Rain and Crashes Mar Stage 5!

Today's Stage 5 was a mess.  The start of the race saw winds blowing from the northwest to the southeast at 30 kph (19 mph).  Because the stage took riders mostly due south, they had tailwind components for the majority of the stage.  Winds slowed a little as the stage wore on, but stayed at least 15 kph (9.3 mph) and in the 20 kph (12 mph) - 25 kph (16 mph) range over the last third of the stage.  When I saw the huge tailwinds, I knew our prediction would be too slow.

Winds helped riders, but they also had to contend with a lot of rain.  There was enough water on the roads that two of the nine cobblestone sections were deemed too dangerous and removed from the route.  The stage was 3 km (1.9 mi) shorter than it was supposed to be, and the entirety of the 3 km removed was cobblestone road.  Coupled with the tailwinds, losing 3 km of slow cobblestones meant that our prediction would be really slow.

The image below is one I cropped from my video feed.  It shows the first section of cobblestones (click on the image for a larger view).

Note how dangerous the edges of the road are.  I saw many crashes, and some riders almost got stuck in the muck.  The image below is one I cropped from the second cobblestone section.  It shows the seven lead riders at that time (click on the image for a larger view).

The most notable crash today was that of Christopher Froome, who won the Tour de France last year.  His second crash of the day cost him the rest of the Tour de France as he had to limp into a car and retire from the race.  That leaves Team Sky without a leader because Bradley Wiggins was left off the team.

Despite the terrible racing conditions, the lead riders were averaging about 48 kph (30 mph) after two hours in the saddle.  I knew the tailwinds helped a great deal, but I was still impressed riders could bike that fast in the rain.  The seven cobblestone sections slowed them down in the latter part of the race.

Lars Boom of Netherlands was spectacular today.  He navigated all the cobblestone sections flawlessly and was a tour de force at the stage's end.  He was pumping his pedals like crazy to make sure he would get the stage win.  The image below shows Boom crossing the finish line (click on the image for a larger view).

Note his muddy face.  Riders finished up today with mud all over their faces, clothing, and bikes.  Below is a comparison between Boom's time and our prediction.

• Stage 5:  3h 18' 35" (actual), 3h 34' 03" (prediction), 15' 28" slow (7.79% error)

The tailwinds and 3 km less cobblestones killed our prediction, so I'm not terribly perturbed by the error given that we modeled a longer stage without wind!  At our average speed prediction, taking 3 km off removes just over 4' off our prediction.  Tacking on a continuous horizontal tailwind of 4 kph (2.5 mph) knocks another 12' off our prediction, which would have gotten us a lot closer to Boom's time.  If only we could know the weather ahead of time and know if a stage will be shortened!

Boom's average speed is given below.

• Stage 5:  12.80 m/s (46.08 kph or 28.63 mph)

The tailwinds helped, but that's an amazing average speed with seven cobblestone sections.

Tomorrow's flat Stage 6 begins in the northern French city of Arras and then moves 194 km (120.5 mi) southeast to Reims.  There are a couple of category-4 climbs, but the stage has a flat finish.  Below is our prediction.

• Stage 6:  4h 29' 39" (prediction)

We hope there aren't huge tailwinds and rain tomorrow!