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Around the place where I live the electric bicycle is gaining popularity and it's easy to pick those on such bike from far away not just from posture (rather stiff upper body even on steep hills) but also from their cadence: for some reason the majority (I'd estimate more than 90%) of the people I see on an ebike ride at a rather low cadence. It's hard to estimate how low but I'd say something like 30rpm; in any case: lower than any other cyclist on a normal bicycle no matter what type. So I've been wondering why and I cannot really figure it out (nor if they all do it for the same single reason). I don't really have the guts to just ride next to one and ask, also because I'm afraid to get frowning faces and answers like 'no idea'.

I was thinking it is maybe just as simple as 'because they can'. Maybe they all just think 'if it works ok spinning slowly, why spin faster'. But to me this is counterintuitive as even when I don't have to output a lot of power I'd still go for a decent cadence rather than a lower one as it just seems to work better and science seems to agree with me. And in any case I wouldn't go as low as they do. So I was thinking maybe they all were told to ride like that in the shop and/or there is some technical reason related to the whole drive system? Like it is more beneficial in terms of power usage or so? Or the bikes are just built with less gears and favouring the higher ratios?

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    In a word - "noobs" You'll also see them with saddles far too low, knees apart, and if they wear a helmet it may be tilted back on the crown of the head not on the forehead, or hanging directly from the bars. They'll also forget they're riding a legal road vehicle and may do Pedestrian-like things without warning. This isn't unique to e-bikes either. – Criggie Oct 24 '17 at 18:41
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    I'm not sure it's restricted to e-bikes either. Granted, I've not been out in the country lately to watch "real" cyclists go by, but I've seen lots and lots of riders who look the part slowly pushing big gears. – FreeMan Oct 24 '17 at 20:35
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    I ride a bunch of different bikes, and sometimes riding a big gear slowly is an awesome way to just cruise. Its not about Max Speed at all times. To people who would otherwise drive or walk, just being on a bike is an improvement. I've learned to not offer suggestions, just offer encouragements if the opportunity arises but it can scare them too, if they're used to the isolation of a car. In short - riding for transport is quite different to cycling for exercise. – Criggie Oct 25 '17 at 2:52
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    "science seems to agree with me"? Cadence is a product of how much power you can output, the chosen gear you're using, and how much speed you want to attain. I typically choose the highest gear I can use, then crank the cadence up to match the desired speed. My legs are much stronger than many of my friends who choose to use a higher cadence/lower torque combination. Add some details about what "science" you are relying on. – Max Vernon Oct 25 '17 at 15:51
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    Just a comment as I have very limited e-bike experience: I have the impression that "normal" e-bikes tend to have more metres of development (not sure about vocabulary here: I'm trying to translate Entfaltung) than "normal" non-e-bikes, i.e. they generally have higher gears / are missing lower gears ("you don't need them because you have the motor"). I've also read (possibly outdated by now: fahrradzukunft.de/9/elektrorad-selbstversuch) a testing report where the e-bike rapidly consumed the battery power uphill because the gears didn't allow slow going at high cadence in low gear. – cbeleites Oct 26 '17 at 12:33

10 Answers 10

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There are (at least) two reasons. First, most (but not all) E-bikes use a control system that multiplies the amount of force or torque that you put into the pedals or cranks. Since power is the product of pedal speed and pedal force (or torque), increasing the torque allows the rider to reduce the pedal speed -- that is, the rider's cadence. Electric motors (can) produce full torque at any rpm, so these controllers typically modulate the torque output rather than the rpm.

Second, if a rider on an E-bike were riding at "normal" cadence for his or her speed you would be less likely to notice the rider, so your observational sample is likely to be more heavily weighted to those with lower than normal cadence.

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    +1 Sampling bias can always be an issue when relying on anecdotal evidence. – Rider_X Oct 24 '17 at 16:20
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    Most e-bikes are cheap models, and most cheap models don't sense torque but have on/off switches for the pedal assistance (usually with a selector for how much assistance you want). I suspect it's got more to do with people not understanding or not caring – Chris H Oct 24 '17 at 17:04
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    2nd paragraph makes a fair point (could even be plain old confirmation bias though I doubt it) so now I'm really going to start counting. – stijn Oct 25 '17 at 8:41
  • @stijn you could get a dashcam and go over the footage after driving, if you're really curious. Then update us! – user34625 Oct 27 '17 at 21:31
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    @AytAyt don't have a dashcam, but started to look more carefully and noting down countings after riding. However one thing which is already bringing down my initial and faulty '90%' estimate is that the weather is becoming colder and more wet, which seems to lead to more noobs (assumingly) being filtered out, leaving more epxerienced riders. Which don't seem to opt for the extremely low cadences. – stijn Oct 28 '17 at 7:46
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In general studies have indicated that trained cyclists use pedaling frequencies higher than 90 rpm whereas untrained cyclists prefer frequencies around 60 rpm. I suspect the majority of e-bikers you encounter are not "trained" cyclists. Cycling co-opts a number of pathways we use for walking so people who are untrained typically cycle like they would walk, where a casual pace translates to a cadence of somewhere around 50-60 RPM.

That said, mechanically and metabolically a lower cadence may actually be optimal for e-bikes. The assistance provided by the motor means your physical effort tends to be less. Studies have shown lower cadences (i.e., < 90 RPM) can be energetically optimal for lower efforts and longer duration activities. Higher cadences tend to be associated with harder efforts, especially in trained cyclists. Furthermore, people also have a tendency to self select the most the energetically optimal cadences, especially for longer duration activities. For what they are doing, a slower cadence may be sensible.

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    +1 I have only briefly ridden an e-bike, but in my experience the optimal speed is at a slower cadence than a normal bicycle. If you try and push the speed above that, it feels like running through sand. I believe the motors have this intentionally built in, because my brother built his own ebike without such limitations and he can get moving really fast on his bike. – BlackThorn Oct 25 '17 at 15:28
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    @TBear I suspect the designers of e-bikes may have designed for a lower cadence as their target audience may be "non-cyclists." I have virtually no experience with e-bikes so this is rampant speculation. – Rider_X Oct 25 '17 at 16:15
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    OP is likely from Holland, given their name. Everyone is an experienced biker there. My daughter cycles everyday and she's four. Yet I see many people slowly pedaling. What's experienced? I think you mean that people experienced in biking fast, e.g., road biking or mountain biking, use high rpm. I road-bike a lot and low gears/high spin works best to keep on going at 30+ km/h. – AliceD Oct 26 '17 at 8:28
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    I think the second paragraph is spot-on. I've ridden an e-bike for a week, and in fact you don't need to increase the cadence that much since the motor helps you with torque. The main advantage is that you are far less likely to push too much and get to work sweated. – clabacchio Oct 26 '17 at 9:52
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    @AliceD - you are correct, my usage of "experienced" was implying performance training, I have updated the wording to "trained" to make the intent clearer. – Rider_X Oct 26 '17 at 16:27
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Personally it's because I'm using my ebike to get to work, wearing work clothes (which restrict my pedalling) and not wanting to get too sweaty. If I were just out for a ride I'd pedal faster.

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    That implies pedalling faster while putting less force on the pedals would make you hotter. I'm not really sure it does as the same amount of work is done, I think? – stijn Oct 25 '17 at 8:39
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    There is a constant friction force inside the body (muscles/tendons/joints), so moving body parts faster will increase heat generation because of that friction. – anatolyg Oct 25 '17 at 10:06
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    @anatolyg And you'd get more friction from your clothes cycling faster unless they were skin-tight. – SGR Oct 25 '17 at 10:46
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    @anatolyg thanks for sorting that out. I guess that's what I get for not actively using/thinking about any physics theories for more than a decade: lack of 'physics mindset' – stijn Oct 26 '17 at 7:30
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For me, as an occassional ebike rider, it feels I get kind of better connection to the bike when pedaling at lower cadence, but higher force.

Because the electric assist otherwise reduces the needed force, it can feel like eternal downhill and it gets harder to sense your speed. But when I switch to higher gear so that I need to push harder on the pedals for a given power output it feels more like normal biking. I tend to do the same when going downhill on a regular bike also, even though I could as easily just not pedal at all.

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It could be that all they are doing is rotating the pedals - not because they have to input any force to make the bike go but because the motor will not run with receiving a continuous signal from a hall-effect switch coupled to the pedals.

Thus the motor is enough to move the rider alone, but unless the rider is also rotating the pedals a cadence sensor as "safety feature", legislated in some areas, will detect that the rider is no longer rotating the pedals and will cut off the motor.

This is not a torque sensor, a much more expensive device.

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    There are also a lot of e-bikes (admittedly higher end) that force sensors rather than cadence, so as to multiply the the riders input rather than do all the work for them. Here riders have to contribute a bigger effort to go faster (rather than to just turn the pedals). E-bike" is a wide banner of systems. – Rider_X Oct 26 '17 at 21:43
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I tested ebike today. I'm used to full-carbon race bike and ride daily for commute + hobby. i'm used to ride at 90+ RPM and i'm very happy with this cadence.

2 ebike : an low-end urban ebike, a mid/high-range mountain bike.

I tested the urban ebike first at my usual RPM. a few later after startup i was at 30+km/h (huh?), way above the 25km/h assist limit. i mostly wanted to play with how it handle at low assist, for endurance purpose.

Then i played with the MTB in "i'm super lazy mode" with the ridiculously high torque of the bosh performance CX.

It turn out immediately dropped my RPM to less than 60.

Simply because pedalling at high speed, even with 0 resistance (eg : freewheel or descent) IS work. 90+ is work for moderately trained cyclist, and impossible to untrained people sitting in front of a computer all day long. (i know i couldn't do it, 75rpm was my bested painful maximum for some time).

we ride at 90+ because it's more efficient to have high-speed low-torque than the opposite. And if you care aboute aerodynamic it's even more difficult to put high torque in crouched position.

But with ebike, you don't care about your muscle torque and don't care about efficiency if you just commute 10km on a bike that have 80+km battery. So.. max assist, no leg work, and not a care in the world about sucking up your battery at crazy rate.

Therefore : low rpm = less work (as long as you don't care about torque, which is the case on ebike at max assist)

offtopic PS : my tiny experience shown that the lowest assist mode on a heavy eMTB is pretty much the same thing as riding a lightweight carbon race bike. (on flat road, i didn't have any hill close enough)

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The riders are pedaling only for the electric motor to kick in, not for creating leg power. For this they pedal as slow as they possibly can.

The main reason for the bike to work this way is a legislative one: it is a "power assist" bike not a scooter. Effectively most ppl use it as a scooter, some even install a throttle handle to override the pedaling mechanism.

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    Thanks for contributing but really, this is one of the two main reasons why new users aren't allowed to post comments. "This answer is right" comments aren't helpful -- that's what voting is for. "This answer is right" answers takes up even more space on the page and aren't even closely linked to the answer they're talking about. (The other reason new users can't comment is to avoid spam, but that's obviously not relevant, here.) – David Richerby Oct 26 '17 at 10:41
  • Well, after reading all answers, I'm more and more thinking there is not going to be just one single definitive answer. Not only because it seems there are multiple types of drive systems/sensors/... but also different type of cyclists, I think not all people do it for the same reason. In other words: while e.g. Adam's makes complete sense for that particular type of bike it is, as far as I know, not the single answer applying to all cyclists I see. – stijn Oct 26 '17 at 10:42
  • Welcome to Bicycles SE. It only takes 15 reputation to upvote an answer. Once you've asked and answered a couple of questions, you'll have that privilege. In the meantime, I'd recommend deleting this answer so that it doesn't continue to attract downvotes. – jimchristie Oct 26 '17 at 18:02
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Most people that I see on e-bikes are not 22 year old athletes wearing a yellow shirt. They're 45-75 years olds and just want to move their legs a bit (but not too much, to be honest) and be out in nature.
Or, as it happens, they're bankers in suits cycling to Bankfurt, which except during the heaviest rain and hailstorms seems to be a lot more appealing than driving with a car, given the traffic and parking situation.

A not-e-bike allows you to cycle with low cadence, too (assuming a bike with gear shift, which is de facto "normal").
But why don't people do that? Well because of the lever principle, and because of the power formula. You can gain the same speed by treading harder but slower, or by treading faster and more comfortably. Similar for power, you can just interchange speed and force (torque in this case). Tread harder or faster, same thing. Absolutely no difference.

So there's no real reason? Yes, except...

Except muscles don't care about your pretty laws of physics. Muscles don't like going out of their comfort zone too much. They will rapidly tell you by generating pain instead of power (pain persisting for days if you do it too long), and outside their comfort zone power output will overall be a lot worse. Incidentially, many machines (e.g. combustion motors) do not behave a lot differently. Electric motors are really a super rare exception because they operate in "don't care" mode at virtually every speed, and with ridiculously high torque all through.

Higher cadence means not only better (much better) power efficiency, but more importantly there's less torque (i.e. less muscle force) needed, which means more comfort, less pain and sweat, less "sheesh, I'm going to die", and less inability to walk during the next two days.

That's why you cycle at 60-70 rpm (or 90+ if you are young or sportive) rather than 15-30 rpm with a conventional bike.

With an e-bike, you can as well tread slower, which is less exertive. Let the electric motor help a little, why not (that's why you bought it). You do not even need to breathe noticeably faster. Which is nice if you like having a conversation with your partner.

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    Note 'higher cadence -> less sweat' is the opposite of Rupert's answer – stijn Oct 28 '17 at 12:58
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    @stijn: Yes, and either claim is correct... within its bounds. With identical torque, lower cadence is less excerting, and thus translates to less sweat (pretty obvious, less power output!). Gears on a traditional bike allow you to exchange higher cadence for lower torque to the same net effect, which is within some bounds considerably less excerting, though at some point, this turns around. The trick with an e-bike is, however, that you can have lower cadence and the same or lower torque at the same time (because the motor delivers some, too). Thus slower is less excerting. – Damon Oct 29 '17 at 14:27
  • @Damon: The sweat is produced to cool the body, so it's a measure of your body temperature not of your level of effort, nor (at a similar level of effort) of your cadence/force/... – Calin Ceteras Mar 21 at 9:14
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One aspect not mentioned yet: With normal bikes cadence increases with speed in order to limit the force needed to sustain the speed. The wind resistance which must be overcome grows quickly with the speed, and e-bikers typically travel at speeds which would force an unassisted cyclist to increase their cadence because the force they can sustain has hit a ceiling. (This is the reason why a car typically does not reach its maximum speed in the highest gear -- too much force/torque needed.) With an e-bike the force comes from the motor, so a more comfortable and economical lower cadence can be maintained. Conventional biking at e-biking speeds at a low cadence would be hard on the muscles and knees.

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High cadence is maximizing power output for trained bicyclists. Why would those be riding an E-bike?

A similar divergence is that high cadence, particularly when combined with sweat, stresses trouser legs which will get bulgy a lot sooner (and the seat area is also getting additional stress). That's one reason trained bicyclists prefer wearing biking clothes and having the work clothes stowed at work or in sidebags.

I went through a whole lot more trousers when using jeans rather than biking clothes everywhere. E-bike users tend not to wear special clothing: getting all sweaty is not what the bike is supposed to be for: rather you use it to arrive in presentable shape without significant adjustments.

A basic point of using an E-bike is putting less energy in yourself than you need for biking. Theoretically, you could just use it to buffer energy for the worst passages, but in practice they are charged externally.

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    "getting all sweaty is not what the bike is supposed to be for" - I think the purpose of an ebike should be for whatever the rider feels appropriate. Some may use it to make it long distance commutes more attainable, or have a shorter transit time (i.e., faster speed), while others may wish to arrive without sweating. I don't think we can argue for a single defining purpose. – Rider_X Oct 26 '17 at 21:54

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