Performance Index – how is it calculated and how can I use it?

26 August 2016

The Performance Index (PI) is a tool for those who have access to a power meter which simplifies the way in which individuals can analyse their performance. It does this by breaking the rider’s cycling results over time into eight key performance areas, factoring in the rider’s weight to calculate a score. The scores in each of these areas are then combined into a single overall performance number, referred to as the Performance Index, on a scale zero to 1000.

The peloton on stage four of the 2015 Tour of Oman

Below are the peak power durations that are taken into account for each performance area:

  • Peak: 3 second power
  • Sprint: 10 second power
  • Long sprint: 30 second power
  • Lactate: tolerance: 1 minute power
  • Maximum aerobic power: 3 minute power
  • Sustained aerobic power: 6 minute power
  • Short endurance: 15 minute power
  • Long endurance: 40 minute power

As you may have guessed from above, the formula is heavily reliant upon an athlete’s peak power values, and in particular how often they are hitting these peak power values for each time duration. Therefore if an athlete is not hitting these peak power values their PI will begin to decline, even if overall training load (as measured by CTL for example) is increasing.

Yellow symbols representing improved peak powers across a wide range of power durations

If you want to drill into individual ride data in great detail we have other tools that are better suited such as our ride graph or heart rate/power graphs. PI is a tool to monitor your overall performance over time. If you are hitting higher peak powers your performance metric will show this with your PI increasing. You can then view the eight different performance areas and see where your strengths and weaknesses lie and work on improving those weaknesses.

Performance Index Ratio