>Bier used McLaughlin’s record-setting rides for his analysis. The route McLaughlin used is an 810-meter segment of road with a 117-meter climb. There wasn’t very much wind for McLaughlin’s first attempt in 2020, but on his second 2021 ride, he had a tailwind of about 12 mph (or 5.4 m/s). Given the marked improvement in his time, there was much “qualitative speculation” in cycling circles about the degree to which the tailwind helped set that “everesting” record, with some pondering whether the rules might need to be changed to limit allowed wind speeds for determining future everesting records.
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>Bier points out in his paper that the same tailwind would have been a headwind on McLaughlin’s descent; the question, therefore, is whether the strong tailwind effect on climbs was greater than the headwind on descents. There is a concept known as “the bicyclist’s paradox” in physics education circles: if one bikes up a hill and back down, and there is no net change in elevation, one might intuitively expect that the uphill and downhill speeds should cancel out.
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>But that’s not what happens, largely because of air resistance. Granted, air resistance is a negligible factor when cycling uphill, which is why experienced bicyclists will try to double their power output/speed during climbs. However, the force of air friction one is fighting increases with the square of one’s speed. One needs four times the force to double one’s speed and nine times as much to triple one’s speed. This, says Bier, “wreaks havoc.”
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>Bier found that while a tailwind might help a little during climbs, the headwind actually has a huge effect during downhill stretches. In fact, going downhill adds about 12 seconds to the lap time because “it takes time to accelerate to the terminal speed.” One might improve one’s everesting time by riding longer laps. For example, if one everested on a hill twice as long as McLaughlin’s Mamore Gap route, one would only make 30 downhill accelerations instead of 76, adding a little over seven minutes to the time. He described the added 12 seconds as simply “the price one pays for a shorter lap.”
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>…
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>That said, “All in all, changing the everesting rules to set limits on allowed wind speeds is not warranted by the physics,” Bier concluded. “What the control analysis ultimately tells us is that the most intuitive ways towards faster everesting times, i.e., reducing weight and increasing power, are indeed the most effective ways. There are no clever tricks to get around the necessary diet and exercise.”
>Among cycling enthusiasts the word “everest” has also become a verb over the last few years. “To everest” means going up and down the same hill or mountain until the elevation of Mount Everest (8848 m) has been accumulated in the course of the repeated ascents. It has been suggested that considerable advantage can be obtained by having a strong tailwind on the climbs. We make a quantitative assessment and show that the effect of a tailwind is small. Using control coefficients, we furthermore assess how factors such as weight reduction, increased power output, and improved aerodynamics can enhance the performance.
brickyardjimmy on
Ok. But headwinds don’t help worse.
rich1051414 on
If you don’t understand the title, basically, it is better to have a tailwind when going downhill than uphill.
le66669 on
Did they show that a square law effect has less of an effect at a lower value than at a higher value?
Anustart15 on
The real secret would be to find an exposed ascent with a well-shielded descent and then do that in a tailwind on the ascent, but where you are protected from the headwind on the way down.
5 Comments
Article highlights:
>Bier used McLaughlin’s record-setting rides for his analysis. The route McLaughlin used is an 810-meter segment of road with a 117-meter climb. There wasn’t very much wind for McLaughlin’s first attempt in 2020, but on his second 2021 ride, he had a tailwind of about 12 mph (or 5.4 m/s). Given the marked improvement in his time, there was much “qualitative speculation” in cycling circles about the degree to which the tailwind helped set that “everesting” record, with some pondering whether the rules might need to be changed to limit allowed wind speeds for determining future everesting records.
>
>Bier points out in his paper that the same tailwind would have been a headwind on McLaughlin’s descent; the question, therefore, is whether the strong tailwind effect on climbs was greater than the headwind on descents. There is a concept known as “the bicyclist’s paradox” in physics education circles: if one bikes up a hill and back down, and there is no net change in elevation, one might intuitively expect that the uphill and downhill speeds should cancel out.
>
>But that’s not what happens, largely because of air resistance. Granted, air resistance is a negligible factor when cycling uphill, which is why experienced bicyclists will try to double their power output/speed during climbs. However, the force of air friction one is fighting increases with the square of one’s speed. One needs four times the force to double one’s speed and nine times as much to triple one’s speed. This, says Bier, “wreaks havoc.”
>
>Bier found that while a tailwind might help a little during climbs, the headwind actually has a huge effect during downhill stretches. In fact, going downhill adds about 12 seconds to the lap time because “it takes time to accelerate to the terminal speed.” One might improve one’s everesting time by riding longer laps. For example, if one everested on a hill twice as long as McLaughlin’s Mamore Gap route, one would only make 30 downhill accelerations instead of 76, adding a little over seven minutes to the time. He described the added 12 seconds as simply “the price one pays for a shorter lap.”
>
>…
>
>That said, “All in all, changing the everesting rules to set limits on allowed wind speeds is not warranted by the physics,” Bier concluded. “What the control analysis ultimately tells us is that the most intuitive ways towards faster everesting times, i.e., reducing weight and increasing power, are indeed the most effective ways. There are no clever tricks to get around the necessary diet and exercise.”
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Research paper link: [The physics of “everesting” on a bicycle](https://pubs.aip.org/aapt/ajp/article/92/10/737/3312282/The-physics-of-everesting-on-a-bicycle)
Abstract:
>Among cycling enthusiasts the word “everest” has also become a verb over the last few years. “To everest” means going up and down the same hill or mountain until the elevation of Mount Everest (8848 m) has been accumulated in the course of the repeated ascents. It has been suggested that considerable advantage can be obtained by having a strong tailwind on the climbs. We make a quantitative assessment and show that the effect of a tailwind is small. Using control coefficients, we furthermore assess how factors such as weight reduction, increased power output, and improved aerodynamics can enhance the performance.
Ok. But headwinds don’t help worse.
If you don’t understand the title, basically, it is better to have a tailwind when going downhill than uphill.
Did they show that a square law effect has less of an effect at a lower value than at a higher value?
The real secret would be to find an exposed ascent with a well-shielded descent and then do that in a tailwind on the ascent, but where you are protected from the headwind on the way down.