congestion was an issue, caused a few problems too.
There was a bit of a tangle on the bottom of the first descent – no injuries, but I heard something about a bent £500 derailleur?!
Lots of the climbs there are only two or three lines up, so mixing slow/fast, patient/impatient people led to a few abrupt stops.
After the first water stop it really thinned out a bit, and by lunch it was fine.