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No, Ethan Hayter’s dropped chain wasn’t due to ‘Shimano shifters’

But they didn't help fix it either.

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Note: This article has been updated with further information. 

It was a mechanical that brought heartbreak to Ethan Hayter’s Worlds time trial on Sunday. Just under halfway through his effort, the young Briton crested the final climb of the lap, went to shift into his oh-so-big 60-tooth big ring, and then ended up with a tangled mess. Hayter went on to finish the rest of the course with a subtly different (and arguably slower) bike, and ended a painfully close single step away from the medals. Not a great gift for the birthday boy.

As reported by Cyclingnews, a rightfully upset Hayter spoke to reporters after his race, explaining the cause of the dropped chain. “Shimano don’t make chainring shifters on the new gears,” he said. “I was trying to change chainrings and it wasn’t quite shifting, and I pressed it again and it dropped off.” 

While it doesn’t change the situation (intended) for Hayter, race footage suggests the blame should be pointed at something other than the Shimano Di2 shifters. As you can see below, Hayter tries to shift the chain, then there are multiple seconds of the chain grinding as it fails to be picked up onto the big ring, and then it jams. Throughout this process, you can see Hayter trying to use the derailleur to reset the shift, but the chain is already too far gone. 

Those familiar with Shimano Di2 will know it’s a rather robotic system. When set up correctly, a press of the button prompts the derailleur to move by a pre-configured amount. No amount of pressing or not pressing the buttons will change how it shifts – that nuance and finite control is taken away from the rider. Furthermore, Hayter’s bike was being looked after by the usual and highly experienced Ineos mechanics, and so it’s highly unlikely that the adjustment was wrong – that machine would have been dialled. 

In my opinion, the blame rests with the use of non-standard chainrings and a good dose of bad luck. Hayter was using what appear to be unbranded and perhaps custom (round-shaped) AeroCoach ARC Dual TT carbon chainrings in the 44/58T (have since found out they are 46/60T rings) size on a Shimano R9100 crank. 

A closer look at the problem ring. Also note the K-Edge chainguide which can’t offer assistance when the issue happens between the small and big chainring.

Along with offering substantially larger sizes than what Shimano offers aftermarket, these full-carbon constructed chainrings are claimed to provide an aerodynamic advantage and friction benefits. 

Now Shimano is well regarded for its front shift quality and consistency, and a big part of that is related to its stiff chainring design and intricate ramps that help pick up and guide the chain between chainrings. AeroCoach’s design does offer four pins and guides to assist with shifting, but they’d be pretty basic compared to authentic Shimano. 

Perhaps more telling though, is the following warning from AeroCoach’s website. “Cross-chaining in the inner ring (using small sprockets at the back of the cassette along whilst in the inner ring) is bad for the chain, bad for efficiency and will result in poor performance. Using an ARC DUAL inner ring in combination with the 4 smallest sprockets on the cassette is not recommended.” 

And that line from the chainring manufacturer points to one potential problem. At the time of the incident, the footage points to Hayter spinning an extremely fast cadence while in the smaller sprockets of the cassette. Add a bit of a bounce in the road and this could well result in the teeth of the big chainring getting in the way of the shifting pins, or worse, catching and jamming the chain – especially given the speed at which it was all turning. (On the other hand, and as we’ve since found out, Hayter was using Shimano’s Synchro shifting setting where it’s not possible to shift into the lowest gears of the cassette, and so, the chainline probably wasn’t to blame.)

As for why Hayter was using those carbon chainrings, that seems to be more about the goal of marginal gains and not one of bigger gear selection. Hayter’s bike appears to be unchanged from what his trade team, Ineos Grenadiers, typically take to important time trial stages. A representative from Shimano told CyclingTips that the company supplies Ineos with special 58T-sized chainrings – just not wholly sealed aerodynamic ones (or big enough) like what was used on Sunday. Hayter’s Ineos teammate and one rival of the day, Filippo Ganna, raced on Shimano chainrings.

And right there is the all-too-common trade-off associated with marginal gains in tech. All too often, those small gains introduce real-world tradeoffs. Sometimes they result in glory. Other times they leave a rider with shattered dreams. 

Update: Since publishing this article, we were given a more detailed report of what happened. From this, we can confirm that Hayter’s bike was set up using Shimano’s newer single-button shifters that rely on Shimano’s semi-automated Synchro shift. This is what Hayter meant when he said he didn’t have a shifter for the chainring. The single button shifters mean the rider only has to ever worry about whether they want a harder or easier gear, while the system is pre-configured to make that happen across the front and rear gears. The downside is that there’s no manual override or secondary bottom to shift the front derailleur quickly. 

The footage shows Hayter desperately trying to re-shift the chain back onto the chainring, but such a command was unfortunately out of his hands. The blame arguably still rests on the failed shift between chainrings, but the bad luck only extended through the inability to fix the issue on the go.

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