JOE PALCA, host:

From NPR News, this is TALK OF THE NATION/SCIENCE FRIDAY. I'm Joe Palca.

The world's most famous bicycle race finishes this weekend, and it looks like there'll be a familiar face on the victory stand. Lance Armstrong is on the verge of winning his seventh consecutive Tour de France. He's been wearing the leader's yellow jersey almost every day since stage four and seems unstoppable. So how does he do it?

Well, no doubt, part of the answer is intangible, but some of it is physiology, and that we can try to explain. For the rest of this hour, we'll talk about what kind of conditioning it takes to become a first-class cyclist and what's special about Lance Armstrong's physiology. We'll also talk about bike science in general: how to make a really fast bike and, for that matter, what physical forces keep a bike upright? If you'd like to join our conversation this afternoon, our phone number is (800) 989-8255; that's (800) 989-TALK. If you'd like more information about the science of cycling, check out our Web site at, where you'll find links to our topic.

Now let me introduce our guests. Ed Coyle is a professor in the department of kinesiology and director of the Human Performance Laboratory at the University of Texas at Austin, and he's founder of--excuse Dr. Coyle authored a paper which appeared in last month's Journal of Applied Physiology that described his studies of Lance Armstrong's physiology over six years of training. He joins us now from the studios of member station KUT in Austin.

Welcome to SCIENCE FRIDAY, Dr. Coyle.

Dr. ED COYLE (Director, Human Performance Laboratory, University of Texas, Austin): Yes. Good afternoon, Joe.

PALCA: Afternoon. And also with us is David Gordon Wilson. He's professor emeritus at MIT's department of mechanical engineering and chief scientist at Wilson TurboPower. He's the author of "Bicycling Science," and the third edition of that book was published by MIT Press in 2004. He joins us from member station WBUR in Boston.

Welcome to the show, Dr. Wilson.

Dr. DAVID GORDON WILSON (Author, "Bicycling Science"): Thank you, Joe.

PALCA: So I should start with you, Ed Coyle. First of all, I'm just curious--how did it happen that you wound up studying Lance Armstrong? Is this--I mean, are you particularly interested in cycling yourself, or did he stumble into your lab one day, or what happened?

Dr. COYLE: Well, my lab studies exercise physiology in people, and cyclists are good subjects, and we've been testing many competitive cyclists for over 20 years. And so, essentially, when Lance moved to Austin when he was 20 years old, his cycling buddies and competitors dragged him into lab and said, `Find out what makes this guy tick. He's going to be pretty good.'

PALCA: And so could you see anything--well, first of all, what kinds of things do you measure when you're studying the physiology and, I guess--yeah, physiology--I guess that's the word I want--of a cyclist?

Dr. COYLE: Exactly. We, you know, measure his maximal oxygen uptake, a measure of his cardiovascular function, see how well his heart can pump blood and how well his muscles can extract oxygen from the blood supply, see how fatigued his muscles are by--we do muscle biopsies occasionally and measure acid in the muscle, or we can measure acid in the bloodstream. We do biomechanics to measure cycling technique. So really, you know, it's like a specialized shop for racing to put the parts together and see what the limiting factors are.

PALCA: And was there something that initially stood out about his abilities that you could see set him apart?

Dr. COYLE: Yes. Besides his psychological focus, physiologically, he was a kid with a very large ability to pump blood, to consume oxygen--he had a very high maximal oxygen uptake; that is, the ability to produce raw energy aerobically. However, he was, you know, not very efficient at converting that into power, the bicycle--pushing down on the pedals or moving his legs. That's something he required years, seven years, to improve.

PALCA: And by--what do you mean by efficiency? What--how do you measure that?

Dr. COYLE: That we determine by when he's cycling at a stationary ergometer in the laboratory, we can measure accurately how many watts...

PALCA: I'm sorry--ergometer?

Dr. COYLE: Ergometer. So that's...

PALCA: What's that?

Dr. COYLE: A bicycle.


Dr. COYLE: That--an erg meter, or work power meter. So we can see how much power or work he's doing, and we measure how much energy his body is expending to do that. We do that by measuring oxygen consumption and converting that to calories a minute or even watts. And it turns out that most people are about 20 percent efficient, and car engines, by the way, are about 5 to 8 percent efficient, I believe that is, at taking the raw energy from the burning of fuels--gasoline, or food in people's case--and converting that raw energy into usable mechanical power.

So Lance was 20 percent efficient when he first came in, and he was able to increase that, remarkably, to 23 percent over seven years. It took seven years of continued hard training, and he progressed steadily over that period. We attribute that to him altering the biochemistry of his muscle, changing the types of proteins, from fast-twitch muscle fibers to slow, and the slow-twitch are more efficient. It's almost like converting the cylinders and pistons in a car engine so that you get more of the energy from the explosion in the cylinder being transmitted into the pistons themself.

PALCA: Well, I wonder, David Wilson, if I can move for a moment from the physiology to the mechanical. Is there, you know, something that Lance Armstrong can do with his bike or his riding position or something like that that makes him a more powerful rider?

Dr. WILSON: Well, I'm sure riding position has a great deal to do with it. A lot of work has been put into trying to find out why some riders go faster than others, even though Ed might have measured them and found them exactly the same or maybe in the reverse direction. But some people go faster, and it turns out their bodies, or the way they hold their bodies, have a lower air drag. An air drag at the speeds that Lance goes and other record bicyclists--they go at 25, 30, 35, even 40 miles an hour on the level, and then they go faster downhill. And an air drag is by far the greatest resistance they have to overcome.

PALCA: Really? Now I've always wondered--I mean, they make these things--I think you refer to them in your book as--well, they're called fairings, which are ways of deflecting or making your--more streamlined, but they don't use those in bicycle races.

Dr. WILSON: Well, that's part of the--that's something historical. In 1899, the racers of the world got--I guess they probably got fed up of all the changes that happened. You know, they'd just get used to winning on non-pneumatic tires, and then John Dunlop brought in pneumatic tires, and all the people with pneumatic tires won, and so on. So they brought in this group called the--how could--it's escaped my mind--the UCI...

PALCA: Yeah.

Dr. WILSON: ...Union Cycliste Internationale...

PALCA: There you are.

Dr. WILSON: ...and they have very strict rules that change very, very slowly, like an oil tanker. They change every two or three decades; they allow some slight change, like the shape of a tube, but otherwise practically nothing. So there's that group of bicyclists, whom we revere and honor. And then, back in '74, '5 and '6, a man named Chet Kyle and Jack Lambie, his friend in California, introduced another system of bicycling which allowed fairings.

PALCA: Uh-huh. Now--but there is a way, even in a race like the Tour de France, that at least some riders get some protection from the wind. Maybe you can explain how that works, and why they tend to ride in these packs.

Dr. WILSON: Right. There's a big difference between riding in the front of a pack and riding second or third. There's something like a 10 percent difference in air drag, which is enormous. And so somebody in a well-organized pack--and we've heard a lot about these pelotons being well-organized or disheveled or something like that. But Lance Armstrong is in an excellent pack, and people take turns to ride in front of him...

PALCA: I see.

Dr. WILSON: ...until the moment when they've given the breakaway and he can rush off and demolish the opposition.

PALCA: So peloton being the name of this group of riders that ride together.

Dr. WILSON: Well, I think it is. I was afraid you'd ask me that, and maybe Ed can straighten me out.

PALCA: Well...

Dr. WILSON: My wife was asking me, `What's a peloton?' And I said, `It's a group.'

Dr. COYLE: That's exactly right.

PALCA: Yeah. Yeah.

Dr. WILSON: Oh, good.

PALCA: I--oh, well, that's good. So--but the question I have are these things called breakaways--maybe, Ed Coyle, you're the right person to ask about this. It seems as if riders can suddenly put on this tremendous burst of speed, but then they have to stop for a little while and they go back to what is still fast for any normal human being, but doesn't seem to be, you know, the all-out sprint that they were doing. What's that all about, from a physiology standpoint?

Dr. COYLE: Well, it's interval training, essentially, in a bicycle race.

PALCA: It's--sorry, what was that word that you used?

Dr. COYLE: Interval...

PALCA: Interval. Oh, I see. OK.

Dr. COYLE: ...going hard and then easy, and as David mentioned, it's so hard to lead so that if they try and break away, they have to open a big enough gap so that somebody can accelerate and catch them and essentially draft on them and take it easy, and then just wait till they tire out and leave them. So bicycle racing has tremendous strategy, and it's very much a team sport and people working together to try and chase down these breaks and forming alliances. So it's like a mini-United Nations trying to figure things out on the roll during a race.

PALCA: But is there something that's happening inside the muscle that's limiting just how long you can keep up that kind of fantastic sprinting pace?

Dr. COYLE: Definitely.

PALCA: What? What's happening?

Dr. COYLE: When you go--you're building up acid in the muscle, lactic acid, and that causes the muscle fibers to fatigue. They just aren't able to contract; no matter how hard you try, you have to slow down. So one of the characteristics of Lance Armstrong is that he's able to recover very quickly. He doesn't fatigue as much in the first place. And where the pace gets very high and they can't break away and they have--they get caught by the pack, other people are still fatigued after 30 or 40 seconds. Lance isn't, and he's able to attack again and eventually break away from the field.

PALCA: Interesting. Well, let's invite our listeners to join the conversation. Our number is (800) 989-8255. And why don't we go to Brian in Columbus, Ohio. Brian, welcome to the program. What's your question?

BRIAN (Caller): Hi. Thanks, Joe. You do a great job, by the way.

PALCA: Oh, thank you very much.

BRIAN: Say, I had a question for Dr. Coyle. I've heard that Lance has an unusually large heart. I was wondering if that's true.

PALCA: Hm. Interesting.

Dr. COYLE: It is true, and it depends on how you define unusual. I think most top-level endurance athletes are going to have a heart that is about 20 to 30 percent larger than the average person. They maybe started out with a heart, genetically, that was 10 percent larger, but then grew that heart additionally, with intense training, three or four years of very intense training. So I think Lance--you know, Lance's heart is probably comparable to a number of other top endurance athletes--runners and bicyclists. He does have a high maximal heart rate, though. His heart can pump a lot of blood per beat, but it also can beat at very high rates, at a maximal rate of over 200 beats per minute.

PALCA: All right. Interesting.

BRIAN: Thank you.

PALCA: Thanks for that call, Brian.

Let's take another call now from Curt(ph) in Oakland--hold on a second. There we go, Curt from Oakland, California. Curt, welcome to the program.

CURT (Caller): Thank you very much. Good afternoon, everybody. I'm so thrilled to be on SCIENCE FRIDAY. I'm a longtime cyclist and SCIENCE FRIDAY listener.

PALCA: Wow. Not at the same time.

CURT: (Laughing) Sometimes, yeah.

PALCA: You're not riding now, are you?

CURT: No, I'm not.

PALCA: Oh, good. OK. Well, then I feel comfortable in asking your question.

CURT: I just wanted to debunk a typical, longtime myth that I grew up listening to, and I'm sure--is it Dr. Wilson?

PALCA: Yeah.

Dr. WILSON: Dave Wilson. Yeah.

CURT: ...will add to it. But I grew up being told the gyroscopic effect keeps the bicycle upright. And I learned after a few years of physics that it's actually the frame design that keeps the bike up and offset and resulting trail. And even though the front wheel does contribute to steering, it's really the frame and front-end design that makes a bicycle steer when you lean left by turning the front wheel left. So that would be my comment. And I have to say to Mr. Armstrong, `Go, Lance.'

PALCA: OK, Curt.

Well, Professor Wilson, before--I just want to remind people that they're listening to TALK OF THE NATION from NPR News. Dr. Wilson, you do address that question in your book. Maybe you can explain what it is about the frame design that allows us to keep a bike upright.

Dr. WILSON: Well, I'm not sure whether it's really the frame design, because people have changed the frames in all kinds of ways--they've made choppers, they've made the head angle, as we call the steering angle, vertical instead of sloped back. And people can still balance rather well. And, in fact, standing upright--I mean keeping the bike upright is just a matter of steering under the fall in the same way as if you got a broomstick on your finger; if you step forward to the right, you move your hand to the right and then it begins to fall to the left, and so on. So that's really all it is. There's been a kind of cottage industry the last few decades on making unridable bicycles. And a chap in Britain whose name has suddenly escaped me, I'm sorry, but...

PALCA: That's all right.

Dr. WILSON: ...he canceled out the gyroscopic effect by putting a counter-rotating wheel just off the ground just by the front wheel. Had no effect pretty well on how well anybody could ride it and so on. And so they found that almost anything can be overcome by somebody being able to ride properly unless you actually stop the steering moving, and then that sends you over rather fast.

PALCA: So--that's the interesting thing. So if you have a bicycle that you can't turn the wheel on at all, the front wheel, then that's the hardest one to ride.

Dr. WILSON: Yeah, that's really impossible. That's how bicycles started in 1816, '17. Somebody made a steerable bike and it wasn't a bike you pedaled, it was a bike you pushed on the ground. But that amazed everybody, that somebody could actually stay upright. And they've been doing it ever since. Well, if you look at one of those, they're called draisines because they were designed by Karl von Drais in Germany, and you say, well, how the heck could anybody stay upright on that, because the steering has got a huge amount of friction and so on. But they did it.

PALCA: Really? And you said--I like this concept. You say you steer under the fall. Can you explain that? I mean, you use the broom analogy. But let's say you're on a bicycle and you start to notice that you're tipping over to the left. What do you do with the handlebars? Because I don't think anybody who rides a bike really thinks about it anymore.

Dr. WILSON: No, you don't think about it. And it's rather amazing because, in fact, you then must steer to the left. Sometimes you do a little anticipatory jiggle to the right to make you fall over faster if you want to, for instance, turn left, and then you need to fall over so that you can turn fast without tipping over to the right because you're turning to the left. So you do a little wiggle to the right, and that starts you falling to the left, and then you steer to the left and so on. So your brain is very, very sophisticated at learning how to do these things.

PALCA: But they say once you've figured it out--that's why it's sort of like a one-trial--you either don't have it--I've watched my children as they learned to ride, and at one point they get it, and suddenly they can ride.

Dr. WILSON: Yes and no. Yes, I mean, that's true, you really can't lose that ability. However, we have a little family of three at the moment, my wife and myself and our daughter, and we have a triple-place tandem. And I call it a daughter delivery vehicle, because I take her places. And after I've dropped her off, and particularly if my wife gets off, I wobble like crazy for the next half mile trying to relearn the mechanics of the bike because it can be completely changed by people getting off it. So you don't learn everything about biking. If you have a new bike, if I change even from one bike to another--it looks the same--I wobble for a little while, while my brain gets retuned.

PALCA: And the other thing is, I think we've all seen--or we've all experienced--that as you turn or corner to the left, your whole body tends to lean to the left. What's that all about?

Dr. WILSON: Well, it's just like a plane--not exactly like a plane, of course, but I often think, when I'm coming into Boston and I'm finishing my drink or something like that, and I look down and I say, `My Lord, the wing tip's pointing right down at one of the islands in the harbor,' and I didn't know I was tilted over at all. So you can tilt it in the same way on a bike. You can keep absolutely in line with the wheels and feel very comfortable about it. You can also, if you wish, do what we call body English. I don't know if the French call it body French or what...

PALCA: Probably.

Dr. WILSON: ...but--yeah. You can lean more than the bike or less than the bike, you know, to accomplish other things. But if we just talk about being comfortable on a bike, we generally stay in line.

PALCA: All right. Well, we have to take a short break, but we'll be taking more of your calls at (800) 989-8255 and talking about bicycles--what keeps them up, what makes them go fast, and how you can train to become Lance Armstrong. Well, probably not just like Lance Armstrong, but something like that. Stay with us.

This is TALK OF THE NATION from NPR News.


PALCA: From NPR News, this is TALK OF THE NATION/SCIENCE FRIDAY and I'm Joe Palca.

We're talking this hour about bike science. My guests are Dave Wilson--he's a professor emeritus at MIT's department of mechanical engineering--and Ed Coyle. He's a professor in the department of kinesiology and director of the Human Performance Laboratory at the University of Texas at Austin.

And let's take some more of your calls at (800) 989-8255. And let's go to Peter in San Francisco. Peter, welcome to SCIENCE FRIDAY. What's your question?

PETER (Caller): Hi. I want to know--I'm sure a lot of people want to know, especially those people riding along with Lance--how he does it. And I heard that he was a swimmer early on. And I wondered if his training as a swimmer has given him any kind of an edge physiologically, where he gets to use his oxygen more effectively, or if that makes a difference. And I'd like to know...


PETER: ...if you can answer that.

PALCA: Sure. Peter, good question.

Ed Coyle, do you want to take a stab at that?

Prof. COYLE: Yes. Lance was a swimmer when he was a teen-ager, before he became a runner for his high school and then triathlete and professional cyclist at age 20. The swimming really, you know, involves the upper body mostly, and probably that didn't help him, although swimming is good for developing your heart. So that might have had a little carryover. But Lance also learned that in swimming, you train by doing intervals, swimming for two or three minutes and resting. So he was really used to going very intense. And swimmers also train for long periods. So I think also the mind-set, the culture of swimming helped carry over into his cycling training.

PALCA: OK, Peter, thanks for that question.

Let's take another call now from Thomas, Thomas in St. Louis, Missouri, I presume. Welcome to the program. What's your question?

THOMAS (Caller): Hi. Thanks for taking my call. Basically, my question is, what prevents us from creating a higher gear ratio to increase the efficiency of foot pedal rotation? Is it more of an equilibrium with wind resistance or is it like a tensile crank for the metal outlay?

PALCA: Interesting. Well, Thomas, before I let David Wilson talk about that, I'm going to make him explain what gear ratios are all about, because bicyclists are always talking about gears and gear ratios, but I presume these are the derailleurs at the back of the bike that shift gears and make it either harder or easier to pedal, right?

Dr. WILSON: Sure. In fact, when bikes started, they, of course, had no gears, you just pedaled the front wheel. And people had bikes made to fit their leg length because they wanted to have real big wheels. If you were tall enough, you had a 16-inch wheel, which is why we talk about a 16-inch gear now. So we often in our middle years are often about 60 inches, and our low gears--nowadays you get a mountain bike and go down 16 inches, call it granny gear, and that's as if you were pedaling a bike with a 16-inch wheel.

PALCA: So but the question then becomes, is there some limit? I mean, could you make a gear that would make it, you know, very, very, very, very hard to pedal so you'd have to have tremendous strength in your legs, but therefore go very fast?

Dr. WILSON: Well, stand by for a commercial. I should point out that Eddie is a professor and this is his professional field. So you should listen to him much better than to me because biking is a hobby with me; I'm a turbine specialist. And to my delight, bicyclists or human beings have the same output as a turbine, the same type of curve. And so if you imagine that you were Atlas lifting the world and you were pushing like crazy but the world didn't move, so you're developing a lot of strength, a lot of push. But now on the other end of this scale, if you are doing some boxing training and you're punching the air, your arms are moving very fast but you're not doing any work. So you've got those two extremes in which you're doing zero work, when you're not moving your hands and when you're moving your hands like crazy. And in between you develop maximum work and something like maximum efficiency. And that's what the purpose of gears are, is so that when you want to develop the maximum amount of power, you want to go at this intermediate speed. And that depends on what sort of person you are and what stage you are in training and how tired you are. I'm sure Lance might like a different gear ratio at the beginning of a climb than the end of a climb because he's tired out by then. But that's the whole purpose of gears, are to get you working at the right gear ratio. It's not as if you had an unlimited amount of torque and therefore you would put it in a very high gear and go fast. You can't do that.

PALCA: Right. OK, Thomas, thanks for that call.

Maybe I can just ask Ed Coyle then to comment. Is there some best way to pedal--fast and keep a steady cadence or what?

Prof. COYLE: Yes, there certainly is. And as Dave mentioned, it depends on the power you're producing. So for a certain level of power output, there's a certain optimal cadence, a cadence of peak efficiency. And then that changes a little bit with each person because each person can have different types of muscle fibers--fast, twitch and slow. And they differ in their velocities at peak efficiency. What we've seen in Armstrong, for example, is that when he's generating about 450 watts of power, his optimal velocity is about 120 revolutions per minute now. It used to be a little lower, but he's increased his power output and he changes muscles. And so certainly your chosen cadence does represent the right balance of who you are and how much power you're producing.

PALCA: OK. Let's go to Brad in Fairfax, California. Brad, welcome to the program.

BRAD (Caller): Hi. Thank you.

PALCA: Hi. Thanks for joining us. What's your question?

BRAD: Well, my question has to do with Lance Armstrong. I was riding once a while ago just before Lance found out that he had cancer. And I was riding along and this guy came up and started riding with me, and we started talking. And at the time, I didn't really follow bicycle riding at all. And he introduced himself as Lance Armstrong, and we rode for maybe a half-hour, 45 minutes. And what really struck me about him was how incredibly kind and, like, big-hearted he is as a person. Like, there was an overwhelming kind of kindness about him. And I wonder if some sort of, like, psychological aspects like that have an effect on his success.

PALCA: Interesting question. You're sure it was the Lance Armstrong?

BRAD: Yes, I'm quite sure.


BRAD: Now I'm quite sure, yeah.

PALCA: OK. Brad, thanks for that call.

Ed Coyle, goodwill part of cycling, cycle racing or not?

Prof. COYLE: Well, not to your competitors during the race.

PALCA: So if you ride along with somebody in Fairfax, California, maybe, but...

Prof. COYLE: No, but Lance is a very nice man, and when he's not racing, he's very kind. When he comes into the lab, he always asks us where he can place his bicycle; he doesn't just throw it somewhere. And he does ride with a lot of non-professionals. You'll see that, that although he's professional, one of the fastest, he'll perform his four- to six-hour rides with recreational bicyclists, and he's taking it very easy and socializing. And that's a very enjoyable part of those long hours of training.

PALCA: Interesting.

You know, David Wilson, I wonder if I could ask you, we've been talking about the fact that the bicycle hasn't changed very much, but there have been--well, it's certainly changed, but at least the bicycles you can use in racing have not changed all that much. But it does seem like wheels are made of new materials and brakes are made of new materials. What's been happening in that part of bicycling?

Dr. WILSON: One of the amazing things to me, anyhow, is the rise of mountain biking and how that has brought about a lot of new technology. As an engineer, I'm very unhappy with bike scientists. I have been from my youth, about the things that go wrong with bikes because it seems to me often that the manufacturers are sitting fat and happy and they don't ride bikes anymore and they don't understand what goes wrong with them. Well, the mountain bikes have introduced--the disc brake is terrific nowadays. I'm switching to disc brakes as soon as I can get a bike I'm working on finished in the basement because...

PALCA: So what's a disc brake as opposed--well, what are bikes typically using and what's a disc brake?

Dr. WILSON: Well, to start with, the bikes had a little spoon that ran on the top of the tire, and that was in the 1860s and 1870s and so on. And then somewhere about in the 1890s there was a caliper brake, something that came up under the rim and was pulled upwards, but that's not exactly a caliper brake. But soon they had brakes that acted like a pair of pliers that came to the side of the wheels. And those are what are most used nowadays. And they're pretty good. When I started biking, we had steel wheels and these brakes were good in dry weather, but in wet weather there was zero braking at all.

PALCA: Yeah.

Dr. WILSON: And I had my students--we actually developed a pretty good brake that worked on steel wheels. But anyhow, then they switched to aluminum wheels, and they worked better in wet weather. And they've gone through a number of what I think are silly brakes, like cantilever brakes and now V brakes which are snares and delusions in some respect, I mean, for all sorts of reasons. One is, if you're going down a steep hill--my wife and I did a tour in the Southern Alps of New Zealand when I was teaching there a few years ago. And on a tandem going steeply down a mountain road, the wheels can get so hot that you can melt the front tires. You can certainly melt the patches on your tubes.

PALCA: Hot from the friction of the brake cushion...

Dr. WILSON: Right.

PALCA: ...pad pressing against the rim, I guess.

Dr. WILSON: Exactly. Exactly. And so that's pretty dangerous.

PALCA: Yeah.

Dr. WILSON: And you can also get--rims will actually explode because these aluminum rims wear so fast that even if you get a little grit embedded in the rubber of your pads, then that acts as a machining device, and suddenly your wheel's under these pressures, sometimes they're 130 psi now in the tires--enormous forces outside. And so if your rim explodes when you're going downhill or even if you're in traffic and locks the front wheel, it's bad news. So...

PALCA: I don't like to hear this because bicycle is my main means of transportation, and I don't want to think about an exploding front wheel.

Dr. WILSON: I think it's horrible. You know, I think it's disgusting that--the reason why we can get away with bikes in this country is because 99.9 percent of bikes are bought in someplace by some enthusiast, and then he hangs it up. And you'll be lucky if the bike's done a hundred miles. And those of us who do thousands of miles a year, we're the ones that wear the rims off and get exploding wheels and rims, this, that and the other. And I think it's a big shame.

PALCA: Yeah. No, I was just told that--well, we have to finish about disc brakes because we started telling people about them...


PALCA: ...and we digressed.

Dr. WILSON: I'm sorry.

PALCA: So what is a disc brake?

Dr. WILSON: The disc brake--you see disc brakes on very modern bikes, especially mountain bikes. There's a little shiny disc that's down near the hub--it's about eight inches diameter. And it has, instead of having these plierlike things out on the outside of the wheel, they're attached to the fork, usually the left fork of the front that holds the front wheel and one of these tubes that come down to the center. And there's a little pad there that grips this disc pad. Now they're on also on--most modern cars have discs in the front and they have drum brakes in the back. And bikes have had drum brakes for a long while, but they've never been able to stop the bike properly. You know, we have them on our tandems nowadays for going downhill, and they're what's called drag brakes. I get my wife to put them on as hard as she can so that it heats up the middle of the wheel and not the outside.

PALCA: Got it.

All right. We're talking about bicycle science today. Our number is (800) 989-8255. And you're listening to TALK OF THE NATION from NPR News.

Ed Coyle, I was wondering, you know, you said that Lance Armstrong would come into the laboratory and you measured his power output and his oxygen consumption, things like that. But when you're measuring a cyclist's performance in the laboratory, that's not really the same--I mean, you don't get that wind resistance, for example, and you don't--I guess cooling is another thing that's hard to monitor. What do you lose when you study a cyclist indoors?

Prof. COYLE: Well, we do lose the aerodynamics and, you know, it's not important that the cyclist tuck down in an aerodynamic position or be on the drop handlebars. So we're really measuring his body's power output and not really how that interacts with the air.

PALCA: Right.

Prof. COYLE: So we are lacking, you know, the components that Dave was talking about, of the importance of the design of the bicycle in placing the rider in a very aerodynamic position. So that's the next step that is taken into the field.

PALCA: OK. Interesting.

Let's take another call now from Henry in Santa Cruz, California. Henry, welcome to the program.

HENRY (Caller): Hi.


HENRY: It's interesting that you just mentioned aerodynamics because in 1934, if I understand correctly, a second- or third-rate bicyclist ended up beating all the guys better than him because he was riding a recumbent bicycle, and they made them illegal. And nowadays, in--I think it was '89 from someone in Freedom, California, very close to Santa Cruz, a person was able to hit 65 mile an hour, Freddy Markham, and he became a--his bicycle ended up in the Smithsonian. Nowadays the record is around 80 miles an hour for a recumbent-style bicycle in the shell. And I'm wondering if you people have done any studies on recumbent bicycles, and could you kind of, like, help push them along, because people aren't buying them because they really don't know about them?

PALCA: Henry, interesting.

Ed Coyle, do you study people on ergometers in recumbent positions?

Prof. COYLE: No, we don't directly for competition. I mean, that is something that's being studied in patients who have spinal injuries and can't mount a regular bicycle, so they're exercising in the seated position. But again, they're not moving on the road. Their object is not speed, it's just getting a workout.

PALCA: Yeah.

Prof. COYLE: But it's been known for a long time, of course, that the recumbent bicycles can be very fast.

PALCA: And, David Wilson, I wonder, do you have any--you ride yourself in a recumbent, I think you said. Do they have an advantage apart from the riding position? Are they faster or does it--why do you choose a recumbent?

Dr. WILSON: Well, I started recumbent riding in '74 because I was worried about the people who went over the handlebars of regular bikes because--there were all kinds of reasons. Sometimes dogs ran into the wheel or they were carrying a raincoat that went into the wheel or various things can happen. And that's the worst accident you can have on a regular bike, I think, by yourself. Obviously, if you get run into by a Mack truck, it's not too good.

Let me just say something about what Ed just said about testing in a recumbent position. We used to think that you could get more power out of it because you just pushed with your backside into a seat, and you didn't have to use your hands and upper body to develop power. But people have done very careful tests, particular the MIT group that launched the Daedalus aircraft, the human-powered aircraft that did 119 kilometers from Crete to the isle of Santorini. And they were only very keen on choosing the method of pedaling that would give the maximum power. And they found it was exactly the same. They couldn't tell the difference between somebody riding in the recumbent position or the upright position. And they chose the recumbent because it does have less wind resistance and also because being relaxed in your upper body, the person could use both hands on the controls instead of having to pull himself down onto the saddle to push hard.

PALCA: All right. Well, I suppose most of us will never fly the Daedalus and most of us will never ride in the Tour de France, but at least we have some better idea of what it takes to do that. So thank you gentlemen, both, today for talking with us.

Dr. WILSON: Thank you.

Prof. COYLE: Thank you. You're welcome.

PALCA: Ed Coyle is a professor in the department of kinesiology and director of the Human Performance Laboratory at the University of Texas at Austin. David Gordon Wilson is professor emeritus at MIT's department of mechanical engineering and chief scientist at Wilson TurboPower. He's the author of "Bicycling Science," published by MIT Press.


PALCA: If have a comment or question for us, write to us at SCIENCE FRIDAY, 55 West 45th Street, Fourth Floor, New York, New York 10036. Internet address is Check out for more information and links to today's programs. You can listen to past editions of SCIENCE FRIDAY online or take them with you from the iTunes Music Store. And check out SCIENCE FRIDAY's Kids' Connection, free curricula materials for teaching science using SCIENCE FRIDAY. Just click on the `teachers' link on

From NPR News in Washington, I'm Joe Palca.

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