There has been a discussion about how to take account of “inaccessible squares” in the max square challenge ( https://www.strava.com/clubs/279168/posts/582450 ).
Here is what I wrote so far on this. Plan to expand this with more examples of the clump idea.
“I agree with Nils that it raises the prospect of endless debate about what counts as inaccessible. E.g. someone on Facebook already posed the question about dual carriageways – certainly many people don’t like riding on them for good reasons, but they are not inaccessible. It just adds extra motivation for a 4am Sunday ride.
“Similarly there are very-hard-to-visit places – power stations, large factories, some military areas. I have the germ of an idea that we could set up something like the Association of British Tile Cyclists (or something similar grand, or indeed for Belgium). This could be an “official” entity that can make access requests which may be more successful than individual requests. It would also be an way of setting up occasional group rides which have a stated goal of tiling a particular area (so frustrating when you do a sportive that misses a few out in the middle…. 🙂 )”
“Having said all that, there are going to be areas where even the most determined can’t get to – there are military areas where even the military don’t go – e.g. firing ranges of certain types have a build up of unexploded unordances. You’re not going there, even on an open day. So, the idea of some sort of different metric does have some appeal. But those proposed on Facebook, e.g. “98% of 40×40″, are also unsatisfying. It is difficult to have a leaderboard comparing 100% of 38×38 versus 98% of 40×40. And we all like a leaderboard :-)”
“So I’ve been fumbling around for an alternate metric. Of course one possibility is just “total tiles” as already reported by VeloViewer. Another possibility, is to define a “clump”. A square is in your clump if you been to that square and to three of the four adjacent squares. Then measure how many squares are in your clump. This clump measure rewards people like Phill and Eric who have been to huge swathes of their area, but which aren’t square-shaped. It is also quite robust against a single hole due to an inccessible. But it is doesn’t reward a single track of squares. E.g. if you just cycled from London to Paris you clump size would be near zero as all you have is a long streaky path – you haven’t been “everywhere” in that area.