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WorldTour mechanics bemoan Shimano chain drops

A close up of a Shimano 12-sped chain on an 11-speed crank with a K-Edge chain keeper
Tom Pidcock's bike is fitted with 12-speed Dura-Ace, an 11-speed crank, and a K-Edge chainkeeper inside (Image credit: Josh Croxton)

With the 2022 season well and truly in full swing, there are a number of tech-related storylines coming to the fore. One of them is that many of the WorldTour teams are still using Shimano's Dura-Ace 11-speed groupset, despite the Japanese brand unveiling a newer 12-speed version in August last year. The reason, according to numerous team mechanics, is a lack of availability of the new groupset. 

The same reason was also given by teams using a mismatch of old and new, in which the new 12-speed groupset is paired with the older 11-speed chainset. It's something that nearly all teams have been seen to do at some point during the first two months of the season. 

Now, as the Classics season reaches its peak, a perhaps-related trend is making itself known: dropped chains. 

Of course, dropped chains are nothing new in pro cycling, and especially not in the Classics. It's an issue that has halted every rider at some point, no matter whether they're on Shimano, SRAM or Campagnolo, but in recent weeks they've become all the more frequent in occurrence, to the point that WorldTour mechanics from three separate Shimano-equipped teams have expressed frustration to Cyclingnews reporters. 

For example, in a 25km stretch of Gent Wevelgem, TV cameras picked up on five dropped chains in quick succession, including Marco Haller and Ryan Mullen of Bora-Hansgrohe, Lars Saugstad (Uno X), Timo Roosen (Jumbo-Visma) as well as Andre Carvalho (Cofidis). Three of them - Haller, Mullen and Roosen - were running a mismatch of 11 and 12-speed Shimano. 

At the Tour of Flanders, Kasper Asgreen (Deceuninck-QuickStep) became arguably the highest-profile victim of the issue, when his chain shipped over the top of his big chainring on the Koppenberg with a little over 40km to go. The Dane modestly brushed off the issue's relevance to his failed defence of the race, but the fact remains that the issue derailed his race at a crucial moment. He too was using a mismatched groupset.

Kasper Asgreen at the start of the Tour of Flanders

Asgreen, at the start of the Tour of Flanders, seen using 12-speed Dura-Ace with the older 11-speed crank (Image credit: Josh Croxton)

Speaking at the start of Dwars Door Vlaanderen, mechanics from various teams bemoaned the problem. Mechanics are rare to call out their equipment publicly, so unsurprisingly, all of those we spoke to were keen to maintain anonymity. 

One mechanic was particularly candid in their appraisal of using the 12-speed groupset with the 11-speed chainring, claiming the alignment is all wrong, that it becomes worse in the big ring and that it is causing chains to drop more regularly. 

Others were a little less forthright but echoed the sentiment nonetheless. One admitted a problem, but was less certain as to the cause, querying whether it was the mismatched components or simply the quality of the new 12-speed groupset as a whole. A third seemed more sure that the mismatch was at fault, due to the narrower chain used in 12-speed, but was keen to hear from other teams who have used the complete 12-speed groupset. 

The only of those running a full 12-speed setup that was available for comment was Groupama FDJ, who had no issues to speak of. 

Why are there more dropped chains?

The two potential reasons put forward by mechanics are poor alignment and narrower chains. 

Focussing on alignment, it's first worth noting that poor alignment can come in various planes, but the two that could most likely affect chain drop are the alignment of the chainset in relation to the cassette behind, and the alignment of the front derailleur with the chainrings. Given the new 12-speed cassette can fit onto the same Shimano freehub as its predecessor, the distance between the inner and outer cassette sprockets is unlikely to be different enough to cause an alignment issue in this plane. That leaves alignment of the front derailleur, which is also unlikely to be an issue since this could easily be overcome by adjusting the derailleur itself. 

That leads us onto the narrow chain then, and this is where, in our opinion, a better argument can be made. To fit 12 sprockets into the same space as 11, they need to be narrower and closer spaced, and this, in turn, necessitates a narrower chain, which Shimano has provided as part of the new 12-speed groupset. To then pair this narrow chain with chainrings designed to be used with the previous wider chain is a possible cause for incompatibility, even if only slight and/or invisible to the eye. It's safe to assume that in such a situation, shifting would feel fine until under load. 

Incidentally, even prior to the launch of the new 12-speed Dura-Ace groupset, countless consumers had experimented with using the 12-speed XTR chain on 11-speed components, and they continue to do so today. A 19-page thread exists on WeightWeenies discussing the pros and cons of doing so, and many posts report a quieter overall system due to the thinner chain having more space in the cassette, however, a few have reported issues of reduced front derailleur shift performance, incompatibility with certain chainrings, and an increase in chain drops. 

A friend of Cyclingnews who has tested the theory explained that issues arose more commonly when trying to shift under load, and so they had to be extra gentle on the pedals when shifting. It's not inconceivable that this issue would be further exaggerated under the power of a pro rider and on cobbled terrain. 

Shimano's word

Cyclingnews reached out to Shimano who clarified the following two points. In response to the question of why teams were using the 11-speed chainsets with 12-speed groupsets, Shimano's category marketing manager for road cycling, Erik van Kooten, explained that it "simply has to do with availability of product. Mainly only 172.5mm 12s power meters were delivered to our sponsored teams. The teams make do with the product they have available."

As for whether the two groupsets are officially compatible, van Kooten's answer is a hard no: "The teams are informed on compatibility: officially there is no compatibility between 12s and 11s. We do not recommend using 11s crankset with 12s components."

The caveat

We were initially curious as to whether teams were actually choosing the older crank intentionally. The new crank weighs around 50 to 70 grams more than its predecessor depending on chainring size, and while many would argue that this is insignificant enough to be ignored, it's worth reminding everyone that at the Tour de France in 2020, teams vehemently claimed their preference for mountain bike disc rotors was due to the 19 grams of weight that it saved. 

However, given the related complaints from mechanics, it's safe to conclude that as soon as Shimano can supply them, teams will be swapping straight onto the new 12-speed chainsets. 

The solution

The solution is there in plain black and white: don't mix 11 and 12-speed groupsets. However, for WorldTour mechanics needing to supply a roster of riders with two, three or four bikes each, that may be easier said than done. 

Shimano claims teams are aware of the incompatibility issue between 11 and 12-speed, but in light of its inability to supply more chainsets, mechanics are forced to improvise. Short of returning to a fully 11-speed setup, which also may not be possible due to the availability of those components, running a mismatch of old and new could be the only solution, despite not actually being a fully working solution at all. 

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Josh has been with us as Senior Tech Writer since the summer of 2019 and throughout that time he's covered everything from buyer's guides and deals to the latest tech news and reviews. On the bike, Josh has been riding and racing for over 15 years. He started out racing cross country in his teens back when 26-inch wheels and triple chainsets were still mainstream, but he found favour in road racing in his early 20s, racing at a local and national level for Team Tor 2000. He's always keen to get his hands on the newest tech, and while he enjoys a good long road race, he's much more at home in a local criterium. 

With contributions from