By Miller MacDonald
Le Tour––the race of the year, a French cultural monument, a celebration of cycling’s simultaneous beauty and punishing ferocity—is widely regarded as one of the most difficult events in sports. Held over a three-week long period, riders push themselves to the limit on 21 stages that frequently last over five or six hours. Whether they’re elbowing each other at 40+ mph down a sprint straightaway, toiling up inhumanly steep roads in the French Alps, or racing alone against the clock during solo time trials, the Tour takes an extreme toll on riders’ bodies.
However, while the Tour de France’s level of difficulty has been and will always be reserved for superhuman athletes, that doesn’t mean that each Tour is created equal. In fact, several factors point to the possibility that the Tour has been getting easier over time. But what does “easier” mean, exactly? And does an easier route mean an easier race? Here we examine several factors that contribute to and indicate the difficulty of the Tour de France: distance, dropouts, and speed.
WHAT IS THE TOUR DE FRANCE?
The Tour de France is one of cycling’s Grand Tours, which are multi-day races split into day-long stages. While the length and number of stages has varied considerably in the past, currently there are 21 stages in the Tour along with two rest days, resulting in a 23-day race. Stages come in three main categories: sprint stages, where the peloton races along largely flat roads, mountain stages, where riders fight in the high mountains (usually the Alps or the Pyrenees), and time trials, where riders race solo against the clock to achieve the fastest time crossing the line. The rider with the lowest cumulative time at the start of each stage wears the yellow jersey, and the rider with the lowest cumulative time at the end of the Tour takes the jersey home as the winner of the general classification.
DISTANCE:
When determining the difficulty of a race, one of the first and most obvious things to consider is the distance over which the riders have to race. As a rule of thumb, as distance increases, so does fatigue, attrition, and overall difficulty. Looking over the Tour’s history, there has been a clear shift towards designing shorter and shorter courses over time. There has been a steady progression in shortening the total length of the race (R^2 = 0.449): the 10 longest Tours took place in the first 30 years of the event, while (discounting the first three Tours, which had a wildly different format to the rest of the races) 7 of the shortest 10 Tours in history have occurred since 2002 (all 10 were raced in the past 35 years). While the 1926 Tour, the longest in history, covered a whopping 5745 km in 17 stages, the 2002 Tour only covered 3274 km over an expanded 21 stages, the shortest distance aside from the three initial Tours.
In addition to a decrease in total distance over time, the lengths of individual stages have also dwindled. The longest stage in each Tour has gotten progressively shorter over time (R^2 = 0.754); from 1919 to 1924, each Tour featured a stage that was 482 km long, over twice as long as almost every stage in the 21st century. The longest stage in the upcoming Tour de France only covers 209 km, the shortest among longest stages in history.
Notably, there is little to no statistically significant decrease in shortest (road) stage length over time (R^2 = 0.299) (as opposed to time trial stages, which can be as short as a few kilometers). However, it is difficult to account for this specifically, given that in many cases the shortest stage is such due to last-minute stage shortenings caused by inclement weather (for example, stage 19 of the 2019 Tour de France was shortened mid-stage to 89 km due to landslides on the descent from Col d’Iseran, making it impossible for riders to continue the race).
DROPOUTS/OTLs
Another diagnostic factor that seems obvious to look at when determining the difficulty of a given edition of the Tour de France is the number of riders that drop out of the race each year. It seems likely that a higher attrition rate––the number of riders who drop out divided by the number who start the race––implies a greater difficulty. Over time, the attrition rate has noticeably dropped (R^2 = 0.694), with several editions during the first two decades of the Tour having over 80% of starting riders drop out. Conversely, in the past 20 years only one Tour has had over a 25% attrition rate.
There are several problems with using attrition rate as a diagnostic factor for difficulty. Notably, riders can abandon the race for a multitude of reasons completely unrelated to difficulty-related symptoms––for example, the past two Tours have had the highest attrition rates since 2007 largely due to COVID-related abandonments. Additionally, many riders drop out due to injuries incurred through crashes, which are many times more related to slippery roads or errant spectators/road furniture than fatigue.
We can further validate these qualifications by considering another specific reason why riders drop out––the OTL. Each stage of the Tour is, through an opaque combination of factors, assigned a time limit, where riders who finish outside the time limit, or OTL, are eliminated from the race. When looking at race difficulty, it is arguable that in a vacuum this statistic is more closely related than overall attrition rate––if more riders finish outside the time limit over the course of a Tour, it stands to reason that the race was more difficult that year. However, when isolating OTL dropouts and plotting against distance (over the time period where OTLs have been present in the Tour), we surprisingly see a weaker correlation (R^2 = 0.125) than we do for general dropouts vs. distance (R^2 = 0.548). This could point to a looser connection between OTLs and difficulty as a result of factors like inconsistent time limit determination methods.
SPEED
While this analysis so far has only considered the difficulty of the course itself, another glaring factor in race difficulty is the way the riders choose to race the course. A seemingly back-breaking route over hundreds of kilometers through the high mountains may, in certain situations, be ridden at a relatively pedestrian pace and result in less fatigue than a flat or hilly stage that is taken at backbreaking speeds.
While it is fairly indisputable that the courses, or parcours, of the Tour de France have gotten easier over time, the speeds at which the riders race over these parcours have considerably increased over time (R^2 = 0.893), adding nuance to the difficulty conversation. In fact, the average speed of last year’s Tour de France was the fastest in history, with the winner Jonas Vingegaard finishing the route at an average pace of 42.102 km/h. This is almost certainly in part due to the shortening of the course over time––however, increased quality of competition and new aggressive racing strategies could also play a role.
However, even more so than most sports, technological advances could prove to be another lurking variable behind this trend. With bike frames, helmets, and jerseys getting dramatically lighter and more aerodynamic, even in the past decade, the exact same parcours with the exact same riders could be ridden significantly faster today than thirty years ago.
Because increased aerodynamics of equipment present more of an aid at faster speeds, we can look at stages with greater amounts of elevation gain to better parse whether the increasing speed of the Tour is due to tactics or technology. While elevation gain data is only present for races since 2002, in this 20-year time frame there is almost no increase in average speed of the stage winner over time for stages with over 3000 meters of elevation (R^2 = 0.012) or 4000 meters of elevation (R^2 = 0.0012). Considering these data, it seems that speed trends over the course of the entire Tour do not carry over to the high mountains.
Another factor to consider here is the proven presence of the performance-enhancing drug EPO in the Tour in the early and mid 2000s. As such, under the assumption that current riders are clean, the little change present in climbing speeds could in fact signal a greater intensity at which these stages are ridden.
THIS YEARS TOUR DE FRANCE
When looking at the 2023 Tour de France, it is hard to predict where it will fall in terms of difficulty. In terms of the pure parcours, it is the 13th shortest in history, with the shortest longest stage in the race’s history. However, it is also likely that the course will be ridden just as ferociously as last year’s race, with successful breakaways few and far between and with epic battles in the high mountains. It is impossible to predict the attrition rate, especially without knowing the exact weather conditions present on the days the stages will be raced.
Last year’s winner, Jonas Vingegaard, will be returning with an incredibly strong team in Jumbo-Visma, who dominated last year’s Tour de France, winning not only the yellow jersey but the sprinter’s and climber’s classifications as well. Tadej Pogačar also returns as the top-ranked cyclist in the world by the UCI, having won the 2020 and 2021 Tours and coming 2nd to Vingegaard last year. However, he is fresh off a crash from earlier in the spring and has not appeared in a major race since then, so his fitness remains questionable. Expect fiery battles from the favorites on fabled climbs like Puy de Dôme (stage 9), le Grand Colombier (stage 13), and Col de la Loze (stage 17), but no guarantees.
One thing is for sure, however––whether this year’s Tour de France is the easiest on record or not, by tuning in you will still be watching athletes compete in one of the most taxing, attritional, and glorious sporting events in the world.
