I was thinking in the context of Audax rules that you can't use a circular route repeatedly e.g. to make up 200km by repetition. You can reverse a loop, I believe. So to avoid repeating loops you'd need multiple largely non-overlapping loops. For instance a figure 8 or a cloverleaf. Like the events from the 'uts near Ugley.
Indeed, I think the "rule" is something along the lines of:
"You should not use the same stretch of road in the same direction unnecessarily."
So the 'Uts rides don't have much of a choice as there are only 3 main routes away from the 'Uts, but they diverge as soon as they get a chance. (And none of them have ever used that loop round through Little Henham I don't think, at least looking at Veloviewer I've never ridden that bit, maybe I'll divert round there next time I'm up there.)
I reckon I could come up with a 200km route that fits within a 10 mile radius of here without trying too hard, but would I ride it even in normal times? Doubtful.
With DIYxGPS it makes it easier for some veloviewer tile bagging rides. Not quite within 10 miles but some of my rides don't have me going a huge distance away (especially if I get a train to/from a different starting point). Not sure I'd do a 200km VV tilebagging ride though, the constant direction changes and lack of real progress would sap away the motivation quite quickly.
There's something I dimly remember related to fractal geometry about the average "straight line routes" comparing on road distance (shortest route obviously) to as-the-crow-flies distance. Different countries (and different areas of individual countries) have different ratios. The worst case for a US grid style street system is sqrt(2) and best case is 1 but the average (for randomly chosen routes) is something like 1.2.
I think rural UK is also something like 1.2 as an average for random chosen routes too. Cities are often closer to 1 (assuming you don't have things like rivers without many crossings to contend with.)
Nicely planned tile bagging rides often pick off 2 tiles at a time going N/S or E/W without much deviation, and edge tiles don't cost a huge amount extra as you only need to sneak into the tile before backing out and going elsewhere, etc.
200km within 10km or so of me should be possible, probably even less, but that's because I'm in suburbia and there are a huge number of residential roads near me. If I knew how to obtain, parse and process the OSM data I'd have a go at writing something to find a really short route that avoids using the same stretch of road twice in the same direction. It just essentially boils down to a form of the Traveling Salesman Problem over a directed graph.
I did think about trying to write something similar to come up with semi-optimal VV tile bagging routes, but then I like creating those routes myself (often more than I actually like riding them). And there's no VV tilebagging right now given the current lockdown restrictions as my nearest unclaimed tile is definitely not "local" to me.
