[fgfarben]

A heavy battery makes an ebike extremely unpleasant to pedal manually. You should try it.

I built almost exactly the same size pack (2 kWH) as Jacques in 2020 on a hybrid road bike and hated it so much that I only rode it 20 times or so. The battery still sits in the corner of my house doing nothing.

[lukan]

On a flat road I disagree, but uphill you notice it a lot of course, but way worse is carrying the heavy bike. I take mine into trains a lot and unfortunately there are often lots of stairs and no escalators involved.

[jacquesm]

I would never take this one into a train. I'm pretty sure it is a better pack (and much better monitored) than a store bought one given what I've seen inside of those but still, the amount of energy stored in there is pretty impressive and just the thought of it going into thermal runaway is enough to ensure that will never expose other people to it.

[lukan]

That is very considerate of you, but my bike has a very small standard battery (in comparison). Still, it would be good if trains offered a way to store the bikes in a special place away from people (at the end of the train for instance) so this won't be an issue.

[jacquesm]

Have a look at some videos of what it looks like when a pack lights off in an enclosed space. You'll come away equal parts impressed and horrified, especially at the speed and the intensity.

[lukan]

Will do that, but since I life in a mountainous area with only a rudimentary network of public transport, the alternative is taking the car.

[jacquesm]

Yes, that's a nasty spot to be in. I'm not sure how well this setup would work in more mountainous regions, here it is pretty flat except for the roads around Arnhem, especially the Gelderse Vallei where it feels - to my dutch legs anyway - pretty steep. But that's the only bit of hills that are worthy of the name, the rest is a flat as the proverbial pancake.

As for those videos: beware, there are also fake ones (there are about anything that gets clicks these days), but also many genuine ones. Not for the faint of heart.

[Panzer04]

It goes without saying that you need the electrical components to be operational and assisting, otherwise yes you are just hauling around weight for the sake of it. As the other commenter mentions though, on flat terrain this doesn't matter much (since wind resistance tends to make up most of the friction at speed, and is independent of weight)