Nacho said:
What bothered me most about this leg of the TdF was this: Fonseca made the break-away and then the peloton settled in to a day of soft-pedaling. But why should the peloton soft-pedaling affect what Fonseca did? If you watched the times they showed Fonseca at the front, you would see he was soft-pedaling too! That is not the way break-aways go! They mostly pedal to their max all the way until the end or they are caught by the peloton.
Firstly, no need to apologise for being new. Everyone was new once. And it's a good question.
Think of it as cat and mouse. The peloton don't think "I want to catch him as early as possible", they think "I want to catch him before the end". Also the peloton isn't one guy or even one team, it's many teams against each other all trying to do the least work. So if he slows up the peloton think "what's the panic, he's cooked" and the guys at the front, who know they have to work for their sprinter later on, go "ok, let's not go too nuts and waste ourselves, we'll catch him very soon anyway". Everyone has radios, so they know the effect of their efforts straight away.
Tony Martin's famous Vuelta stage a couple of years ago had a lot of this - he played dead several times to buy himself more time.