WS MoreOrLess: The Tour de France

Summary

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More or Less – The Tour de France & Lightning Deaths

Podcast: BBC Radio 4 – More or Less
Date: July 19, 2014
Host: Wesley Stevenson (filling in for Tim Harford)

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Episode Overview

This episode of “More or Less” investigates two intriguing topics:

1. The science behind why Tour de France climbers and sprinters look so different, including the numbers that explain who succeeds in the mountains versus the sprints.
2. Fact-checking the often-quoted statistic of 24,000 deaths caused by lightning worldwide each year and exploring the real risks.

The episode features expert interviews, illuminating data, and the show’s trademark skepticism about widely-cited numbers.

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1. Why Are Tour de France Riders So Different?

(Starts: 00:21)

The Anatomy of a Cyclist

• Sprinters vs. Climbers:

  • Sprinters like Marcel Kittel and Andre Greipel are described as “stocky and packed full of muscles.”
  • Climbers such as Vincenzo Nibali and Joaquim Rodriguez are “lithe and almost skeletal figures.”

• Expert Insight – Paolo Menaspa (01:05):

  • Explains the key difference is BMI (“body mass index”), not just weight or height.

  • Typical BMI: Climber ≈ 20; Sprinter ≈ 22–23.

  • Muscle volume is crucial for sprinters to produce the quick, high power needed for fast finishes.

    "Climbers are thinner and usually lighter. The constant thing is the BMI [...] usually around 20 for a climber. [...] Sprinters [...] are around 22, 23."
    —Paolo Menaspa, 01:05

The Physics of Racing

• Power vs. Resistance – Dr. Andy Kirkland (02:10):

  • On flat roads, “the greatest resistive force is aerodynamic drag,” so muscle mass helps.

  • On climbs, “about 5% gradient and more, gravity becomes the greatest force,” making extra muscle a hindrance.

  • Key metric: Power-to-weight ratio (“the power the rider delivers to the pedals divided by their weight”).

    “On a flat road, the greatest resistive force is aerodynamic drag... as soon as the gradient starts to increase, though, about 5% and more, then gravity becomes the greatest force acting, so that muscle becomes a hindrance to their ability to get up the hill quickly.”
    —Dr. Andy Kirkland, 02:25

• Typical Values:

  • Elite climbers sustain around 6 watts per kilo on major ascents.

    “A typical climber, say on a major climb, would be producing around about 6 watts per kilo.”
    —Dr. Andy Kirkland, 02:59

Who Can Win the Yellow Jersey? (03:32)

• Body Type & Race Profile:

  • The ideal physique depends on the year’s course design.

  • 2014’s race, with only one time trial, “suits climbers.”

  • Time trial specialists often have a BMI of 21–22.

    "Sometimes the Tour de France starts with a team time trial... and then you might target a heavier cyclist, someone with a BMI a bit higher. Time trialists, they often have a BMI around 21, 22."
    —Paolo Menaspa, 03:51

• Notable Evidence:

  • On mountain stages, sprinters like Marcel Kittel lose over 30 minutes (e.g., stage 10), highlighting the critical difference between athlete types.

    “The sprinter Marcel Kittel was 32 minutes down on the winner of that stage, Vincenzo Nibali.”
    —Wesley Stevenson, 04:24

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2. Do 24,000 People Really Die from Lightning Each Year?

(Starts: 05:15)

The Surprising Number

• The Claim:

  • Widely cited: 24,000 people killed by lightning a year worldwide (John Humphries, 05:15).

    “It’s something like 24,000 people a year worldwide get killed by lightning. It’s a major hazard.”
    —John Humphries, 05:15

• Plausibility Check – James Fletcher (05:50):

  • “In the UK... up to 60 people are hit by lightning each year and on average around three are killed.”
  • Most lightning deaths occur in Asia, South America, and Africa, but data is highly unreliable in those regions.

Where Did the Number Come From? (06:28)

• Origin of 24,000 Figure (06:32):

  • Based on a 2003 conference paper.

  • Extrapolated data from early 20th-century US statistics (6 deaths per million/year) to the ~4 billion people living in lightning-prone areas.

    “They estimated 4 billion people living in areas... susceptible to lightning. Lightning’s a very tropical thing, after all, and that’s how they got to 24,000 deaths.”
    —James Fletcher, 07:14

More Recent Estimates (07:56)

• Updated Study:

  • Extrapolates from improved statistics in some developing countries.

  • Produces a new estimate: 6,000 global lightning deaths per year — a quarter of the earlier figure.

    “This new method produces a new estimate. Global lightning fatalities are, on this method, around 6,000.”
    —James Fletcher, 08:16

Which Number Is Right? (08:19)

• Expert Uncertainty – Ron Holler:

  • Both figures are “educated guesses.”

  • The real number could swing between the two, and even experts can’t be sure.

    “Every day I look at reports of lightning fatalities and injuries... some days large numbers of cases come in and I said, well, maybe 24,000 is a reasonable number [...] other days or weeks it’s a little bit quieter, and said, well, maybe it’s really down around 6,000. I just don’t know. I would probably go for the higher number.”
    —Ron Holler, 08:23

• Bottom Line:

  • There’s huge uncertainty about the true global figure due to lack of good data from key regions.

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Notable Quotes

• On Physique:

  • "Climbers are thinner and usually lighter... BMI is usually around 20 for a climber." —Paolo Menaspa, 01:05
  • “On a flat road, the greatest resistive force is aerodynamic drag... As soon as the gradient starts to increase... gravity becomes the greatest force acting.” —Dr. Andy Kirkland, 02:25

• On Lightning Deaths:

  • “It’s something like 24,000 people a year worldwide get killed by lightning.” —John Humphries, 05:15
  • “I just don’t know. I would probably go for the higher number.” —Ron Holler, 08:23

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Key Timestamps

• 00:21: Start of Tour de France segment
• 01:05: Paolo Menaspa explains climber vs. sprinter physiques
• 02:10: Dr. Andy Kirkland explains cycling physics
• 03:51: How race design affects the best physique for winning
• 05:15: Lightning death statistic segment begins
• 06:32: Origin of the 24,000 deaths figure
• 07:56: New estimate of 6,000 fatalities; ongoing uncertainty

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Tone & Language

• The episode maintains a clear, accessible, and lightly skeptical tone, inviting experts to explain complex ideas in straightforward language.
• There is a strong emphasis on questioning accepted “facts” and revealing the uncertainty underlying many commonly repeated statistics.

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This episode is highly recommended for listeners interested in the facts behind sporting performance, the pitfalls of seemingly authoritative statistics, and how nuanced the search for “truth” in numbers can be.

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Transcript

[BBC Announcer]

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[Wesley Stevenson]

Hello, welcome to more or less on the BBC world service. I'm wesley stevenson. The Tour de France is in the main mountains and there's a change of personnel at the front. The sprinters like Marcel Kittel and Andre Greipel are taking a back seat. This is the territory of climbers like Vincenzo Nibali and Joachim Rodriguez. But why is it that the riders in the Tour de France are physically so different? The sprinters are stocky and packed full of muscles, but the climbers are lithe and almost skeletal figures. Paolo Menaspa is a physiologist and cycling coach who studies at the Australian Institute of Sport.

[Paolo Menaspa]

Climbers are thinner and usually lighter. The constant thing is the bmi, so the body mass index, which is a sort of a ratio between body weight and their height, and this BMI is usually around 20 for a climber. On the other side, the sprinters, they need much more muscle. There are studies showing the ability to produce a lot of power, which translates into speed, is correlated with the volume of the lower limb muscle. What makes the difference is the ratio between their height and their body weight. And usually sprinters, going back to that body mass index, they are around 22, 23, which is the number of kilogram for meter square.

[Wesley Stevenson]

And these differences mean that the sprinters don't climb that well. But why? I mean, the mountains in the Alps and the Pyrenees look pretty mean and require 30 to 40 minutes of solid climbing. So you might think the man with the muscles would thrive in this environment. To answer this, you need to turn to a bit of physics and the two elements to cycling which determine the speed.

[Dr. Andy Kirkland]

You've got the power that the cyclist applies at the pedals, and they've got to overcome the resistive forces that are acting to slow them down.

[Wesley Stevenson]

Dr. Andy Kirkland, coach and education officer at British Cycling so, on a flat

[Dr. Andy Kirkland]

rod, the greatest resistive force is aerodynamic drag. So the more power they can apply to overcome that drag on a flat road, the faster they're going to go. So to an extent, a bit of muscle will help there. As soon as the gradient starts to increase, though, about 5% and more, then gravity becomes the greatest force acting, so that muscle becomes a hindrance to their ability to get up the hill quickly.

[Wesley Stevenson]

But why would it be a hindrance? Bigger Muscles produce more power, don't they?

[Dr. Andy Kirkland]

Definitely. So we would be looking at a balance between power and weight, and we call that the power to weight ratio. That's the power the rider delivers to the pedals divided by their weight. A typical climber, say on a major climb, would be producing around about 6 watts per kilo as that body mass increases. Typically, we'll see on these mountain stages that they're not able to sustain such a high power to weight ratio when they're climbing.

[Wesley Stevenson]

And for sprinters, they need muscles for the burst. The sprints at the end of each stage are often won in the last 10 to 15 seconds. So is the best physique to win the yellow jersey somewhere in between the two? Well, that's not so easy to say, because Paolo Menaspa told me that depends on the course.

[Paolo Menaspa]

Every year is a bit different. For example, the 2014 Tour de France only has one time trial, so it's probably a Tour that suits climbers. So you definitely want a lighter contender. And the BMI has to be low, no doubt about that. Sometimes the Tour de France starts with a team time trial and then maybe a two time trial in the old course and bit less mountain stages. And then in that case you might target an heavier cyclist, someone with a BMI a bit higher trend. Trial trialists, they often have a BMI around 21, 22.

[Wesley Stevenson]

So the expert climbers sometimes do well, and other years it's more suited to the time trialists. One thing we do know is that sprinters won't win. If you look at stage 10 of this year's Tour, the first of the really mountainous stages, the sprinter Marcel Kittel was 32 minutes down on the winner of that stage, Vincento Nibali. Compare that to one of the stages that Kittel won and. And Nibali crosses the line just seconds behind. And that's why Nibali's a contender for the yellow jersey and Kittel isn't. Now, that's the music of Beethoven evoking thunder and lightning in his sixth Symphony. And we turn to an item that featured on BBC Radio in the UK recently about how solar activity might be triggering lightning strikes on Earth.

[John Humphries]

Anything that can help us predict the severity of lightning has got to be useful. It's something like 24,000 people a year worldwide get killed by lightning. So it's 24,000 a year. It's a major hazard. Yes.

[Wesley Stevenson]

And John Humphries wasn't the only one surprised by that statistic. Our inbox lit up with questions from listeners Essentially all asking, can this be true? 65 people a day killed by lightning. James Fletcher's here. James, it does sound implausible, given that being struck by lightning is the standard metaphor for something nasty. That's also extremely unlikely.

[James Fletcher]

It does, but if you're in doubt, you can do a quick sanity check by searching an online news aggregator for lightning deaths. And if you do, you'll see that people are indeed being killed all the time around the world. But getting a more accurate number is not so easy. There are only about 20 countries who keep an accurate track of lightning fatalities. In the UK, for instance, we know that up to 60 people are hit by lightning each year and on average around three are killed. So we have those statistics. But lightning is a lot more prevalent in Asia, South America and Africa, where billions of people live. And we have very sketchy data on lightning deaths in those places.

[Wesley Stevenson]

So where does the figure of 24,000 come from? Because it's quite widely cited.

[James Fletcher]

It is a figure you hear a bit. And the number comes from a conference paper published in 2003. The authors are two lightning experts who tried to come up with a reasonable way to estimate global deaths. The challenge is that while the good data comes from industrialised countries, lightning's more dangerous in less developed places because cars

[Wesley Stevenson]

or houses with metal plumbing provide some protection against lightning. And what's really dangerous is working all day out in a field somewhere. So you'd expect rural agriculture and poorer societies to lose more people to lightning.

[James Fletcher]

And you can add to that the fact that the standard of medical care won't be as good.

[Wesley Stevenson]

So what we're looking for is a place with rich country statistics but poor country lifestyles.

[James Fletcher]

And these experts found a very good candidate where? The United States of America. A hundred years ago, it was a rural society with very few cars and naturally no access to modern healthcare, but which nevertheless kept statistics on lightning strikes. Now, the death rate from lightning back Then was about 6 deaths per million people every year. The authors then applied that to the 4 billion people that they estimated were living in areas of the world that are susceptible to lightning strikes. Lightning's a very tropical thing, after all, and that's how they got to 24,000 deaths. But the authors are very open about the fact that that's a rough calculation.

[Wesley Stevenson]

So are there any more recent or better estimates?

[James Fletcher]

Well, one of the authors of the earlier estimate, Ron Holler, has been involved with a more recent attempt to come up with a better number, extrapolating from some of the new, improved statistics from certain developing countries most affected by lightning. This new method produces a new estimate. Global lightning fatalities are on this method, around 6,000.

[Wesley Stevenson]

That's a quarter of the size. Which number is better?

[James Fletcher]

Well, they're both educated guesses and I asked Ron Holler which he'd go for.

[Ron Holler]

I don't really know whether it's closer to one or the other. Every day I look at reports of lightning fatalities and injuries around the world and some days large numbers of cases come in and I said, well, maybe 24,000 is a reasonable number and other days or weeks it's a little bit quieter, and said, well, maybe it's really down around 6,000. I just don't know. I would probably go for the higher number.

[James Fletcher]

Other people I contacted favoured the lower 6,000 figure, so I guess that's just a sign of how little we really know about this.

[Wesley Stevenson]

Thanks, James. And if you have a number you want to investigate, then get in touch. You can email us at More or lessbc co and you can find out the odds of Charlie getting a golden ticket or whether we really are producing a generation of children who will die younger than their parents by listening to other editions of the [e-mail] more or less.

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