In reply to GrahamD:
There's no doubt that there is a widening gulf in attitudes between cyclists and drivers.
Compromise requires movement from both sides. I don't see any offer of movement from the anti cycling lobby other than -
Use cyclepaths (regardless of their suitability - but watch-out these have carefully laid trip wires)
Pay road tax (that no one pays)
Get insurance (that most serious cyclists have anyway - it's cheap because bikes do very little damage)
Wear hi-vis (a lot do)
Wear a helmet (Most do)
don't ride 2 abreast (as the law allows)
Don't "take the lane" (as the government and every other cycling body suggest)
Don't ride in groups (even though they are easier and safer to overtake)
Stop holding up traffic (the clue is that we are all traffic)
None of this sounds like compromise to me.
For what it's worth, I do think you are on to something with regards to avoiding causing undue inconvenience, but the way to resolve it isn't for the vulnerable user group to bend over and take it.
Sportive type events are one of those things that are a bit of an oddity and can cause particular issues on specific roads on a particular day. I think its fair to say that they could do more to warn in advance that a lot of cyclist will be on those roads to give people a chance to avoid etc. I also think Sportives should be regulated to a much greater extent as there are some areas (Surrey Hills for example) that seem to have a sportive going through every other weekend in the summer - spread them out more, maybe restrict numbers more, and encourage more, larger capacity closed road events. People of course complain about closed road events too, but they are few and far between, and are probably outnumbered by Marathons/Charity Runs (I can only think of 4 including the new Cambridge one - Caledonia, Wales, Ride London, Cambridge Gran Fondo)