I recently came across an interesting cycling metric known as the Eddington Number, a number devised to measure a cyclist’s long-distance riding achievements.

Devised by English physicist Sir Arthur Stanley Eddington, the Eddington Number is defined as the maximum number E such that the cyclist has cycled E kilometres (or miles) on E days. For example, an Eddington Number of 50 would imply that the cyclist has cycled at least 50 kilometres (or miles) in a day on 50 occasions.

Achieving a high Eddington Number is difficult since moving from 50 to 55, for example, will probably require more that five new long distance rides since any rides shorted than 55 kilometres will no longer be included in the reckoning. This is why the concept of the Eddington Number is particularly suited to endurance cycling as it highlights consistency as well as distance.

It turns out that HealthFit, the app that I use to maintain and backup all of my exercise data includes an Eddington Number calculation. At the time of writing my number is 43 (kilometres) - I only need another two 44 kilometre rides to get this up to 44.

I’ll be honest, until I considered nuance of how it is calculated I thought my number would be higher. It may very well be - HealthFit only contains data from when I started wearing an Apple Watch, and I have a Strava history that goes back almost 10 years before that (during which I cycled from Land’s End to John o’Groats). Whilst I’m sure tools already exist for this, I’m thinking of building a little web app to connect to the Strava API to calculate my ‘true’ Eddington Number. It will be an interesting little exercise, so I might write it up here.