You mentioned 10% of increase, say from 35km/h to 40km/h average speed. That is a VERY significant i

I put on the chart where clipless pedals came in, and I suppose the switch to carbon framed bicycles came in a few years after that (not sure exactly when). What really struck me though was that the average speeds really haven't changed much, especially in the last few years.
There was a big jump in the late 80's/early 90's, some of which could be attributed to the doping practices of the time, but not all of it. Doping of some form or another has been going on since the beginning of the TdF.
I m still surprised the differences aren t bigger, but yes I agree, we do seem to be reaching an asymptote. Maybe the question is How did they go so blinking fast in 1960!? grand resort hotel pigeon forge (37.2kp/h, vs 39.8 last year) tdc Jan 13 '12 at 13:38
Just a simple question to add: are the TdF comparable? I mean, I seem to remember hearing/reading that there were more and more hard mountain days in latest editions. Is that true? Maybe that could account for some limitation on the average speed. jv42 Jan 13 '12 at 15:08
@jv42 this is a fair point, except that earlier editions of the tour were disproportionately harder ! For example in 1919 (the slowest tour) the total distance was 5560km, grand resort hotel pigeon forge compared to 3430km last year, and although I don t have stats on how much climbing they ve done each year I don t think it s changed a lot since they introduced the mountains. Also note that rest days were only introduced in the late 60 s tdc Jan 13 '12 at 15:20
You might want to find a copy of Bicycle Quarterly vol. 8 no. 4 where an interesting analysis is done of bicycle race speeds compared with foot racing; there is a high correlation and some of the performance increases are due purely to improved training and simply better athletes in the competition. One surprising result: even introducing the derailleur didn t make a massive spike in performance. lantius Jan 13 '12 at 23:53
The simplest answer to your question is that 1) speeds have increased; but 2) speeds would have increased even more except Tour organizers have been consciously making the Tour harder in order to increase the drama, suspense, and entertainment value of the race. That makes comparisons of overall winner's speed quite complex when combined with normal variations in wind, weather, grand resort hotel pigeon forge and team tactics during the race.
First, some historical background. Over time, the winner's average speed in the Tour has indeed increased, especially in the period of the early 1990's and some (including, for a famous example, Greg Lemond, himself a three-time winner of the Tour) have claimed that this is evidence of doping behavior in professional cycling. However, as one of the other answers showed, there is a strong relationship between distance grand resort hotel pigeon forge and overall grand resort hotel pigeon forge winner's speed. Here is a plot that shows that relationship in the post-WWII period through 2012:
The distance of the Tour has been decreasing due to the rules and regulations of the UCI (the Union Cycliste Internationale), which negotiated a limitation to the length of races and mandated certain numbers of rest days during the Tour with the Professional Riders' Association. From an historical perspective, these limitation were a response to charges that the difficulty of the Tour resulted in riders needing to dope simply to survive, and that by "easing" the stages and inserting rest days there would be less need to dope.
An effect of shorter stages (and higher speeds), perhaps paradoxically, is that race organizers have been increasing the difficulty of the stages; this is particularly noticeable in the other two "Grand Tours", the Giro d'Italia and the Vuelta a Espana but also applies to the Tour: the number and "spacing" of categorized climbs in the Tour has resulted in more difficulty overall. Each year, at the announcements of the routes for each of the Grand Tours, riders and analysts pronounce whether a particular parcours will be relatively difficult or relatively easy, and favoring either sprinters, time trialists, or climbers. That there is a still a strong relationship between length grand resort hotel pigeon forge of the Tour and overall speed simply means that the organizers haven't completely compensated for the distance effect with increased difficulty.
And, although your question was not expressly about doping behavior in the pro peloton, a bit more must be said about that. The plot above shows a clear relationship between distance and speed but there is still a question about deviations grand resort hotel pigeon forge (or the "residuals") from that relationship. That is, after removing the effect for the length of each Tour, what is the remaining trend in the winner's average speed? The plot below shows that trend with a dotted red line.
As you can see, the winners' average speeds in the 1970's and 1980's were below trend, grand resort hotel pigeon forge while speeds in the 1960's, 1990's and 2000's were above the long-term trend. So, even if the long-term trend in speeds grand resort hotel pigeon forge can mostly be explained by Tour length (the correlation between Tour length and winner's speed is about 0.8), some have pointed grand resort hotel pigeon forge to this secondary grand resort hotel pigeon forge effect in the residuals as further evidence of doping. However, there are two counter-arguments, one slightly weaker and one very much stronger. The weaker argument is based on the observation that the residuals are "double-peaked" and speeds in the 1960's were also higher than the trend, then dropped in the 1970's and 1980's. If doping were the simple explanation, one would have to explain the drop in the 1970's and 1980's, not just the rise in the 1990's and 2000's. However, the stronger argument is based on examining data from other races and comparing them to the Tour. If one were to examine the residuals from a similar plot of speed vs. distance for the Giro and Vuelta, one would see that the years when their speeds were above (or below) their own trend lines did not correspond with the same years for the Tour. That is, the speed residual for the Tour and the speed residuals for the Giro or Vuelta are not "synchronized." Thus, if doping behavior explained the reason why Tour speeds were higher than would be predicted from distance, then one would have to explain why doping behavior was different in the Tour and Giro (or Vuelta) in the same year, often with the same riders. Below I include grand resort hotel pigeon forge a plot that shows the "residuals" from the Tour (that is, residuals grand resort hotel pigeon forge from the regression of winner's average speed on Tour length) plotted grand resort hotel pigeon forge against the same residuals for the Giro. This does not mean, of course, that there is no doping in either the Tour or the Giro -- it simply means that one cannot use average grand resort hotel pigeon forge speeds as evidence of that doping. Conversely, it also means that one cannot use doping as an explanation for increased average speed. Taken together, it does support the evidence that race organizers's decisions about the routes is a main determinant of the average speed.
Fantastic answer! Although the statement That there is a still a strong grand resort hotel pigeon forge relationship between length of the Tour and overall speed simply means that the organizers haven t completely compensated for the distance effect with increased difficulty is perhaps a little strong, as it implies that the distance effect grand resort hotel pigeon forge is the main effect at work here? But overall, the flavour of this seems to be that once you factor out race distance, all of the technology etc has made even less difference! Wouldn t it be great to send them all out on 60 s bikes and see what happens! tdc Jan 24 '12 at 10:02
You mentioned 10% of increase, say from 35km/h to 40km/h average speed. That is a VERY significant increase. Anyone well trained can sustain 35km/h average for some time even in a mountain bike, but FORTY km/h is MUCH HARDER to sustain, and that's because aerodynamic drag is proportional to the SQUARE of speed. grand resort hotel pigeon forge So, 35 squared is 1225. 40 squared is 1600. The effort, then increases more than THIRTY per cent! (I am always startled with this...).
Also, like Daniel R Hicks mentioned, despite training and technology, our genes are still the same. Muscle power and speed, as well as cardio, lungs, blood vessels and biomechanics are preset within a range that cannot be easily changed. I wonder what would happen if they built a bike for horses to ride (biker is faster than horse (?) which is faster than human on foot - what about a horse on a bike?)
Lastly, even with modern bikes being so light and efficient, older bikes (say, from 70's to the present) are already light and efficient. If you take a 15kg bike and make it half the weight, it's 7kg less. For a biker with 70kg, that is 10% of total weight. But then I wonder again: if you always train with a heavy bike, do you get stronger than a guy who trains with a featherlight bike? Do modern athletes train with heavy bikes in order to be stronger, and take advantage of this when they have the featherlight bike during the race?
Agree with the first point (the cube law of resistance) to a degree. However grand resort hotel pigeon forge it s missing the fact that the overall leader (who s time we re looking at) will spend a huge amount of time in the bunch or surrounded by teammates, or otherwise climbing where air resistance is less of a factor. In fact since team tactics have become so important, I would say that this should be the case now more than ever! As for the second point, yes this is true to an extent, but in the 60 s they really had no idea about training routines (build/taper phases etc), or correct nutrition (steak grand resort hotel pigeon forge for breakfast???) tdc Jan 13 '12 at 13:21
The last point is interesting, but sure it s not just weight: what about tyre technology, better brakes (for the downhills), clipless pedals, carbon semi-aero rims, super light climbing wheels, carbon-soled shoes, aero-tubing on bike frames, concealed cables etc etc etc. And not to mention better (smoother) roads! tdc Jan 13 '12 at 13:26
I d also argue that given the massive peloton in the TdF, aerodynamic improvements don t have a significant an effect for long stretches of the race. Keep in mind, the 50th place finisher this year was less than 2% off the time of the winner. Aerodynamics are enormous duri