry a spare in your luggage, and take it off the bike if you wish to ride without assist.

However, I'd encourage you to look at tandems. Something like a Bike Friday tandem can be disassembled for shipping, and can grow with the family.
https://www.bikefriday.com/bicycles/tandem

Or, something like the Kidz Tandem would allow you to interact with the kid a bit more, so it would also have benefits.
Brown Cycles of Grand Junction, Colorado