In praise of Eddington numbers...

Sir Arthur Stanley Eddington OM FRS (28 December 1882 – 22 November 1944) was an English astronomer, physicist, mathematician, philosopher and populariser of science. The Eddington limit, the natural limit to the luminosity of stars, or the radiation generated by accretion onto a compact object, is named in his honour. So says Wikipedia, whence I have more or less directly lifted the preceding lines. He also wrote a number of articles that announced and explained Einstein's theory of general relativity to the English-speaking world, and the Eddington number is named for him, being the number of protons in the observable universe.

All very interesting, but what do he and the numbers that bear his name have to do with cycling?

Well, Eddington is also credited with devising the other Eddington number, a measure of a cyclist's long-distance riding achievements. An Eddington number in the context of cycling, as opposed to astrophysics, is defined as the maximum number E such that the cyclist has cycled at least E miles on at least E days. It can be calculated over any period, and also over a cyclist's lifetime. Wikipedia goes on to explain that "an Eddington number of 70 would imply that the cyclist has cycled at least 70 miles in a day on at least 70 occasions. Achieving a high Eddington number is difficult, since moving from, say, 70 to 75 will (probably) require more than five new long-distance rides, since any rides shorter than 75 miles will no longer be included in the reckoning." In other words, the reason you'd probably need more than five rides to go from 70 to 75 is that some of the rides that got you above 70 may not already be above 75. Got that? The net consequence of all this is that improving your Eddington number gets progressively harder and harder...

But it's also exactly the performance measure I need. As someone whose work and life mean I do a lot of quite short rides, trying to increasing my average ride length is a depressingly futile exercise. But increasing my E number... that's do-able, I think. Not least because it is concerned with the miles ridden in a day, rather than the length of individual rides. In other words, if I ride four miles each way to work and back in a day that counts as eight miles towards my E number. Happy days.

The flip side of this "distance in a day, not distance in a ride" stipulation is that E numbers can be quite hard to calculate. I first saw it being offered on VeloViewer, and this website also offers to calculate it for you, based on your Strava activities. Me, I've already got my own Strava analysis tool, built using Google Sheets automation and the Strava API, so with a bit of trial and error I was able to add E number calculation into that. Eddington's own life-time E-number was 84. Mine, so far, is 40 ... but I'm not dead yet.

Pictured: Sir Arthur Eddington - physicist and cycling nerd. Not pictured: the man's bike...