I've just heard about an interesting concept/challenge: the Eddington number. Quoting the formal definition: "This criterion was the largest integer n such that one had cycled at least n miles on n different days." I think it's easier to understand it by examples:
* To get a number of 10, you need to have cycled 10 miles at least 10 times in your life.
* To get a number of 20, you need to have cycled 20 miles at least 20 times in your life.
Since I've already got the figures available, it didn't take me long to sort out a new set of formulae for this.
Based on that, my current number is 26, and I'm fairly close to 27: I just need to do 2 more days where I cycle 44 km (27 miles). The furthest I've ever gone in a single day is 142 km (88 miles), so I have "partial credit" for all the Eddington numbers up to 88.
I've only been tracking my daily distance since mid-2009, but that doesn't really matter. Any short distances (less than 25 miles) are irrelevant, because I've already hit that target, and I don't recall doing many (if any) longer days in my youth. Now that the Excel file is set up, I don't need to do anything extra on a daily basis: I just need to add a new column once a year (a very quick job), then it will keep itself up to date.
The main point of the Eddington number seems to be that it rewards consistency: someone who cycles a short distance on their daily commute every day would get a higher score than someone who does the London to Brighton bike ride once a year and then leaves their bike in the shed for the rest of the year. So, it's a nice little incentive to keep cycling all year round, even when the weather gets a bit colder.