このチャートの平均速度は25km/hから40km/h以上になっていますが、これは大きな変化です。他の人も言っていますが、平均速度を上げるためにはペダルにかかるパワーを非線形に上げる必要があります。優勝者の平均速度に合わせるために必要なワット数は以下の通りです(あくまでも粗雑な近似値です)。
60ワットから240ワットへの変更は非常に大きな変化です。例えば、より空気力学的な自転車は、与えられた平均速度に必要なパワーを減少させ、坂道を上るときに軽い自転車と同じです。このグラフがどれだけ不正確なものであっても、私の指摘は有効であるべきですが、ここに私がグラフを生成するために使用した厄介なスクリプトがあります
これは、CSVにエクスポートされた ここ のデータを使用しています( このドキュメント から)
平均速度と必要ワット数の計算は非常に単純化されていますが、私にとっては 私の答えはここ からスクリプトを修正するだけで簡単でした!
#!/usr/bin/env python2
"""Wattage required to match pace of TdF over the years
Written in Python 2.7
"""
def Cd(desc):
"""Coefficient of drag
Coefficient of drag is a dimensionless number that relates an
objects drag force to its area and speed
"""
values = {
"tops": 1.15, # Source: "Bicycling Science" (Wilson, 2004)
"hoods": 1.0, # Source: "Bicycling Science" (Wilson, 2004)
"drops": 0.88, # Source: "The effect of crosswinds upon time trials" (Kyle,1991)
"aerobars": 0.70, # Source: "The effect of crosswinds upon time trials" (Kyle,1991)
}
return values[desc]
def A(desc):
"""Frontal area is typically measured in metres squared. A
typical cyclist presents a frontal area of 0.3 to 0.6 metres
squared depending on position. Frontal areas of an average
cyclist riding in different positions are as follows
http://www.cyclingpowermodels.com/CyclingAerodynamics.aspx
"""
values = {'tops': 0.632, 'hoods': 0.40, 'drops': 0.32}
return values[desc]
def airdensity(temp):
"""Air density in kg/m3
Values are at sea-level (I think..?)
Values from changing temperature on:
http://www.wolframalpha.com/input/?i=%28air+density+at+40%C2%B0C%29
Could calculate this:
http://en.wikipedia.org/wiki/Density_of_air
"""
values = {
0: 1.293,
10: 1.247,
20: 1.204,
30: 1.164,
40: 1.127,
}
return values[temp]
"""
F = CdA p [v^2/2]
where:
F = Aerodynamic drag force in Newtons.
p = Air density in kg/m3 (typically 1.225kg in the "standard atmosphere" at sea level)
v = Velocity (metres/second). Let's say 10.28 which is 23mph
"""
def required_wattage(speed_m_s):
"""What wattage will the mathematicallytheoretical cyclist need to
output to travel at a specific speed?
"""
position = "drops"
temp = 20 # celcius
F = Cd(position) * A(position) * airdensity(temp) * ((speed_m_s**2)/2)
watts = speed_m_s*F
return watts
#print "To travel at %sm/s in %s*C requires %.02f watts" % (v, temp, watts)
def get_stages(f):
import csv
reader = csv.reader(f)
headings = next(reader)
for row in reader:
info = dict(zip(headings, row))
yield info
if __name__ == ' __main__':
years, watts = [], []
import sys
# tdf_winners.csv downloaded from
# http://www.guardian.co.uk/news/datablog/2012/jul/23/tour-de-france-winner-list-garin-wiggins
for stage in get_stages(open("tdf_winners.csv")):
speed_km_h = float(stage['Average km/h'])
dist_km = int(stage['Course distance, km'].replace(",", ""))
dist_m = dist_km * 1000
speed_m_s = (speed_km_h * 1000)/(60*60)
watts_req = required_wattage(speed_m_s)
years.append(stage['Year'])
watts.append(watts_req)
#print "%s,%.0f" % (stage['Year'], watts_req)
print "year = c(%s)" % (", ".join(str(x) for x in years))
print "watts = c(%s)" % (", ".join(str(x) for x in watts))
print """plot(x=years, y=watts, type='l', xlab="Year of TdF", ylab="Average watts required", ylim=c(0, 250))"""