Making Sport of Physics

Greipel gets us under 1%!

André Greipel took the last stage of this year’s Tour de France.  His time and a comparison with our prediction are given below.

  • Stage 21:  2h 43′ 08″ (actual), 2h 41′ 38″ (prediction), 01′ 30″ fast (-0.92% error)

We’ll definitely take that error to finish off this year’s race!  Greipel’s average speed is given below.

  • Stage 21:  11.54 m/s (41.56 kph or 25.82 mph)

The big prize, of course, goes to Chris Froome who makes it three out of four.  Froome is now in the upper echelon of Tour de France cyclists.  I was wrong to pick against the defending champion!  Froome’s average speed is given below.

  • Chris Froome:  11.00 m/s (39.60 kph or 24.61 mph)

Not bad for 3528.5 km (2192.5 mi)!  Congratulations to Froome and all the cyclists for a great Tour de France.  I wish I could have seen more of the race, but my family will soon be moving across the pond.  And we’ve got packing to do!

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Izagirre gets penultimate stage!

Jon Izagirre of Spain won this year’s final mountain stage.  Spain can celebrate its first Tour de France stage win this year!  Izagirre’s winning time and a comparison with our prediction is given below.

  • Stage 20:  4h 06′ 45″ (actual), 4h 01′ 44″ (prediction), 05′ 01″ fast (-2.03% error)

I’ll definitely take a 2% error on today’s stage!  Izagirre’s average speed is below.

  • Stage 20:  9.895 m/s (35.62 kph or 22.14 mph)

Chris Froome will win this year’s Tour de France tomorrow in Paris.  He has just over a four-minute lead on second place.  Our prediction for the lovely ride into the French capital is given below.

  • Stage 21:  2h 41′ 38″ (prediction)

I hope it doesn’t rain like it did last year!

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Bardet makes France proud!

Romain Bardet gave France its first stage win of this year’s Tour de France.  Below is Bardet’s time and a comparison with our prediction.

  • Stage 19:  4h 14′ 08″ (actual), 4h 04′ 57″ (prediction), 09′ 11″ fast (-3.61% error)

I’ll take that error on such an arduous mountain stage.  Bardet’s average speed is given below.

  • Stage 19:  9.575 m/s (34.47 kph or 21.42 mph)

Froome still has the yellow jersey, and he widened his lead over second place.  Nairo Quintana could only cut ten seconds off of Froome’s lead over him.  Tomorrow is the last shot climbers will have to take down Froome, but his lead looks mighty impressive for the final mountain stage.  A category-2 climb, two category-1 climbs, and an HC climb will have cyclists excited about the big downhill finish.  Our prediction is given below.

  • Stage 20:  4h 01′ 44″ (prediction)

Will Froome hold the yellow jersey?  Hard to imagine losing it the way he’s cycled this year.

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Has Froome locked it up?!?

Chris Froome showed why he’s a multiple Tour de France champion today.  He dominated the mountain time trial and makes me wonder if the Tour de France is over.  His winning time and a comparison with our prediction appear below.

  • Stage 18:  30′ 43″ (actual), 29′ 27″ (prediction), 01′ 16″ fast (-4.12% error)

I was hoping the winner would come in under half an hour, but Froome was impressive nonetheless.  His average speed is below.

  • Stage 18:  9.224 m/s (33.21 kph or 20.63 mph)

Froome won the first mountain stage and he dominated the mountain time trial.  I picked Nairo Quintana in my TOUR magazine interview.  Froome has a 04′ 37″ on Qunitana, and a nearly four-minute lead on second place.  There are two more mountain stages to go.  Time is running out!  Our prediction for Stage 19 is below.

  • Stage 19:  4h 04′ 57″ (prediction)

Besides an HC-climb in the middle, a category-1 climb finishes the stage.  Another uphill finish!

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Zakarin dominates the Alps!

Russian Ilnur Zakarin won today’s arduous mountain stage with a time nearly a minute faster than anyone else.  This is Zakarin’s first Tour de France stage win.  Below is Zakarin’s winning time and a comparison with our prediction.

  • Stage 17:  4h 36′ 33″ (actual), 5h 00′ 10″ (prediction), 23′ 37″ slow (8.54% error)

What’s funny for me watching a stage is that I don’t root for our prediction unless at the end I think we are really close.  I wanted to see the elite tackle today’s mountains and come in under five hours.  And did they ever!  Check out Zakarin’s average speed below.

  • Stage 17:  11.12 m/s (40.03 kph or 24.87 mph)

That speed is 2 kph faster than what race organisers had as their upper limit on the time schedule.  Incredible to average 40 kph today!  We aren’t happy to be more than 8% off today, but we’ll have plenty to study when the race is over.  Several determined cyclists clearly outputted more power today than we had in our model.  We’ll have a clearer picture of elite cyclist power output after this Tour de France is over.

Tomorrow’s Stage 18 is a 17-km (11-mi) mountain individual time trial.  Cyclists will be back in France for the uphill time trial.  They’ll get a chance to sprint on the downhill finish, though.  Our prediction is given below.

  • Stage 18:  29′ 27″ (prediction)

I definitely want to see cyclists coming in under half an hour tomorrow.

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Stage 17 Prediction

I’m busily getting items packed for our big move across the pond next week.  It hit me this afternoon that I’d not put our Stage 17 prediction online.  Well here it is:

  • Stage 17:  5h 00′ 10″ (prediction)

Cyclists will compete in the Swiss Alps tomorrow.  A great category-1 climb to the 1527-m (5010-ft) peak at Col de la Forclaz will tire cyclists.  But they’ll have to rejuvenate on the descent because the HC-climb to Finhaut-Emosson at elevation 1960 m (6430 ft) will challenge even the most elite cyclist.

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Sagan gets 3rd stage win!

Peter Sagan has really discarded the bridesmaid label in this year’s Tour de France!  I can recall so many stages in past years when he just missed out on winning a stage.  Below is Sagan’s winning time and a comparison with our prediction.

  • Stage 16:  4h 26′ 02″ (actual), 4h 46′ 38″ (prediction), 20′ 36″ slow (7.74% error)

We’re not happy with that error!  I don’t see any indication of tailwinds or anything similar that would make cycling fast today.  As I wondered at the end of yesterday’s post, sprinters must have been going all out today.  Check out Sagan’s average speed below.

  • Stage 16:  13.09 m/s (47.14 kph or 29.29 mph)

That is incredibly fast, especially for a 209-km (130-mi) long stage.  Even race organisers didn’t think the average speed would be above 44 kph.  To match Sagan’s time (and the time of several other cyclists), our model cyclist would have needed nearly 21% more power output.  We’ve done really well on a few stages this year, and we’ve had weather and teams’ strategies thwart us on a couple of other stages.  But we will have to take a closer look at today’s stage.  Tour de France cyclists certainly impress us!

Tomorrow is the second and final rest day.  Cyclists will hang out in Berne, Switzerland.  Chris Froome still dons the yellow jersey.  This year’s race will surely be decided in the Alps.  Get some rest tomorrow, cyclists.  You’re going to need it!

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Enjoyed a great time in Delft!

I’ll be using this space as a sabbatical journal for another fortnight or so.  Nothing comes to a close faster than a fruitful, yearlong sabbatical in England!  But I’ve made the most of my time here, professionally and personally.  I’ve written a good bit about various trips my family has taken, but I’ve not written as much about my research.  There is a good reason for that.  I was waiting to publish and present significant pieces of research.  More research is set to be published, but I’ll describe below some of the work that’s kept me busy this past year.  My time in the Netherlands last week will be the perfect vehicle for that description.

 
I attended the 11th Conference of the International Sports Engineering Association in Delft (click here for the conference webpage).  I had never been to the Netherlands before.  It was fantastic!  I am both thoroughly impressed and incredibly jealous of the biking culture there.  Wide bike lanes sit adjacent to car lanes.  It was so easy getting around.  The neighbourhood where I live in Virginia doesn’t even have sidewalks.  And biking is done at nontrivial risk because of speeding cars, a small fraction of which have drivers quite hostile to cyclists.  If my hometown had a biking setup like what I saw in Delft, I could easily see myself biking to work on a regular basis.  But riding on a 45-mph (72-kph) road, with some cars going well in excess of that speed limit, and no cycling lane make such an effort very unappealing.  Hopping back in my car when I return isn’t exactly something I’m looking forward to.  But cycling in beautiful Delft was a lot of fun.  The photo below shows me on my rented bike in front of the conference centre (click on the image for a larger view).

I relish going to a research conference.  Meeting up with colleagues I’ve not seen in a year or more is just as great as meeting a slew of new people.  Besides four great keynote addresses, I attended 37 talks and gave two talks.  I couldn’t see any more than that!  There were three parallel sessions, meaning lots of talks that interested me had to be missed.  As great as the talks were, the hallway discussions were even better.  Enthusiasm was contagious and it was easy getting excited about the smallest detail in another’s work.  The organisers at Delft did a terrific job.  We enjoyed great food for lunches and snacks, and the final conference dinner was a blast.  I also loved getting to know people over beer and Dutch food in one of couple of lovely squares in town.  All of us had the common feeling of love for our work and passion to learn more.  I definitely left the conference with new ideas and novel ways to think about current research problems in my head.
 
My research efforts contributed three papers to the conference.  I like that conference papers weren’t simply dumped without review into a “conference proceedings” book.  Papers for the Delft conference, like many other serious research conferences, were peer reviewed and allowed revision.  One of my papers benefited from a reviewer’s insight.  Another reviewer gave good advice for the oral presentation I gave.  Peer review is an indispensable step in the advancement of good science.
 
Chad Hobson, my talented undergraduate physics student from Lynchburg College, joined me in Delft for the conference.  It is important to me that my research students publish and present their work.  Not all my students are able to achieve a publication, but that’s a goal I’ve had since I began at Lynchburg College in 2002.  Chad presented our latest Tour de France work.  He is lead author on our paper (click here for that paper) and deservedly so.  His contributions to the work have advanced our Tour de France modelling in significant and critical ways.  Chad is in the middle of his talk in the photo below (click on the image for a larger view).

I’ve collaborated with colleagues at the University of Tsukuba on studies involving the aerodynamics of non-spinning soccer balls.  Previous work we published together showed why Brazuca was a better World Cup soccer ball than Jabulani.  I presented our current work that combined wind-tunnel experiments with trajectory analysis.  The latter approach is my speciality.  The photo below shows me in the midst of my soccer talk (click on the image for a larger view).

And, no, I’m not doing a Jedi mind trick!  The slide shows wind-tunnel force measurements, plotted in such a way as to illustrate stability, or lack thereof, in the five balls tested.  Click here for our paper.  We are getting a better understanding of knuckling effects.
 
My second presentation concerned part of the research I’ve done with my University of Sheffield colleagues.  We have investigated friction between various types of tennis shoe tread and a hard-court playing surface.  Sliding on hard courts isn’t as prevalent as it is on clay courts, but it’s becoming more popular.  I showed some of our treads in the slide below (click on the image for a larger view).

There are so many options for studying tread shapes and courts interacting with each other.  This research can certainly go on for years!  Our first paper on this topic is here.  We hope to have another one out soon.
 
Conference revelry was damped by the late-night news on Bastille Day that scores of people were killed in Nice.  And that news is on top of the seemingly continuous streams of bad news from my home country.  As I talked to people in Delft last week, I got such a strong sense of their hope and anticipation for future work.  I’m sure I exuded those desires as well.  Now think of all those killed in Nice and elsewhere.  Innocent people with hope and anticipation for their futures.  Gone.  Families ruined forever.  And for what purpose?  Making sense of the senseless is nearly impossible.  Maybe there will come a day when humans stop killing each other, but that day is a long, long way off.
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Pantano gets 1st Tour de France stage win!

Columbia’s Jarlinson Pantano won today’s stage, his first Tour de France stage win.  Below is Pantano’s time and a comparison with our prediction.

  • Stage 15:  4h 24′ 49″ (actual), 4h 22′ 06″ (prediction), 02′ 43″ fast (-1.03% error)

Wind was not the factor today that it was yesterday, and our model got us near 1%.   We’ll take it!  Below is Pantano’s average speed.

  • Stage 15:   10.07 m/s (36.25 kph or 22.53 mph)

Tomorrow’s stage finishes in Switzerland.  Our prediction is given below.

  • Stage 16:  4h 46′ 38″ (prediction)

The day after tomorrow’s stage is a rest day.  Will cyclists increase their rest by holding back tomorrow in preparation for the Alps?  Or will they go for it, thinking the rest day will be all that’s required before the big mountain stages?  We shall see!

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Cavendish gets 4th stage win!

Mark Cavendish won his fourth stage of this year’s Tour de France.  He won a stage in which riders fought massive headwinds all day.  One report I saw had the head wind nearing 40 kph (25 mph).  The wind killed our prediction, as seen below.

  •  Stage 14:  5h 43′ 49″ (actual), 4h 53′ 25″ (prediction), 50′ 24″ fast (-14.66% error)

I know why we were so off, but I still hate to see so large an error.  We had that same error on Stage 3.  That stage reinforced the idea that we can be off if team strategies’ are such as to hold cyclists back.  Today’s stage is a reminder that not knowing the weather can lead to a bad prediction.  Check out Cavendish’s average speed below.

  • Stage 14:  10.11 m/s (36.39 kph or 22.61 mph)

That is incredibly slow for a flat stage, even a long one.  The slowest average speed the Tour de France time schedule makers considered was 40 kph (25 mph).  To match the time for today’s stage, we would have needed to include a 10.7 kph (6.67 mph) headwind on our model cyclist — for the entire 208.5 km (129.6 mi).  We didn’t miss today’s stage because of poorly implemented physics.  We missed it because we had no idea ahead of time that riders would face headwinds.  But that’s part of the unknown associated with the modelling the Tour de France.

Tomorrow’s Stage 15 contains two category-1 climbs and a big HC climb.  The stage features a fast descent to the finish.  Below is our prediction.

  • Stage 15:  4h 22′ 06″ (prediction)

I like our prediction — as long as Mother Nature doesn’t get in the way!

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