Another Day, Another Set of Wheels

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With two weeks of hard racing in their legs already, most of the riders in the 2004 Tour de France were content to take it relatively easy today. To help further reduce the work they had to do during Stage 14, riders chose different equipment than they used yesterday in the big mountains.

The most common difference between the equipment used in the mountains and on flat stages is in the wheels. For a stage like today, semi-aerodynamic wheels with deep rims and bladed spokes were a good choice. These wheels are heavier than the wheels used in the mountains, but lighter than the three- and four-spoked carbon wheels used in time trials. Semi-aero wheels are also easier to control than time trial wheels in crosswinds.

Semi-aero wheels significantly reduce the aerodynamic drag that slows riders down, meaning they can either go faster with the same amount of work, or go the same speed as before while doing less work. Whichever way you look at it, these wheels are the right choice for fast and flat stages, especially because the aerodynamic advantage increases as speeds go up.

In the mountains, weight takes precedence over aerodynamics. Aerodynamic bikes and wheels tend to be relatively heavy, and riders don’t want to lift any additional weight against gravity. The UCI set the minimum allowable weight of a bicycle at 6.8 kilograms (15 lbs), and the bike Lance Armstrong rode to his Stage 13 victory was just 7.1 kilograms (15.6 lbs). Cutting the total weight of the bicycle can save you between 5-30 seconds per kilometer going uphill. When the grade is shallow, the time saved is at the small end of the scale, but as the climb gets steeper, the influence of weight increases.

During today’s flat stage along the Mediterranean coast, equipment wasn’t the only way to make the ride a little easier. Riding with your hands in the drops of your handlebars significantly reduces the frontal area you expose to the wind. By reducing the size of the hole you have to punch through the air, you can go faster without increasing your power output. Of course, the aerodynamic advantage of riding in the drops has to be balanced with your ability to stay in that position comfortably for long periods of time; and Tour riders tend to be quite flexible enough to ride in the drops for a long time.

With a rest day tomorrow and the first stage in the Alps following that, the next time we see the riders in the Tour de France, they will have changed their equipment once again in favor of the lightweight climbing bikes and wheels.