Wednesday, 12 September 2018

Riding e-bikes does not lead to health benefits

A recent study ("Transport mode choice and body mass index: Cross-sectional and longitudinal evidence from a European-wide study" by Evi Dons and others) compared the effect of different modes of transport on the BMI of thousands of European commuters. Each participant provided details of their height, weight and age as well as their mode of transport, followed by a second survey 18 months later asking the same questions. The effect of different modes of transport on BMI could therefore be compared and the effect on body weight due to daily exercise related to mode of transport was ranked:
  1. Riders of normal bicycles, powered by human muscles alone. These participants had the best score, achieving relatively low BMI.
  2. Pedestrians were in second place. Walking is beneficial for the body, but walked journeys tend to be extremely short due to the time taken to cover distance so this limits the overall benefit.
  3. Users of public transport came in third. Almost all users of public transport get exercise walking to bus stops or train stations.
  4. Motor cyclists score similarly to people who use public transport.
  5. Riders of e-bikes came in second to last.
  6. Drivers of cars took the last place, with the highest BMI.
E-bike parked on the street in Assen. Note that the top gear is
selected. Almost all parked e-bikes are the same. Users select
top gear and maximum assistance from the motor, resulting
in so little effort possible being required from the rider.
It was noted by the researchers that walking or running even to a bus stop burns more calories than hopping onto a bike with a motor immediately outside the door. This is why even travelling on public transport gave more exercise than an e-bike.

Participants who swapped from driving to cycling during the study lost weight. For men, this weight was loss averaged 0.75 kg while women lost a little less.  On the other hand, the BMI outcome for e-bike riders, motorcyclists and car drivers in this study is extremely close. Using a motorised mode of transport does not give a health benefit.

Conclusion
E-bikes can genuinely be of assistance for people who are less active due to age or health problems as they allow those people to remain more mobile than might be the case without a motor, but it shouldn't be a surprise that the health benefits of cycling disappear if you fit a motor to a bicycle. The exercise benefits of pedalling are lost when you're no longer pushing the pedals hard.

If you're a healthy and able human then an e-bike is as bad for your health as any other motorized vehicle such as a motorbike or a car. We each need to exercise on the order of 30 minutes a day just to get enough exercise to remain healthy. On a human powered bicycle that equates to riding around 5000 km a year.

Update 13 September
This blog post does nothing but report on the study linked at the top. The scope of the study was changes in BMI due to using different modes of transport and the resulting personal health benefits, if any, which resulted. A few people have responded by telling me that they exercise while riding their e-bike. That's great but it has nothing much to do with the study. Neither the study authors or myself ever claimed that it was impossible to exercise while riding an e-bike.  This relatively long term study suggests that, on average when considering thousands of people's behaviour, those who choose an e-bike to make their journeys do not get significant exercise while those who ride human powered bicycles do get significant exercise.

Other effects such as local air pollution or CO2 footprint of different modes of transport are beyond the scope of the study.

Several people have criticized my use of the term "health benefits" in the title of this piece as if this didn't come from the study itself. In fact, it was taken directly from the conclusion at the end of the abstract: "Conclusions: Our analyses showed that people lower their BMI when starting or increasing cycling, demonstrating the health benefits of active mobility." It's quite clear that being active is the key. Also note that "cycling" in this case refers to human powered bicycles. The same health benefit was not found for riding an e-bike and the inference is that many people who ride e-bikes are significantly less active than those who ride normal bicycles.

The type of e-bike which the study refers to is a 25 km/h maximum assisted speed pedelec. Anything else is not a legal e-bike and would fall outside the scope of the study. You have to turn the pedals to make the assistance work on these, but you don't necessarily have to push the pedals very hard so it is possible to select top gear and do the minimum of work.

Average speeds of Dutch cyclists. There's not much of a
workout to be had even on an unassisted bike at 12 km/h.
You get less exercise if going barely faster with a motor.
Source: Mobiliteitsbeeld 2017 / KiM
Why does rider health not always benefit from riding an e-bike?
We can only speculate on this subject because there is no data. I suggest that it comes down to habit as much as anything else. In the past people have suggested changes of behaviour such as that drivers of cars could improve their health by, for example, parking their cars one km from work and running the last kilometre. A few people might do things like this, but the majority of car commuters drive all the way to their place of work as that is most convenient for them. I suggest a similar situation arises with e-bike riders: i.e. many could well begin with the intention of pushing the pedals harder, but they slowly find that it makes little difference to their journey time whether they work hard or let the battery do the work so it's easy to fall into doing less.

There are many e-bikes in the Netherlands and it is clear from watching how people ride these bikes that very many riders take the option of riding with an extremely low cadence in top gear and letting the motor take the strain. That the speeds of e-bikes are barely greater than the speeds of unassisted bikes supports this argument.

E-bikes for children ?
Dutch children have historically scored well for low obesity and good well-being in comparison with children from other nations. This comes in no small part due to the exercise of everyday cycling, to school and back, to visit friends and for other purposes. School children are increasingly using e-bikes are increasingly being given to school children, and manufacturers have been happy to push this demand, providing lower cost e-bikes for children (from €1200) and some manufacturers have gone as far as to suggest that the majority of children will have electric bikes within a few years. A child who is barely pushing the pedals will not get as much exercise as his classmates who provide all their own energy. I am not the first person to note that the relatively good fitness of Dutch people could be undermined by e-bikes.

Am I some kind of anti e-bike monster ?
Some of the more bizarre responses which I've received have suggested that I'm either part of the car lobby or that I'm part of the bicycle lobby. Neither is the case. I've simply told you the result of a study.

In the Netherlands, where I live, there are many classes of vehicles which use the cycle-paths. They do this mostly without causing significant problems for one-another, except in some places where the infrastructure is inadequate. These vehicles include, but are not limited to:
  • normal bicycles
  • racing bicycles
  • recumbents
  • cargo bikes
  • e-bikes (25 km/h, as considered by the study)
  • e-cargo bikes (sometimes quite large for kindergarten use)
  • mopeds limited to 25 km/h
  • electric mopeds limited to 25 km/h.
In rural areas they are joined by similar classes of electric and internal combustion engine vehicles limited to 40 km/h. All these vehicles have been getting along quite well for a long time in the Netherlands.

I don't personally want an e-bike because it would not benefit me, but it doesn't concern me at all that other people ride them. That's their choice.

25 km/h e-bikes have a similar effect on other users of cycle-paths to 25 km/h mopeds, especially the electric versions which don't produce air pollution or noise. i.e. they don't cause a significant problem to other users of cycle-paths.

Your laws on e-bikes may be different. That's beyond the scope of this blog post and the study.

Isn't it the same as gearing/aerodynamic improvements/lighter components on a normal bike?
It's a popular line of argument to suggest that someone who is perceived as being "against" e-bikes would also argue against other improvements to bicycles. This is not a logical argument.

Any improvement to a bicycle which improves its efficiency will indeed allow the rider to travel a little further and/or faster for the same effort, but all the energy required to power that bicycle will still come from the rider.

Adding a motor to a bicycle has a very different effect: It makes pedaling to some extent optional. A modern pedelec requires the rider to turn the pedals, but it does not require them to push the pedals with any significant force. In the Netherlands there are hundreds of thousands of e-bikes. They are not used to travel significantly faster than non-assisted bikes, their riders just do less work. People who switch to an e-bike almost always get less exercise as a result.

No-one ever says "since I added an aerodynamic seat-post to my racing bike I've been able to ride to work without sweating", but plenty of people will tell you that their e-bike allows them to reach their destination without working up a sweat. That is made possible because the motor did the vast majority of the work.

The speed-pedelec of the 1970s. A friend of mine had one of
these. Did he pedal it? Of course not. Credit/rights: wikipedia
We've been here before
Ever since the invention of bicycles, people have added motors to them to increase speed or reduce the effort required of the rider. You can see this even from the etymology of words such as motorbike, moped, pedelec, e-bike, bromfiets, snorfiets. Several of these types of motorized bicycles have pedals.

How often do you see someone actually pedal a moped ? Often these pedals are designed only to meet a legal requirement to have pedals. It's actually easier not to bother with them. People who buy mopeds intend to use them as powered vehicles. The same is largely true for e-bikes. While it is possible to exercise on an e-bike, many owners use their electrically assisted bikes as if they are small motorbikes, putting in the minimum effort required to turn the pedals so that the motor operates.

See also my previous blog post about how pushing e-bikes won't result in mass cycling. The benefits for individuals and society that result from mass cycling come about when safe infrastructure is provided which encourages cycling. The answer is not a different type of bike, especially not one which doesn't require the user to push the pedals hard to make progress.

22 comments:

Andrew WD said...

A fair blog title might be 'e-bikes don't reduce rider BMI.'

But it's surely not accurate to claim that there are no health benefits.

Cleaner air is one health benefit. Another is reduced injury and death which is associated with widespread car usage. We might also look at things like commuter stress, livable streets, reduced environmental noise. It's a mistake to view health in such narrow terms as the BMI of a rider. Health can and should be assessed at a population as well as individual level.

David Hembrow said...

Andrew, thank you for your comment. I agree with all of what you've said. All those points are valid and they're all subjects of other posts on this blog. The study which this post is about, though, is limited only to the health benefits of the individual rider so I kept it short this time and wrote only about that.

Mattias said...

David, you agree to Andrew, but then you do it again with "the health benefits of the individual rider" or in the article "shouldn't be a surprise that the health benefits of cycling disappear if you fit a motor to a bicycle" or "If you're a healthy and able human then an e-bike is as bad for your health as any other motorized vehicle such as a motorbike or a car."

'Health' is not a synonym for 'BMI' or 'exercise'! It's a very important part of it, but after reading your text it's like I could as well use a car instead of an e-bike. Your article could be a text from the automobile lobby ;-).

David Hembrow said...

Mattias: You seem to be concerned that what I wrote in the blog post before I responded here to Andrew's comment hasn't been changed. I didn't change it because it remains correct. The study shows that the average user sees no health benefit from riding an electric bike over driving a car or using other kinds of motorized bicycle. To see personal health benefits due to exercise when travelling you have to use your own energy to propel yourself, either walking or by using a bicycle which you pedal and not one which is driven by a motor. That really shouldn't be any surprise to anyone...

Erwin said...

BMI can actually go up if you start to spend serious amounts of time cycling, as kilos of fat are exchanged for kilos of muscle. My own BMI has hardly changed when I went from 3000 km per year to 14000 km, but I'm much fitter now.

Greetings
Erwin and Tante Lies

Mattias said...

*sigh* You did it again :-)!

Health: Health may be defined as the ability to adapt and manage physical, mental and social challenges throughout life.

BMI: The BMI is an attempt to quantify the amount of tissue mass (muscle, fat, and bone) in an individual, and then categorize that person as underweight, normal weight, overweight, or obese based on that value.

Conclusion: health (benefit) and BMI (decrease) are not synonyms. Even 'physical' and 'BMI' are not synonyms.

The study you are referring to is talking about BMI. And indeed: an increase in BMI has a consequence for your health. But I don't follow the 'jump' to 'an e-bike is as bad for your health as any other motorized vehicle such as a motorbike or a car.'

I also want to refer to some lines in the study:
-) Due to the less frequent use of motorcycle and e-bike compared to other modes, confidence intervals were wider and mostly not statistically significant
-) Although the sample of e-bikers was small, riding an e-bike was associated with higher BMI. This finding could complement a previous study that found that older adults with a higher BMI were more likely to be an e-bike-user. This would indicate the presence of self-selection.
-) In the longitudinal analysis, we hypothesize that more frequent use of an e-bike leads to a higher BMI through less regular biking. However, it is unlikely that all of the weight gain was the result of reduced physical activity, as e-biking still requires moderate to vigorous levels of physical activity

To be clear: I agree that a person who uses an e-bike likely has a higher BMI than one who uses a regular bike. As a consequence it might be that that biker is less healthy. But I don't read your title 'Riding e-bikes does not lead to health benefits' in the study you are referring to...

Henrietteja said...

Het hangt er helemaal vanaf hoe je de e-bike gebruikt. Als je altijd in een hogere ondersteuning rijdt en niet je best doet om harder te fietsen, zal dit verhaal zeker opgaan.
Als je, zoals ik, bijna altijd met de laagste ondersteuning fietst en dan evenveel kracht gebruikt als op een gewone fiets, ga je harder en is het net zo goed voor je conditie.
En bovendien fietsen mensen met een e-bike vaker.
De verkopers van die fietsen mogen hier wel wat meer aandacht aan besteden. Dat kan ook best zonder belerend toontje.

David Hembrow said...

Erwin: What you said about BMI and muscle mass is of course absolutely true. However I don't think it really applies to this study, which is concerned with average people and not with athletes.

Mattias: I read the study and anyone else can do so too at the link above. There's no need to reproduce vast amounts of text here.

I did not invent the idea that this study reports on health benefits. You need read no further than the abstract to find the authors making the same connection with health: "Our analyses showed that people lower their BMI when starting or increasing cycling, demonstrating the health benefits of active mobility." Note that they are referring specifically to cycling. They always consider e-bikes as a separate category.

It is also not unreasonable that I suggest that e-bikes should can be lumped together with other modes of transport so far as their health benefits are concerned. The authors of the study do this too: "the results suggest a graded relation in terms of BMI: bike < walk < public transport < motorcycle or moped < e-bike < car." and again: "Our analyses further suggested a graded relationship with the lowest BMI in cyclists, followed by walking, public transport, motorcycle or moped, e-bike, and the highest BMI for car users."

Also note that the authors controlled to some extent for the case of people with less healthy BMIs choosing "less healthy" forms of transport: "when only considering people with a healthy BMI (below 25 kg/m 2 ) the effects were smaller but largely in the same direction."

Note that the confidence intervals are visible on the graph which I reproduced at the top of the blog post. The motorised modes have barely any negative content, while the non motorised modes (walking and cycling) are almost entirely negative. In particular, cycling and e-bikes have barely any overlap.

It's all quite conclusive. I think my title actually does agree with the study result.

Henriette: Ja het hangt wel vanaf hoe elke fietster gebruikt haar fiets. Maar, deze study gaat over de gemiddelde mens en de gemiddelde mens is lui. In mijn ervaring, e-bikes zijn altijd langzaam. Het is alsof er is een maximaal snelheid van 25 km/h (meestal wat minder). Bijna niemand gaat sneller dan zijn 'geassisteerde' snelheid omdat het de accu doet 90% van de werk.

In vergelijking, mijn gewone snelheid op mijn stadfiets zit tussen 27 en 30 km/h op korte tochtjes naar de stad en terug. E-bikers zijn behoorlijk moeilijk om in te halen omdat zij kunnen niets doen. Kan niet sneller en wil niet langzamer en daarom blijven naast elkaar rijden. Normale fietsers kunnen zijn snelheid makkelijker aanpassen, beetje snellere of langzamer om inhalen makelijker te maken omdat het energie komt uit zijn eigen spieren.

CevO said...

Googling for 30 seconds yielded these result:
https://www.ncbi.nlm.nih.gov/pubmed/27299435
https://insights.ovid.com/crossref?an=00042752-201805000-00002
https://www.medindia.net/news/riding-an-e-bike-benefits-health-and-fitness-181340-1.htm

Please note that the last link refers to a study among 65000 participants.

You have extensively reported on a study that looks at BMI only and not other aspects of a person's health. Cardiovascular and respiratory benefits are reported in all three studies I linked to. So your blog post is limited and just a tad tendentious. It certainly is not based on a thorough analysis of all studies out there and consequently comes up with incomplete conclusions. The blanket statement
"Riding e-bikes does not lead to health benefits" is just wrong and almost sounds like click-bait,


Belle said...

I have an e-trike and I have not seen any differences in my heart rate while training in a unmotorised velomobile or on my assisted trike. In both vehicles I put in my maximum effort. With the assisted trike the motor just adds extra speed. Without motor top speed is around 22 and with motor it is 32 for me. Same with the velomobile: the aerodynamics adds speed to my performance. Without the hull my cycle speed is way slower. This has to be a sloppy ‘research’. Can you compare the group of e-bikers with the group of unassisted cyclists? Most of the e-bikers in the Netherlands are older. Can you compare a car driver with a cyclist? Try to find a car driver that doesn't also regularly cycles (in the Netherlands hard to find). That researcher can bash e-bikes as often as (s)he likes but it won’t stop this evolution. There are already way more e-bikes sold than unassisted bikes. That trend is even more visible in European countries with mountains. The only people over there still riding unassisted bikes are old (fashioned) people.

David Hembrow said...

CevO: Thank you for your contribution. The studies that you refer to exist in the same universe as the study which I based the blog post on. They do not contradict each other, they merely ask different questions which have different answers. I'll explain how below:

You posted links to two studies (I believe two of your links refer to the same Basel study). First a correction: The Basel study didn't have 65000 participants, but 30 recruited out of the 65000 who took part in a national "Bike to Work". The second study had 20 participants. There are similarities in the studies because both took part over a month and both began with "untrained overweight" or "sedentary" individuals who were instructed to cycle a minimum amount over the month.

The question being asked in both these cases is a variation on "can people exercise with a pedelec should they want to ?". The answer in both cases came back as an emphatic "yes". I don't think this result is at all surprising given how those studies were run. The result showed that a motivated person can exercise on a pedelec (or normal bike) if they want to.

The study which I found interesting asked a very different question. They began with >3000 people who had already chosen a mode of transport (some changed during the study which complicated things, but they're treated differently). These people had already become used to their mode of transport. They were not selected as being untrained, overweight or sedentary and they were not instructed to do anything different to normal. They were measured at the beginning of the study and then 18 months later. A comparison was made to see what had happened to the participants and the result compared with transport mode.

The methodology isn't at all the same as the studies which you reference. It does not seek to answer the question "can people exercise with a pedelec ?". Rather, this study looked at what people in the real world do when left to their own devices over a longer period of time. The question asked was more akin to "How much exercise do users of different modes of transport actually get in real world use ?".

I have to point out that there is a fundamental difference between an e-bike and a normal bicycle.

On a normal bicycle, if you don't pedal you don't go anywhere. If you don't pedal quite hard then you go very slowly. There's a very strict relationship between work and result. It's the same with walking. You can walk very slowly with a minimum of effort, but if you need to get somewhere quickly you'll work up a sweat.

On a pedelec the connection between work and result is loosened. Yes you have to turn the pedals, but set to maximum assist and in top gear you only actually need to nominally turn them for the motor to push the bike at more or less its maximum assisted speed. While you have to turn the pedals, you don't have to do so with anything like enough effort to propel yourself so unless your aim is to get a workout you can arrive at your destination without much exertion or sweating. You can exercise if you want to, but it's been made (more or less) optional.

The results of the study suggest that people who use the active modes (walking and cycling) tend to get more exercise than those who use the motorized modes (car, motorbike and e-bike). It suggests that while e-bike riders could get exercise while they ride, many people who ride e-bikes actually choose to allow the motor to do nearly all the work and to save themselves from the effort required.

While the other studies ask what I saw as a fairly obvious question about mechanics, this study asked a less obvious question about human behaviour. I found this to be a far more interesting result. That's why I blogged about it.

David Hembrow said...

Belle: You're motivated to pedal with your maximum effort so of course you will get exercise when riding any bike. Anyone who is motivated to work hard can get exercise doing almost anything physical. That's obviously true. But it's not the question that this study sought to answer. Please see my reply to CevO above.

CevO said...

Hi David,

Thanks for getting back on this one. You're right, they refer to the same Basel study, two of them. I'm sorry, I was a bit rushed and I knew I'd seen some studies on e-bike health benefits before so I googled quickly without looking into which was which.

However, I absolutely disagree with your assessment on the objective and the outcome of the study. The objecive was not "can people exercise with a pedelec should they want to ?" nor was the outcome therefore an emphatic "yes". The study consisted in comparing the effect of exercise on both normal bikes and e-bikes for untrained individuals and to check some health parameters before and after the 4 week period during which each individual had to exercise (without requirements about the intensity levels) 3 times a week and cover a distance of at least 6 km. Let me quote the conclusion for you:

"Those who use e-bikes on a regular basis benefit permanently, not only in terms of their fitness, but also in terms of other factors such as blood pressure, fat metabolism, and overall mental well-being." Overall, he suggests that the study provides an important indication of the preventive potential of e-bikes.

So it's not about whether untrained individuals can get on an ebike and do exercise, the study actually showed improvemens on cardiovascular, respiratory and body fat related health parameters.

So I repeat: on the basis of one study that only looks at BMI as a health parameter you concluded "Riding e-bikes does not lead to health benefits". The studies I linked to show the exact opposite of that statement. Moreover, they take into account a wider scale of parameters that are aguably more reliable indicators of a person's health than the BMI index alone.

Your argument that the BMI study looked at long term effects of an exercise in people who had already been using their chosen mode of transport, or rather, the study's emphasis on that, does not in any way justify the title of your blog post either. Sure enough, if I walk 5 km each day during a year, and then after a year you start checking during an X period if my health keeps improving, that will obviously not be the case. Any exercise people perform without changing the length and / or the intensity, will lead to initial health benefits but after a while the improvement curve will flatten and a certain level of health optimization will be maintained, but not improved.

My conclusion: e-bikes undoubtedly bring benefits to improve people's health and neither your study nor the ones I linked to support your blanket statement that they don't.

BTW: I am aware of the differences between a pedelec and a normal bike. In fact, I own a pedelec, as well as a road bike and a mountain bike. I live in a mountainous area and am a pretty good mountain biker. Obviously, on the MTB I exercise harder, longer and more intensely than on the e-bike. The e-bike for me is not a replacement for the bike but for my car which I hardly use to commute anymore. My personal experience is that ebiking through the winter, when I don't get on the regular bike a lot due to weather and daylight constraints, helps me be in better shape when spring comes around, and the transition to taking the MTB out again is not as hard as when I was still using the car to get to work. Also, I notice my heart rate goes up and I lightly sweat when I bike to / from work on the pedelec. Of course, it's a lot less than on the normal bike which is fortunate since I don't want to arrive soaked at my work. But my body responds to the exercise on the ebike, which I always use in max assist mode by the way. So not only the studies, but my own empirical data contradict the title of your blog post.

David Hembrow said...

CevO: Regular exercise is required for health. It doesn't really matter too much how the exercise is taken, be that by bicycle, walking, or by pedaling an e-bike or a stationery exercise bike or other equipment. All those things can be used to exercise and it all will have a similar effect.

What is highlighted by this study is that the outcome for users of e-bikes is in fact similar to users of other motorized means of transport. Their outcome is not similar to that of people who walk or cycle.

You could see this as similar to the effect of buying membership of a gym on health. Some people join a gym, go regularly and get a lot of exercise by doing so. However these aren't the people who make gyms commercially successful. The economics of gyms rely on the fact that many people who buy membership actually don't use it much. Owning gym membership is analogous to buying and riding an e-bike. i.e. exercise is optional and many people don't take that opportunity.

Your personal experience is of course valid for yourself. But you're a person who cycles for exercise already and you do take the opportunity to exercise on an e-bike (albeit sometimes less if you don't want to arrive sweaty at work). But your experience is not everyone's experience.

I don't know your location but I'm Dutch and writing from the Netherlands. We have hundreds of thousands of e-bikes in use in this country. I've added a graph to the blogpost above which shows the average speeds of people riding e-bikes vs. normal bikes. You'll note that there is very little difference. Most people don't ride normal bikes fast enough to get a really good workout, and those who have switched to e-bikes are working even less hard.

In this country, bicycle sales are dropping overall and e-bike sales have climbed to a third of the remaining total. People are switching in large numbers from a mode of transport which required them to exercise (even if not much) to a mode on which they are clearly not exercising sufficiently. This is putting the health of the nation in jeopardy.

CevO said...

David,

You're shifting the goal posts. Whereas initially you post a blog entry with the title 'Riding e-bikes does not lead to health benefits', in my book a blanket statement that is not supported either by the study you referred to nor by the studies I linked to, you now argue the following:

1: e-bikes do not contribute to a better health in the way that walking or cycling does;
2: people in Holland will be less healthy by massively switching from regular bikes to e-bikes.

Those statements differ from your initial argument in this blog entry, which I have tried to refute by linking to other studies and by arguing that BMI is not the only parameter that can be used to check a person's health.

I of course agree that e-bikes in most cases will not give the health benefits that normal cycling or walking can give you (alhough it may be a good therapeutic means to get people started). I still do not agree with the title of your initial post, and from the looks of it you're having second thoughts about it as well since nothing you have said so far supports the claim that e-bikes in general do not contribute to a better health.

Mattias said...

David,

You are talking about no need for my vast amounts of text from the study, but those are important remarks to think of. The remark of Erwin as well (BMI and weight of fat vs muscles).

Concerning e-bikes I would have formulated the conclusion more like the following three paragraphs. I'm pretty sure there wouldn't have been 'bizarre responses'.

It's of no surprise that those who were hoping to have a smaller BMI by using an e-bike compared to a regular bike will be disappointed. What might surprise some is that those who use public transport have a bigger chance to have a smaller BMI than those who use an e-bike, due to the fact that they mostly walk or bike towards their stop.

Unfortunately the study doesn't address other possible health benefits from using an e-bike, especially compared to a car. Things like 'cleaner air' (because you might be able to use less polluted routes), anti-stress (no traffic jams), being able to empty your head, more possible social contact,...

From a broader perspective: if a very large portion of car drivers would switch to e-bikes it would have a extremely positive effect on the health of a lot of people. Not really because of a better BMI (as the study shows), but because of more space (for trees, to meet,...), less air pollution,etc etc etc etc. If only the regular bikers change their bike for an e-bike, there will be a negative evolution. Important remark: you can't push people out of their car and just put them on an (e-)bike, as you can read in the article 'Pushing e-bikes will not result in mass cycling '


David, I really appreciate all of your elaborate articles, very well written and balanced. It's the first time that I see you a little bit 'narrow-sighted'. Like CevO writes: you are shifting the goal posts, without really admitting that the original post was a bit 'tad tendentious'. Anyway, I'm still looking forward to a next article!

David Hembrow said...

CevO: The goal posts haven't moved a millimeter. The blog post has not been changed and what I was trying to communicate when I remote it also has not changed. You keep returning to the title which you seem to have misunderstood.

You've placed a lot of emphasis on the title and you've misunderstood it. Note the grammar: e-bikes is plural. Also, the use of passive voice. This title does not refer to what will happen to any individual. It refers to the result for the entire population.

Perhaps you picked up on the title because you are not impartial about e-bikes. It's a bland title in the passive voice but you appear to be trying to impart your own active meaning into it.

If I had written a blog post with some other passive voice title such as "cars get stuck in traffic jams", "actors aren't paid well", or "cyclists are fitter", I doubt you would have written to tell me that some people live where there's no traffic, that some actors are paid well or that a guy around the corner who owns a bike is unfit.

Somehow we have arrived at a place where I consistently explain that a study suggests that, in practice, across a population, choice of an e-bike doesn't result in riders doing much for their own health while you try to contradict me by saying that it's possible to get exercise by riding an e-bike. Those two things do not contradict each other.

Moving from the title to the first paragraph, you'll read an explanation of the title: It accurately reflects the result of an 18 month study of thousands of people. The study produced a ranking of different transport modes. I reproduce the ranking in textual and graphical form.

The study result places e-bikes between other motorized modes. I didn't invent this ranking nor did I change it; I merely reported it. Don't shoot the messenger !

I wrote a blog post about this study because the result is interesting. It's interesting because it is perhaps unexpected (you certainly don't seem to have expected it), also because the methodology gives an insight into the behaviour of humans left to their own devices. We are not ideal creatures, we're not always rational creatures and this study suggests that (on average) we're a pretty lazy bunch who will opt out of exercise when we can.

Your point 1 misrepresents the study result by being overly generous to e-bikes. Why ? Because you omitted the other modes to which e-bikes are comparable and included only the modes which you want to compare with. The study result\ doesn't show e-bikes with a health benefit similar to walking or cycling, it shows them to be no different to cars & motorbikes. All three motorized modes cluster together on the "wrong" side of the graph's horizontal black line. Based on the study result, if you wish to argue that e-bikes are nearly so good as cycling you also have to argue that that cars and motorbikes are the same. I doubt that you would want to make such an argument.

We can argue until the cows come home about whether this study result is wrong for one reason or another, but any such argument that we can have is based on nothing but speculation because neither you nor I have data to refute the result. Whether we like it or not, our opinions cannot change the study result. What's more, results from other unrelated studies which ask different questions, though they may also be entirely valid in their terms, cannot change the result of this study.

As for point 2: I used the people of my own country to provide a possibly explanation for why e-bikes don't do better in the study. E-bikers across the Netherlands (note: There are 12 provinces, two of which are "Holland") are only slightly faster than normal cyclists. This suggests that they use considerably less effort than cyclists. If a similar pattern is seen across the cities where the study took place it could explain the result.

David Hembrow said...

Mattias: Thanks for your comment. All the points out make about trees, air pollution, mental health, stress etc. are of course completely valid, especially if your point of view is from a country where it is hoped that people will take to e-biking instead of driving cars. I think chance of getting people to abandon cars and ride e-bikes on roads where people are still driving a lot is very limited and can happen only after safe infrastructure is provided.

While those things are valid, I didn't cover any of them for two reasons:
1. They're outside the scope of the study which I was blogging about, which is short on opinion and good on methodology so I really wanted to cover just that study and not confuse it with anything else.
2. You can't talk about absolutely everything in every blog post.

Of course my point of view is from my country, the Netherlands. Here we have falling sales of normal bicycles but a big increase in e-bikes to the extent that about 1/3 of "bicycles" now sold are e-bikes. People are even giving children e-bikes to ride to school. The increased use of e-bikes may well turn out badly for the Dutch: A high proportion of people's daily exercise was taken on bicycles in the past and this has played a part in keeping the population relatively healthy. The e-bike may well portend a decline in overall health of the Dutch population as people let the motor on their bike do the majority of the work on their local journeys. I'm not the first person to have made this point and I doubt I will be the last.

CevO said...

David,
I'll be brief since we are never going to agree.

I'm sure there are studies that tell me that Euro 6 cars with high-tech soot filters and running on bio-diesel contribute less to air pollution than old Ford Transit vans. So in your world I can then say: 'Driving diesel cars does not contribute to air pollution'. I invite you to re-read the title of your post again and then decide in all sincerity if it is a blanket statement or not.

For what it's worth: it's not a passive voice sentence either. That would have been 'Health benefits are not gained by riding e-bikes'. Blanket statements can be either passive or active voice.

Lastly: I know a thing or two about the Netherlands, since I am Dutch and lived there until 2002. Nowadays I live in Spain.

David Hembrow said...

CevO: It seems we disagree about language as well. Well, that's OK.

As for your question, if you were to use your title to report on a study which concluded that a particular class of diesel cars polluted less than old vans then you would need a title which suggested that one polluted less than the other. The title which you suggest makes a much bolder claim that that which would not be logically consistent with the study results. To use your title you would need to find a study which concluded that diesel cars in general do not pollute at all. If you could find such a study then your suggested title would make sense as a summary of that study.

In reality it's of course not really possible to make a serious argument that any kind of car does not pollute. Quite apart from anything else, there is much concern these days about particulate pollution and because most of that comes from the tyres and not the exhaust, it affects all cars. Even cars powered by electric motors create significant quantities of particulate pollution and so even those shouldn't really be claimed to cause no local pollution.

Your made up example brings to mind claims made by Volvo (and probably others) that some of their cars can actually make the air around them cleaner than it was before. The claim is of course quite limited, based around reducing some selected pollutants that they can deal with while ignoring others which they can't. It also requires the air which the car drives through was already very polluted by car exhaust before the Volvo arrived. If driven in a place with low or no pollution these cars most certainly leave air behind them which is more polluted.


The Netherlands is a great country in many ways, but the weather isn't really a highlight. I do hope you enjoy living in Spain.

Gentsracer 1 said...

I enjoyed the article and the discussion below. I think you're entirely right in your initial assessment and in your replies to the commenters below.
What's most unfortunate about e-bikes is how they now 'pollute' the wonderful means of transport that is cycling.
We're more and more disconnected from the real world of which our physical body is an integral part, to a point where we now destroy this very world on which we depend so totally. Cycling used to be something that could reconnect us to that world in many ways, while at the same time allowing us to transcend it. We could as it were lift ourselves above the world while still being totally grounded in it.
E-bikes are now emptying cycling of that force, tarnishing it, polluting it with laziness, physical and intellectual.

M Stoss said...

Thanks for sharing this study.