Having finally seen it my two pennorth worth
1) Andy schleck needs to learn how to change gear properly
2) It was not a mechanical, it was what they would call in F1 "driver error"
3) It took andy a full ten seconds to even slow down and look at his chain
4) it took him more than 30 seconds to put the chain on after fannying around trying to put it on slack with it on the small chainring
I could have recognised the problem, stopped and fixed it quicker than the 40 seconds it took him. And it was kind of a basic error to start with.
Should contador have stopped, I dont think he had to and I have no problem with him not stopping, it wasnt a puncture, a failed part etc, it was rider error.
However, had he stopped he probably would have got serious karma for it. Similar to a few years ago in a football (soccer) match when the goalkeeper was down and the corner came in, paulo di canio caught the ball and gave it to the ref. He was within his rights to score, but decided to be sporting. AC could have been sporting. That said, if he had, i still think he would have attacked andy further up the hill and kicked his ****.
Andy made a mistake, AC was within his rights to carry on. But seriously, baby schleck needs to learn how to put a chain on. Interestingly both Roche and Hayles or whoever was in the eurosport studio said Andy was crap at putting a chain back on.
one thing i will say, is why is it, on a climb if a leader punctures, has a mechanical its considered polite to wait, but on the cobbles its anything goes.