Will dropper posts break into the pro peloton?

By now, we've all seen the furore surrounding Matej Mohorič's tactical use of a dropper post at Milan-San Remo. The Slovenian master descender's Merida Scultura Team race bike was fitted with a Fox Transfer SL Performance Elite dropper post, and he used it to great effect on the fast descent off the Poggio, the final climb that regularly shapes the race. After going over the crest of the climb, Mohorič attacked, dropped his seatpost, and very quickly dropped his competitors too, getting enough of a gap to stay clear until the finish. 

He spoke freely about his technological marginal gain at the finish line, about how he'd been planning it since winter, how he'd showed it off to his competitors earlier in the race, before joking that he'd "destroyed cycling," because "now everyone will start to use dropper posts". 

But will they? Is there any truth in Mohorič's jesting? 

Once a race is won with a technological marginal gain, you can be sure that every other team goes into overdrive thinking about how they can get the same free speed. You can bet that as I was writing this piece at the start of this week, team staff were on the phone with sponsors to find out what was possible.

Cycling history is awash with such moments. When Mark Cavendish wore an aerodynamic shell over his helmet at the 2011 World Championships and won, Lotto Belisol copied it, and soon after the birth of aero helmets followed. Similarly, after Greg LeMond used aero time trial bars and an aero helmet to overhaul Fignon on the final day of the 1989 Tour de France, the time trial scene never ignored aerodynamics again. 

So are we in the midst of another of these history-making turning points in our sport?

Why dropper posts might catch on

Faster, safer descending

The benefits of a dropper post for descending are widely touted in mountain biking. The ability to drop your saddle out of the way allows a rider to hang their weight behind the bike, over the rear tyre, helping to maintain balance and control on super steep drops and descents. 

It also makes a bike more manoeuvrable: without a saddle hitting the inside of the legs, the rider can move the bike around beneath them more freely, theoretically providing more cornering stability at higher speeds. In addition, the reduced saddle height, and thus the reduced rider height, will also lower the centre of gravity. 

And finally, and perhaps significantly for road cyclists, the reduced rider height would theoretically reduce the rider's frontal area. Mohorič was a prolific user of the now-illegal supertuck position, which saw riders sit on the top tube on descents in order to significantly reduce frontal area, thus being less impacted by the onrushing wind and therefore going faster for the same effort. It was a wholly inefficient pedalling style and it made steering a difficult task, but the benefits of free speed were so great that as soon as the road pointed down it was a common sight in the WorldTour peloton until the UCI outlawed it on safety grounds in 2021. 

The dropper seatpost will theoretically achieve a fraction of the same reduced-frontal-area in a safer way, and the UCI has already come out to confirm its legality in light of Mohorič's victory.

Muscle fatigue

Mohorič isn't the pioneer of the road-bike-dropper-post movement (yes, we're calling it a movement now). Vincenzo Nibali, one of the most capable descenders of the past decade, has been trialling dropper posts for years. Various twist-to-adjust droppers have been spotted on his bikes, most commonly during his time at Astana. However, despite the touted benefits to descending control, the Italian's motivation has repeatedly been cited as an ability to finitely adjust his position for comfort as his muscles fatigue over the course of a three-week grand tour. 

Comfort

It is possible to integrate a little bit of road-smoothing to the dropper post's stroke. Suspension seatposts are nothing new, and last year, RockShox launched a dropper seatpost into the XPLR ecosystem of gravel components alongside Zipp and SRAM. To negate the fact that a round aluminium seatpost was stiffer than a carbon one, it was given a few millimetres of cushioning to absorb the vibrations from the terrain. In theory, this feature could be adjusted from solid to squishy depending on whether smooth Alpine tarmac or brutal Flandrien cobbles are on the menu for the day. 

Better bike swaps

The other case for dropper posts comes from a completely different line of thinking, and that is bike size. Anyone who remembers Esteban Chaves being forced to swap bikes with Damien Howson – who is 24cm taller – at the 2019 Vuelta will need no further explanation as to how a dropper post can benefit a rider in the event of a mechanical-induced bike swap. 

Richie Porte preempted such a situation at the 2017 Tour de France, when he was team leader at BMC Racing. His teammate Danilo Wyss rode with a second clamp fitted to the seatpost set at the correct saddle height for Porte, with a quick-release lever beneath. This effectively allowed Porte to drop the saddle in seconds to his perfect height. It was different to the sort of post used by Mohorič, but the latter would serve a similar purpose. 

Why dropper posts probably won't catch on

They won't fit

The most overwhelmingly obvious reason that dropper seatposts won't become widespread in the pro peloton is that they simply won't fit the majority of bikes that pros are using. Nearly all race bikes nowadays are specced with a proprietary D-shaped seatpost, because it has been proven to be more aerodynamic and better at absorbing vibrations from the road beneath. 

The reason that Mohorič was able to use one at all is that Merida chose to stick with a round seatpost – a decision that no doubt had nothing to do with dropper posts – when designing the latest Scultura. The only way that a dropper post could be fitted to most of the pro peloton's bikes would be for each bike brand to develop its own proprietary version for each bike. Trek, for example, would need to develop two, since its aero Madone and lightweight Émonda use different seatpost designs. 

The only way this could potentially be shortcutted would be for brands to create an adaptor that would allow a round post to be fitted into their non-round seat tubes, but that would require a new dropper post to be created that's even more narrow than any currently available. If brands thought that there was enough consumer appetite for such a thing, they'd probably have already made the investment, or they'd more likely have stuck with round seatposts in the first place. 

In the real world – not the final moments of the longest Monument of the season – dropping a seatpost out of the way isn't really going to benefit anyone enough to make it a worthwhile upgrade. 

Round tubes are slower

Thinking of those brands that have already adopted a D-shaped seatpost, they've spent many an hour in the wind tunnel testing the aerodynamic benefit of swapping from a round seatpost to one with a flat back, D-shaped, truncated kammtail shape. It's widely accepted that the shape is faster, and the fact that so many brands have made the switch is enough confirmation of the fact in itself. 

There will undoubtedly be parcours on which the seconds gained from swapping to a dropper post could outweigh the seconds lost from losing the more aerodynamic D-shaped seatpost, but those are going to be very uncommon, especially as aerodynamics plays an exponentially greater role as speed rises. 

Dropper seatposts are heavier

There's no doubt that a seatpost with two aluminium tubes and a host of internal gubbins is going to be heavier than a hollow single wall tube of carbon fibre, and pro cyclists don't like adding weight to their bikes. Ever since disc brakes found their way onto the pro peloton's road bikes, teams have had to work harder to bring their bikes' weight down to the UCI's minimum limit of 6.8kg – many of them failing – so there won't be a queue of riders desperate to add another 50-100 grams to their bike. 

Further to the previous point, what comes down must first go up, and any race with a descent steep or long enough to benefit from a dropper post will likely have a pretty unpleasant climb too. It's rare that too many riders will want to purposefully give away time on the climb in hope that they can gain it back afterwards.  

They can't actually be dropped that far

As explained at the top of this article, mountain bikers like dropper posts because you can drop the saddle right out of the way. However, in clarifying the legality of dropper posts in the WorldTour, the UCI reiterated the point that their use is still subject to the minimum 5cm setback rule of article 1.3.013 of the UCI Regulations. This rule states that the peak [front] of the saddle shall be a minimum of 5cm to the rear of a vertical plane passing through the bottom bracket spindle'. 

If a rider were to drop the saddle right down to the frame (to drop it completely out of the way) this would effectively bring the saddle forward at the same time, since seatposts are angled rearwards. This, in turn, would bring the nose of the saddle within 5cm of that bottom bracket vertical plane. Therefore, the rule limits how far the seatpost can be dropped, reducing the benefit that it provides to control and aerodynamics. 

In conclusion

To sum up, dropper seatposts have their advantages, but the areas in which they benefit professional riders are limited, and their adoption is hindered enormously by the lack of compatibility with most brands' frames. 

Mohorič found a very specific situation in which the dropper post could benefit him, and was fortunate enough that this bike would accept one, but it was far from the only factor in his victory. Getting over the Poggio in a good enough position to be able to launch an attack was obviously key, and there were complaints of motorbike assist from fourth-placed Michael Matthews, but perhaps most significantly, Mohorič is an incredible descender who took risks that nobody else was willing to take. 

The following quote from Tadej Pogačar says it all: “He went into the left hairpin and he was drifting and even went off the road a bit. It was a bit crazy so I told myself not to follow him.”

There's unlikely to be enough of a desire from the general public to fit a dropper post to their own frames to warrant brands developing a proprietary solution, and therefore, it's unlikely that we'll see mainstream adoption of dropper posts in the WorldTour. However, don't be surprised if Mohorič, his Bahrain Victorious teammates, and others who can fit them – those whose bikes currently use a round seat tube – use them for races on a more regular basis.