Hmm. Been watching this thread develop. I think it's a fine line between taking the lane (which as "vehicles" we are undoubtedly permitted to do) and causing an obstruction.
However much we might decry motorists squeezing past in unsuitable circumstances, and would like to stop them doing so, I don't believe we have any right to deliberately obstruct them to prevent that happening. It is not our role to enforce the law or good practice.
But having said that there are often ways of justifying the line (keeping out of the door zone being a good one).
I'm afraid I couldn't disagree more. It is wholly the responsibility of the person carrying out the (often pointless) overtake to do so safely. It is not incumbent on vulnerable road users to facilitate the manoeuvre, particularly if so doing compromises their safety. 'Stuck' behind a cyclist? Just bloody well wait a few seconds. I drive a van all day and it hasn't caused me a coronary yet.
I'd agree with Phil in that there's no need to cause
unnecessary obstructions - if you've got adequate road skills you should be confident about letting heavy traffic past with narrow tolerances. Eg I've often seen cyclists take "the whole lane" when moving out in 2- or 3-lane roads, when they need to be on the white line and let traffic pass in the same lane.
I always try to move out on the approach to roundabouts, but drivers usually hate it. Recently I did this and 'forced' a car onto the wrong side of the road before it popped back in front of me. I was able to follow it to its home destination and waited, on my bent, for the driver to get out, which took rather a long time. It turned out to be a gorgeous teenage girl - I told her she was a bl00dy lousy driver and she was most apologetic, explaining she'd only just passed her test and lacked experience!