Crosswinds spliting the peloton

[Beeankey]

Can someone explain to me in simplish terms why what happened in yesterdays stage of TdF (stage 13) happens in crosswinds.

The same thing happened a few years ago when HTC split the peloton in a crosswind and Armstrong latched on leaving Contador for dead when they were both with Astana.

What is the reason a chasing group like Froome yesterday and Contodor that year find it so difficult to get back up to the breakaway.

I've never ridden in a big group so have no experience of this in practical terms and google is not offering much in way of explanation.

 

[Globalti]

Simples.... you'll have seen how each team leading each group was spread across the road obliquely in an echelon, actually vectoring into the side wind combined with the headwind of their movement so as to give shelter to the riders behind. A team of six can use the width of the road but anybody following them is forced to ride at the downwind edge of the road, partially exposed to the side wind on his shoulder. This is enough to ensure that a rider following a group finds it hard to hang onto their wheels and is likely to drop back, splitting the group into smaller bunches.

It's a little bit like when aircraft land in cross winds; they crab across the runway vectoring into the combined side and headwind.

Many riders were caught out by the split and by the time they realised they were off the back. Cav spotted it and was able to use his short-term speed to cross the gap, hence his position for winning the final sprint.

 

[Beeankey]

Cheers for that