Breaking the Law of Averages, Part 3: Let it ride or let ‘er rip?

In the first two parts of this series we demonstrated how nature always takes away more than it intends to give back.

Going down a hill really fast does not make up for the time lost pedaling up.

Similarly, pedaling with the wind does not equalize pedaling into it. That is, of course, as long as we ride at constant power. The key difference between hills and winds is that on sufficiently long and steep descents you typically wind up going so fast that you have to hit the brakes, while you hardly ever find a tailwind that will cause you to go faster than what you’re comfortable with. So whereas you stop pedaling to go downhill, you still find yourself applying power to the pedals when the wind is at your back. Climbing is therefore a game of absolutes—effort going up and speed going down. Winds create situations with a little more range. You can choose how much to get on or off the gas.

The question is just how much.FASTER science of triathlon weight loss

Athletes with power meters will better appreciate this than those who don’t, but there’s still a lesson for everyone. If you don’t have a power meter, I’ll cut right to the chase so you can skip the wattage discussion—your time will improve if you push harder into the wind and relax when you go with it. The trick is knowing just how much harder you can push and how much to relax. If you’re gauging your bike performance according to a heart rate monitor and your cadence, I can’t really help you any further. For those with power meters, the details follow.

Let’s begin the discussion with a look at the wind conditions at a few well-known Ironman® courses. These are just a few top examples to show how the principles can be applied, but there are others. See if the conditions would be right for you to do a little strategic homework before your next race.

These four Ironman races either feature out-and-back bike courses or a loop with significant stretches that face headwinds and tailwinds (Wisconsin is almost a square). The data below show the average and maximum wind speeds for the race locations during the week they traditionally take place. The “prevailing direction” indicates the direction the wind blows from, so a “south” wind is actually blowing from south to north.*

Location                               Average               Max                   Prevailing Direction

Coeur d’Alene, Idaho     7mph                    13mph                    S, NE
Kona, Hawai’i                     8mph                    13mph                  S, SW
Tempe, Arizona                 5mph                    10mph                  E, W
Madison, Wisconsin        8mph                    14mph                  S, NW

Depending on the conditions, you can find yourself facing an almost perfect headwind / tailwind situation (if you could call headwinds “perfect”). Let’s analyze it from that perspective and bring back our hypothetical athlete from the previous discussion. He weighs about 145 pounds, has a good aero position on a high-end triathlon bike that weighs about 15 pounds, and can pedal a steady 230 watts. In a zero wind situation, he maintains a speed of 23.2.mph. When the winds blow at 8mph and he pedals at constant power, he goes 18.4mph into the wind and 28.6mph when it pushes him along. His average speed on an Ironman course would be 22.4mph, getting him through the bike in just less than 5 hours.

Now let’s say 230 watts is his critical power threshold for a 5-hour effort. Anyone who follows Joe Friel’s blog or has read Training and Racing with a Power Meter by Dr. Andrew Coggan knows that you can go over that threshold for a while if you find time elsewhere in your race to pedal below that level. Here’s the fork in the road. Let’s get our athlete to first take it easy pedaling into the wind, then when things are in his favor tell him to hammer it all the way back home.

Pedaling at 210 watts into the wind, then 250 watts with the tailwind
Speed into the headwind = 17.7mph                      Time to travel 56 miles = 3.16 hours
Speed with the tailwind = 29.37mph                       Time to travel 56 miles = 1.9 hours
Total time on the bike = 5 hours, 3 minutes          Average velocity = 22.1mph

Now let’s have him do it the other way (two Ironman bike courses in one day?!? Poor hypothetical cyclist!)

Pedaling at 250 watts into the wind, then 210 watts with the tailwind
Speed into the headwind = 19.13mph                    Time to travel 56 miles = 2.92 hours
Speed with the tailwind = 27.93mph                       Time to travel 56 miles = 2 hours
Total time on the bike = 4 hours, 55 minutes       Average velocity = 22.7mph

Our athlete who gives it a little more juice when the wind hits him gets home faster than both the “diesel” cyclist and the fair-weather hammerhead. When the going gets tough, the tough get going, and science bears out that being tough pays off in this situation.

Now comes a slight catch, and at this point I have to warn you that we’re getting into the graduate level of power meter usage. Some of you may have noticed that, because you go at different speeds against and with the wind, you do not hold the two corresponding power outputs for the same amount of time. This is bad, because we spend more time pedaling harder than 230 watts than we do pedaling under it, meaning that our average power requirement goes over what’s healthy for our athlete’s overall race performance. In other words, we pushed him too hard and risked blowing up on the run. We’re back to a dilemma of averages.

For those deeply fascinated with power, you probably already know that there’s a solution to this dilemma called normalized power. While programs like Golden Cheetah and Garmin Connect automatically calculate it from your ride data, it is possible to project what your normalized power would be on a ride based on hypothetical power values. The simulation is fairly easy to construct so long as you restrict the conditions to an out-and-back course and only consider direct headwinds and tailwinds. I’m currently working on developing a model that’s a little more versatile and would therefore be helpful to athletes in a wider range of real world conditions. I’ll post updates if the research produces something.

*Data from

If you’re interested in getting faster, you’ll be fascinated by FASTER: Demystifying the Science of Triathlon Speed. In Faster, astronautical engineer and triathlon journalist Jim Gourley explores the science of triathlon to see what truly makes you faster—and busts the myths and doublespeak that waste your money and slow down your racing. With this knowledge on your side, you can make simple changes that add up to free speed and faster racing.


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