In reply to andy guppy:
Jeez the perils of being honest !!!!
I'm at work and don't have Eurosport anyway, so I follow the race via twitter and whatever footage gets posted online. So I had seen the footage posted above, and in fact the last 15 minutes of the race.
The footage however doesn't show the crash itself and more importantly the state of affairs at the head of the peloton as it passed the roundabout. So I made an assumption, and stated it as such, that the race was going full speed at this point. After all they were only 11k from the finish and approaching the climb. Now, having read and heard a few reports, it seems my assumption was correct. If have links to footage or reports which show otherwise I'd be very interested to see them.
So what is the etiquette ?. First of all time for more honesty. I am not, nor have I ever been, a professional cyclist. Or even an amateur racer. In fact my only race was on a mountain bike!
My understanding is that it is bad form to attack when a rival has a mechanical, puncture or crash. It happens of course. However if an attack has already been made and you suffer a problem then tough , that's racing. It's also common sense - spectators don't want to see riders riding piano every time there's a crash, particularly so close to the finish. Even if Evans had gone at my pace on the final climb Purito wouldn't have caught him.
Remember "Scleckgate" - Schleck attacked, Bertie countered and Schleck's chain slipped. Blame the mechanic, blame the kit but you can't blame Bertie for not checking Schleck's chain as he went past.
Yes Ullrich waited for LA when a kid took him out (the world owes that kid an apology), but that was quite early in the stage, and of course LA attacked on the last climb and won. And when Beloki crashed and LA went through a field, no one was going to wait (not that it made any difference to Beloki).
If neutralising the race is necessary for safety, or to get ambulance through, then the commissars should do it, but it's not a decision that can be made by a rider on a final push for the line.