E-bike energy use

Now that I’m seeing e-bikes everywhere, particularly for non-recreational purposes, I have a question, knowing little about them. In general, and I’m sure there’s tons of variability, how much of the energy for a typical e-bike ride comes from the rider vs. the battery? I’m wondering if the assist is just a little extra to save riders from hard efforts, or is it more like a motor-bike with a pedal assist when riders want to feel like they’re participating?

As I said, I’m sure there’s a wide range of answers here. I guess I’m curious what’s most common.

The short answer is “it depends”. Want to take a mtb up a long and technical climb? Getting up there in age and want a small assist so you can still hang with younger friends? Have a spouse that kicks your ass but want to go for a fast ride together? You’re gonna work your butt off. Those kind of bikes have settings that give you a little pedal assist so you can ride harder, faster, and farther.

Want a bike with a throttle? Well, I think the fact the bike has a throttle answers that question.

Both have their place, and in my opinion, it’s wonderful that more and more people are using bicycles to get around, even if they’re just running errands or going for coffee and not “working out”.

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My wife and I bought a commuter/cargoish ebike. We live at the top of a hill and while the flats are fine with groceries, the big hill can be a killer when fully loaded.

Occasionally, one of us will use it to slipstream tow the other at 20-28mph (class 3 FTW!). My wife is excellent at turning up the speed up a hill at just the right amount to make my eyes bleed. We don’t really do dedicated rides for that, there’s generally groceries along for it. Multitasking!

I’ve been known to cruise in to work on it the day after a weeknight race that left me shattered.


E Bike power can ususally be configured from a small to large power addition.

My wife has a Specialized Vado SL and has the power adjust set to 50% addition on flattish terrain but switches to 100% or 150% on hills.

i e. If the rider is pushing 100W the motor adds 50W, 100W, 150W respectively.

So the rider can configure the type of assist they want and can based on what power they can output.

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Sorry, this is another “it depends” response. My wife rides an Orbea ebike , she’s late 60s, arthritis, but a long term bike day tourer… the bike is at the lighter (& less watts) end of the scale. But the benefit for her is the actual availability of the power. Typically she’ll ride 40k without motor, and only use it on long hills, or when she tires. The availability of the motor gives her the confidence to ride further, or more challenging rides.


Depends on the type of bike (as already said, bike with assist - that works only if you pedal vs bike with a throttle).
It also depends where you are. in Europe:

  • Regular ebikes assist stops at 27 km/h. So on the flat it’s not helping a lot unless you are completely unfit or limited by age / disease (or handicap) / both. It’s mostly a uphill boost.
  • Speed bikes (with assist over 27 km/h) are considered as mopeds so require a stronger helmet, insurance and a licence plate.

In the US (OZ / NZ I don’t know) the limit is 20 mph so a recreational bike can give a significant boost (20 mph on a false flat in a headwind require serious fitness).

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Sure of the 27km/h limit? As far as I know in Italy the limit is 25km/h and this should be the same for all EU.
No need to say that EVERYONE that buys an e-bike, here in Italy, do the illegal modification to remove the limit and use it as a moped without insurance, helmet… or to outpace fit amateurs on road bikes during the group ride (but still thinking of doing an actual workout)…
Persons to be avoided…

You are right, officially it’s 25.
But I gathered that it was actually 26 because 25 and something are considered 25. As the power doesn’t immediately cuts off at 26 (maybe depending on bike models), you actually are helped up to 27 roughly.