Not a Strava user - but the mention of 70mph winning speeds, makes me think that Strava should eliminate segments from their database where in order to win you need to violate the speed limit. As a baseline they should not be encouraging people to break the law.
It's not just the user of the program that should be taking personal responsibility, but the coders as well.
For the sake of argument, imagine they did calculate the (average??) speed limit for each downhill segment.
Then what?
They hide anyone who goes over that speed from the leaderboard, so the leaderboard is full of people who managed to average precisely the speed limit?
Or as soon as someone goes over the average they hide the whole leaderboard like they do for flagged segments now?
My proposal is that they should hide the leaderboard for all segments over (say) 3% average negative gradient. Simple physics predicts that -3% gradient will put you over the speed limit in most jurisdictions, and it's much simpler to work out.
I’d assume they’d do what you suggest they already do sometimes - make the segment without a leaderboard. Just show your times.
I like your suggestion better than mine. But it seems that Stava is trying to shirk as much responsibility as possible, and as such your suggestion seems less likely to get implemented.
My proposal doesn’t involve them doing anything good - it just has them no longer encouraging blatantly illegal behavior. It’s a minimum bar that should be code-able in minimum time. Almost all of the dangerous segments would still have leaderboards - only the blatantly illegal ones wouldn’t be and they could say that they "do not encourage illegal behavior" - something they can’t honestly say now.
It's not just the user of the program that should be taking personal responsibility, but the coders as well.