Analysis: What is the fastest descending position?

Editor’s note: In February of 2021, the UCI announced pending bans of the super tuck and forearms time-trial road positions. In 2018, we tested eight aero road positions and ran our findings in the July 2018 issue of VeloNews. For complete and regular access to more in-depth stories like this, become a VeloNews Pass or Active Pass member today.

What goes up must come down. The Tour de France has almost as much descending as climbing, and time can be gained without exertion going downhill, particularly by heavier riders. Larger time gains usually come on ascents, but huge time losses and Tour-ending (even life-ending) injuries can be sustained because of poor descending. There are countless examples when descending speed made the difference to winning a stage.

We tested eight different descending techniques used in the 2018 Tour to see which was fastest. We named them after riders who have used them successfully. Six of these had been tested — with the results published — by Professor Bert Blocken of Eindhoven University of Technology, in the Netherlands.

How we tested tucks

We used a laser timer to determine the gap between two riders on roll-down tests of all of these descending positions. We chose the wide, relatively low-traffic hill up to the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, for our test run.

Two riders started each run adjacent a roadside reflector post, one approximately 80 feet behind the other. The riders started simultaneously, each taking a single half pedal stroke to start and coasting from that point on. The rear rider maintained a constant body position throughout all of the runs, with the large starting gap ensuring that he would not benefit from a draft from the front rider. The only (controlled) variable was the coasting position of the front rider.

Each rider had a piece of reflective tape running down the length of his right fork leg. I stood with my right foot on the road’s white line at a point approximately one kilometer (0.6 mile) further down the hill; I had a Star Crono Test laser timer strapped to my right calf that was tripped by the reflector on each rider’s fork as they passed within four feet of my leg (attaching it to a fixed post would have required the riders to come dangerously close to the road edge at high speed). The Star Crono Test records times to the thousandth of a second and saves 50 numbered files of time gaps for later review. I also timed it with an iPhone as a backup.

A larger time gap at the finish meant a faster position, as the front rider was rolling away faster from the rear rider. Conversely, a smaller time gap indicated a slower descending position for the front rider, since the rear rider was able to lose less time or perhaps even gain time on him.

Which aero tuck is fastest?

After the first run of eight different positions, three of them were so slow (indicated by small time gaps between the riders) that there was no point in testing them any further. These were positions #5 (Pantani), #7 (Froome), and #8 (Cancellara). After the next run of five positions, we also eliminated position #6 (Nibali, v.2) for the same reason.

At this point, we altered the protocol slightly to improve accuracy. We noticed that having the front rider immediately assume the chosen descending tuck position could lead to some wobbling at low speed in some positions, particularly the narrow ones or the ones hung over the stem. So, he instead held the Sagan position, the most stable at slow speed, for the initial 0.1 mile; then he switched to the chosen position for the remaining 0.5 mile. Since we were interested in how these positions compared at high speed, not low speed, we felt that bringing them all up to the same speed first before going into the position would make the test more accurate.

After one test with this new protocol of the remaining four positions, we eliminated position #2 (Mohorič). This position had consistently tested second fastest to the Phinney position (0.085, 0.088, and 0.097 seconds slower) and well ahead of the third and fourth fastest positions. It also posed the highest danger to the rider, as it offered the least control of the bike, hence its elimination for the safety of the test rider. It took some skin, too; on the 3T Strada aero disc test bike, the rider thought that by pinching the tall-section top tube between his knees, there was “no chance” of his knee hitting the front tire. That was until he hit his knee on the tire coming out of the Mohorič tuck on its final run.

We now wanted to find which position would take the third podium step, since the first two were clearly well ahead. We then performed three more runs of the Sagan position and two more each of the Phinney and Nibali tucks.

Taking a straight average of the total runs on each position gave us the ranking on the left of the table, with two positions tied for fifth. As there had been an occasional surprising outlier in some of the runs, we then threw out the one run (from each of those that had multiple runs) that most deviated from the others and averaged the times again. This did not change the order of the positions from fastest to slowest, but it did break the tie between the Pantani position and the Nibali position on the drops.

The positions (in order, from fastest to slowest):

1. Taylor Phinney

Sitting on back of top tube; hands tucked by stem.

Tucked low on the top tube, with his hands placed close together on the tops of the handlebars near the stem, Phinney dropped the entire field on the descent of San Marcos Pass on stage 5 of the 2014 Amgen Tour of California and held on to win the stage in Santa Barbara.

2. Matej Mohorič

Sitting on front of top tube; hands tucked by stem.

At the ripe age of 18, a year after winning the junior world championship, Slovenian Mohoric won the U23 world road championship in 2013 by holding off South African Louis Meintjes using this technique, alternately pedaling and coasting while sitting forward on the top tube, chest slung over the stem, head hanging down, and his shoulders as far forward as the brake hoods.

3. Vincenzo Nibali

Sitting on nose of saddle; hands tucked by stem.

On May 22, 2010, Nibali gave notice of his descending prowess and confidence on wet roads when he won stage 14 of the Giro d’Italia in Asolo. He dropped an elite group on the descent of Monte Grappa, switching back and forth between this position and position #6.

4. Peter Sagan

Sitting on back of top tube; hands on drops.

Sagan used this technique on stage 16 of the 2015 Tour to drop Jarlinson Pantano and almost catch breakaway rider Ruben Plaza. Sagan kept his back flat, head up, shoulders on the tops of his bars, and crotch firmly planted on the top tube with his butt slid back to the seatpost. Sagan held this position through turns of the technical descent of the Col de Manse.

5. Marco Pantani

Butt behind saddle; saddle against chest.

Pantani scooted off the back and rested his chest on the saddle while unsuccessfully chasing Richard Virenque down the Col du Tourmalet in the 1994 Tour de France. Cancellara has also been known to descend in this position.

6. Vincenzo Nibali, v.2

Sitting on nose of saddle; hands on drops.

Nibali has used this position many times to take corners at speeds that few riders can or dare to. However, the Shark of Messina also has his limits; he was leading the 2016 Olympic road race on the final descent before the run-in to Rio de Janeiro, when he crashed and took down Colombian Sergio Henao, at the expense of his collarbone and their almost certain podium positions.

7. Chris Froome

Sitting on front of top tube; hands on drops. Froome dropped a lead group of race favorites on the descent of the Col de Val Louron-Azet during stage 8 of the 2016 Tour de France. With his chest hung over his stem and his shoulders out to his brake hoods, he even pedaled frequently while sitting forward on his top tube, taking both the stage victory and the yellow jersey in Bagnères-de-Luchon.

8. Fabian Cancellara

Hands in the drops; up-angled back. In the 2008 Milan-Sanremo, Cancellara kept his hands on the drops and his head up as he wove through riders on the technical descent of the Poggio, enabling him to get to the front so he could break free on the flat run-in and win the monument.

But why are some faster and others slower?

We expected the two positions in which the rider sat on the saddle with his hands on the drops to be slow; top descenders only use these positions when they need greater control in corners or to avoid other riders, cars, or road hazards.

The Froome position, as Professor Blocken also found, tested slow. Hanging over the stem as Froome did bends the back, whereas the Sagan position, which Froome notably used last month in his crushing stage victory at the Giro d’Italia, gives the rider a more aerodynamic flat back and allows the head to be lower while still looking forward.

Pushing off the back of the saddle as Pantani did is also relatively slow because it spreads out the drag over a longer object, and it is wide — the hands and arms are further apart and scoop air into the pocket created by the body. It only achieves one objective of an aerodynamic position, namely getting the back lower.

The Sagan position—sitting on the top tube, shoulders on the bar tops, and hands in the drops—achieves the best combination of control and aerodynamics. It’s easy to steer and brake from this position while keeping the body flat and low.

The three tuck positions with the hands near the stem are the fastest because they are the narrowest; this is the same reason aero bars are faster than drop bars in a time trial. Nibali’s tuck on the saddle is a bit slower than the Mohorič and Phinney tucks, because the rider’s shoulders and butt are higher than in those other positions.

The Mohorič tuck offers little control of the bike, because so much of the rider’s weight is over the front wheel, and because the hands are trapped beneath the chest, making steering difficult. It was less than a tenth of a second slower than the Phinney tuck on all three of its runs.

The Phinney tuck, which is like the Sagan position but with the hands and elbows tucked in as narrow as possible, is visually a fast position. The back is flat and low, the head is low, yet the eyes can see forward, and it is narrow. It offers better visibility and control than the Mohorič tuck and is a hair faster.

The take-home points

The good news to come from this test is that positions offering the least control don’t offer a speed advantage. If you have a wide-open descent giving you the confidence to ride the Phinney tuck, that will be the fastest. The Mohorič tuck is not faster and thus doesn’t justify its inherent crash risks. The Nibali tuck puts undue strain on the neck to look forward with the back sloping down from a higher level.

When you need more control, moving the hands to the drops (the Sagan position) has no peer among positions offering braking and more steering control. And when you need more control yet, sitting on the saddle in the Nibali v.2 position should be the go-to.

There is a ninth position we considered testing, but for safety reasons, we decided not to test. Fixie rider Michael Guerra’s descending style is well documented on YouTube. He holds his body in a horizontal superman position, fronts of his thighs on the saddle, feet straight out the back, pedals spinning around madly, and no brakes. We have yet to see anyone use this descending technique in the Tour de France. Chris Case collaborated on the test and co-wrote this piece.

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