Race strategy for a gran fondo: where to spend your watts

The short answer: on a hilly or windy course, the same average power gets you to the finish sooner if you ride a little harder uphill and into the wind, and a little easier downhill and with the wind. In models of time trials that was worth between half a minute and two minutes, more for slower riders. The limit is what your body tolerates, so vary by about 10%, not more.

Why even power is not the fastest

You spend more time on the slow parts of a course than on the fast ones. A watt added on a climb or into a headwind, where you are slow, buys more time than a watt saved on a descent or with a tailwind costs you. On a descent much of your power goes into air resistance, which grows steeply with speed, so extra watts there buy very little.

A model of a 10 km time trial with alternating 1 km climbs and descents at 10% found that varying effort by 10% with the terrain, at the same average, was 1 minute 33 seconds faster than riding evenly. On a 40 km course with alternating headwind and tailwind at 16 km/h, it was 29 seconds faster ¹.

A newer model with validated coefficients found slightly larger gains. At 289 watts average, varying power by ±10% saved 126 seconds on the hilly course and 51 seconds on the windy one, and even 26 seconds on an ordinary 40 km time trial. The riders with the lowest average power gained the most ².

What this means on a fondo

• Climbs and headwind: a little above your average. That is where time is won.
• Descents and tailwind: below your average. Pedal while it still adds speed, then tuck and recover. Your position matters more than your watts there; see Descending.
• Keep the variation modest. Both models used about 10%. How much variation a rider can sustain over a race is still unclear, the authors say ². Riding 30% over your average on the first climb is not this strategy; it is how a long day goes wrong.
• Ride in a group where you can. In a big group you push a fraction of the air you would alone, which changes the sums more than any pacing plan; see Riding in a group.
• Fuel to the plan. Harder sections burn more carbohydrate. A plan only works if you eat and drink enough to finish it; see How many carbs per hour.

Know your course before you start

Pacing for the wind needs to know where the wind will be. The forecast for the start town at seven o’clock does not tell you that the long valley after the second climb will be straight into a headwind at eleven. Race weather does: it shows the wind against the road for every stretch of your course, at the time you get there.