How much time does extra weight cost on Alpe d’Huez?
Stumble it!Ever wondered how much difference it would make if you made your bike lighter? I guess most serious riders once in while have concerns about their bikes whether they are light enough. As previously described the bike weight has impact on performance – especially during climbing. Thus, I thought it was interesting to find out how much difference it makes if you ride a heavier bike up alpe d’Huez. This little trial was performed by the best rider I coach as a part of his preparation for Tour de l’avenir (U23 Tour de France) in September.
In this experiment he had to ride up Alpe d’Huez four times with different setups. He was supposed to keep a pace around 275w on all four rides. The test bike was a Pinarello Prince equipped with Shimano Dura Ace and SRM crank:
1. Normal bike + 1.8L extra water in tyres(!)
This setup was quite interesting and got quite a lot of attention the day before when he had a puncture..! It was possible to fill 900ml into each tyre. Reducing weights on wheels is more important than reducing weight on non-rolling equipment e.g. bike saddle.
2. Normal bike + 1,8L extra water on bike.
This setup also got some serious attention because he rode a relative fast pace compared to most riders visiting Alpe d’Huez. Thus, when he performed the trial, well-trained riders were trying to keep up with his pace because this setup looked so extreme.
3. Normal bike
This setup was a completely normal bike.
4. Normal bike, reduced tyre pressure only 3 bars.
The last setup was ridden with reduced tyre pressure to 3bars. This was a tough finish on the last ride up Alpe d’Huez this day.
Results:
1. 52.01, 275w
2. 51.34, 277w
3. 49.40, 278w
4. 50.38, 273w
1,8L extra weight costs 1.54min up Alpe d’Huez. This is a remarkable test that shows us how important weight savings are when you are riding on steep hills. Also it shows that weight savings on wheels might be more important than weight saving on non-rolling equipment. These trials were only possible because of his SRM Crank that made it possible to compare each ride up the hill. You can make similar trials to test your bike setup if you want to optimize your bike equipment. These tests can be extremely helpful for e.g. time trialists if you don’t have wind tunnel in the neighbourhood.
How did he get the tires filled with water? I tried that with a football once, and it wasn’t easy to do. He didn’t descend with water in his tires, did he?
I told him to not do that because it sounded a bit risky. He didn’t bring a pump to the top, so he did the downhill with tyres full of water…
interesting but i’m not sure that you can make the conclusion that wheel mass is worse than frame mass.
Although the SRM allowed the rider to keep the power levels similar there are slight differences. In order to draw conclusions some normalisation has to be done.
Taking the normal run (#3) as the bench mark and assuming the 278w is the average for the climb, the total energy used for the climb is 828440J.
Using the same method, the total energy used for each climb is as follows:
1. 858275j
2. 857038j
3. 828440j
4. 829374j
The difference between the heavy wheel and heavy frame (#1 & #2) runs is about 0.15% in total energy required. This is in the range of the typical measurement error. This implies that if the rider put out the same power for each set up the time would be the same.
The difference between the normal climb and the flat tire climb (#3 & #4) is also around 0.11%
From the above numbers I would conclude that it doesn’t matter where the weight is located (rotating vs non-rotating).
Of course to get really solid results the climbs would have to repeated several times (not popular with the rider!)
beebee>>
Thanks for commenting. You’re right, we will need (a lot) more riders to make these results statistical significant. Also there is a couple of other concerns like the weather and the rider’s body weight troughout the day. It is certainly non-scientific, but still, I like the setup and think other riders should try similar things with their power meter mounted.
These results shall be seen as an example of how you can make your own field studies using a power meter. Conclusions shall be made with the above comments in mind.
Jesper
Ps. The rider who performed this workout finished 26th overall in Tour de l’Avenir yesterday.
[...] Tour de l’Avenir 2008. Only 60 riders finished this race due to a very tough course. I wonder if the Tour de France society will implement some of stage finishes from this course, because these finishes made the race a lot more spectacular than the real Tour de France. Read about one of my riders training sessions before Tour de l’Avenir. [...]
[...] a role for your overall performance. You might have read about my little experiment to find out how much does extra weight cost on Alpe d’Huez which shows that even small weight savings makes a difference. Thus, it is worth considering bike [...]