The math behind a time trial: A nerdy preview of the Giro d’Italia stage 7 time trial

How do you optimise for a Grand Tour time trial? The 2024 Giro d’Italia time trial course with 420 metres elevation gain is the perfect arena to delve into some time trial performance geekery. Our first challenge is to optimise our time with a cunning pacing strategy; then we’ll discover if a bike swap will be faster for the pros on Friday; and finally, will the stage be a day for a powerhouse like Filippo Ganna or a climber such as Tadej Pogačar?

The interesting aspect of the 40.8km Giro time trial course is where the elevation gain is. The first 33km are comparatively flat. If the course was to end at kilometre 33, your best bet is to simply try to hold your highest sustainable power from Foligno to Ponte San Giovanni. However, our final destination is Perugia a further 7km uphill, with gradients peaking at 16%.

Below are two elevation charts. The first is the traditional elevation chart, with distance along the X-axis. The second chart shows a simulation time along the X-axis, revealing the significance of that final 7 km on the course.

Now to our challenge, optimising our power output for this course. Imagine we are a pro cyclist competing in the Giro d’Italia individual time trial. Our target power for the individual time trial is around 400 watts (~1300Kj). We choose to assign a conservative 20Kj additional ‘budget’ to optimise power strategy. I’ll explain why a budget would be decided this way shortly.