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June 20, 2021

How Hard are the Tour de France Stages for Cyclists?

We break down the difficulty of various Tour de France stages as riders take on the mountains, flat sections and time trials, using WHOOP data and other metrics.

By Jeremy Powers

The Tour de France is widely considered one of the most grueling and difficult athletic events on the planet. For 21 stages spanning 23 days, cyclists push their bodies to the max–day, after day, after day, after day. How hard are the various individual stages?

We wanted to take a look at data we’ve been able to capture over the years from the big stages of the Tour de France, as well as the Giro d’Italia, another Grand Tour stage race that is three weeks long. We can use this data to better understand the incredible effort that these riders will undertake at this year’s Tour de France.

 

The Strain and Exertion of Tour de France Stages

Generally speaking, a “normal” day at the Tour has a rider putting out somewhere around 230-250 watts on average (think of this as pressure on the pedals), which equates to about 900 kilojoules (a fancy way to say calories) per hour. Multiply that by 5 hours and it’s almost 5000 calories! And more often than not, this equates to a WHOOP strain score above 20 (strain is how we measure cardiovascular exertion, on a scale of 0-21).

On some of the harder stages, this is closer to 300+ watts and 1100 calories/KJ per hour. Even for the fittest athletes in the world, this is a wild number and gets your cardiovascular system really fatigued. Strains over 20.5 are not uncommon.

 

Daily WHOOP Strain Data from Each of Last Year’s Tour de France Stages

This graphic shows the average strain (in blue) for members of the EF Education – NIPPO Pro Cycling Team during each stage of the 2020 Tour de France:

daily tour de france strain

The average daily WHOOP strain and recovery for EF riders DURING THE 2020 TOUR DE FRANCE.

Below we’ll take a look at some of this year’s Tour de France stages (a mountain stage, a flat stage and a time trial) and break them down based on data we have from previous races.

 

Mountain Stage & High Strain

Stage 8 of this year’s Tour de France is the first true mountain stage:

Distance: 94 miles (151 kilometers)
Elevation: 11,000 feet of climbing
ETA to Finish Stage: 5 hours, depending on weather, heat, etc.

Tour de france stage 8

The layout of Stage 8 in the 2021 Tour de France.

If we look at the last time we visited this stage, we actually have data from Lawson Craddock in 2018. Back then, it was Stage 10 of the 2018 Tour de France. To give you a sense of things during that moment, at the time Lawson said this to us:

“It was a rough day for me. I felt better than expected on the first climb, but that feeling was short lived. I suffered over the second mountain pass, but once we hit Col de Romme I was cooked.”

Lawson had a solid 70% WHOOP recovery that day with a 20.6 strain, his most strenuous stage of the Tour to that point. His average heart rate for the ride was 146 beats per minute, his max heart rate was 183 bpm (near his top) and he burned around 4,600 calories/KJ.

To use another example, Stage 6 of this year’s Giro d’Italia was also a very similar alpine stage–100 miles, roughly 5 hours of riding and 11,200 feet of climbing. Here’s a glimpse at some of EF rider Simon Carr’s metrics from that stage:

Recovery: 25%
Day Strain: 20.5
Average HR: 145 bpm (nearly identical to Lawson’s mentioned above)

The Giro’s Stage 6 had comparable terrain, mileage and elevation to Stage 10 of the 2018 Tour de France, and to what we’ll see in Stage 8 of the Tour this year.

On these big climbing days there is no hiding. We can almost certainly expect the riders hitting strains of 20.6 and higher, and hopefully they’re waking up in the green ready to take on this massive day. But with it being the 8th straight day of competition, following a hectic first week and no rest days yet, chances are this is going to be a stage of attrition. Napping, blue light glasses, nutrition, hydration, massage, focussing on sleep consistency… literally every recovery method in the book is what the riders will be striving for leading into and after a huge stage like this.

 

Flat Stage & Max Heart Rate at the Finish

Stage 19 of this year’s Tour fits this billing:

Distance: 129 miles (207 kilometers)
Elevation: 4,120 feet of climbing
ETA to Finish Stage: 5 hours and should end in a sprint

2021 tour de france stage 19

THE LAYOUT OF STAGE 19 IN THE 2021 TOUR DE FRANCE.

Now that we’ve seen what a day in the mountains looks like, let’s crunch a little data from some flat stages. These stages of a Grand Tour tend to be “easier” relative to what the riders are doing on the hillier days. Here’s a snippet of what we wrote during the 2018 Tour:

“Lawson completed Stage 07 today, spending more than six hours on the bike. It was a long, mostly flat stage referred to as ‘boring’ by a few riders.”

This is less true on days when certain riders have to “ride in the front” for the team’s sprinter or “get in the breakaway,” so let’s exclude those and just focus on a typical flat stage from someone who’s “sitting in the bunch.”

At the Giro this year, the 13th stage was 126 miles long and flat as a pan. Simon Carr only burned 2700 calories/KJ with a WHOOP day strain of 15.9. This is an atypical stage of a Grand Tour, but it highlights just how different each day can be. Also, towards the end of these flatter stages it’s often very chaotic and dangerous as they come into the finish line, and it gets going fast.

Looking at Simon’s heart rate data from this stage, you can see that he is full gas in the last 30-45 minutes and maxed out his HR just to finish in the pack.

flat stage heart rate

Simon Carr’s heart rate during the flat Stage 13 of the 2021 Giro d’italia.

Time Trial Stage & Non-Stop Elevated HR

Stage 5 of the Tour this year is a time trial:

Distance: 17 miles (27 kilometers)
Elevation: 1089 feet of climbing
ETA to Finish Stage: 30 minutes

2021 tour de france stage 5

THE LAYOUT OF STAGE 5 IN THE 2021 TOUR DE FRANCE.

Time trials are dubbed “the race against the clock,” which is a short (usually under 60 minutes) but constantly hard individual effort. The strain we see is different from any other days of a Grand Tour. If the riders pace it right, their heart rates will be lower at the beginning and progressively go up and up to the finish line.

When you factor in what they do to warm up and cool down it can still end up being a “big day”–especially considering riders often need to finish within a certain time percentage of the winner in order to stay in the race. They can’t go out there and lallygag even for a moment, they have to keep moving even if they’re not in the hunt for the overall or stage win.

Lawson completed Stage 20 of the 2018 Tour (a 31-mile time trial) in just under 48 minutes, and his day strain still topped 16. Similarly, Simon hit a strain of 16.6 at the Giro’s Stage 21 time trial this year, despite being on the bike for only 18+ miles and 36 minutes. However, he spent 33 of those 36 minutes at 80% or more of his max heart rate, with his HR rarely dipping below 160 bpm the entire time.

 

The 2021 Tour de France begins June 26th, covering 2,123 miles across its 21 stages. Check back when the race is underway and we’ll have fresh data to share from EF Education First – NIPPO riders.

 

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Jeremy Powers

Jeremy Powers, known to many cycling fans as JPows, is a retired professional road, mountain and cyclocross rider. After calling time inside the course tape, he worked for the Global Cycling Network showcasing all kinds of interesting stories within cycling, racing news, and culture, as well as doing co-commentary on the cyclocross races each weekend. Jeremy now helps WHOOP in all things cycling related.

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