Nerd Alert: Dropped chains in pro racing

Perhaps a question for a future Nerd Alert segment, but what is happening with all the dropped chains in racing recently?

In MSR several riders dropped their chains in more or less critical places. Mohoric got lucky and recovered it, but riders like Sagan and Valgren were taken out of in critical places (Sagan just before the Cipressa and Valgren on the decent from Poggio).

And again in E3 and Gent-Wevelgem there were a lot of images of riders standing by the side of the road with jammed chains. It was also discussed by the commentators on the Danish Eurosport channel.

I have heard mentions that the new 12-speed Dura-Ace os the culprit but is there facts to back this up (on Sunday at least one of the riders were on Campagnolo)?

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Not one reply? Electronic shifting mafia make an offer to the CT forum admins?

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I think there is no generalization to be made. In Sagan’s case you could clearly see from the images that he had a piece of metal stuck in the rear derailleur lower jockey wheel and that he wasn’t able from his position to see it, so chain mobility was totally fucked up by an external object.

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Yeah, seemed like more drops than usual at G-W, but not sure if it’s a DA issue.Pretty sure I saw one of the Wanty guys lose their chain, and I doubt they are on 12-sp, and I believe Sagan is still on 11 sp as well? Might be a question of alignment of the chains catchers with the narrow chain? It can slip down past them but not be brought back up?

We’re in the purely hypothetical here. Hopefully the nerd alert covers it off with a pro mechanic in the next week or two.

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Mechanical Campag for the win! :rofl:

In all seriousness, it would be interesting to hear an informed perspective here. I’m aware there’s some 2nd hand chat doing the rounds that chain drop (and chain throw) is more of a problem on the new Di2 than the old, and (n=1) one early adopter lost his chain outside the big ring twice during our ride on Sunday, though of course that could equally well just be setup issues, and internet/message board/cafe ride gossip does not = fact.

Was it Cancellara who always insisted on mechanical for the classics? Could be wrong, but I seem to recall that. I know Sagan always does for Paris-Roubaix.

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IIRC, Cancellara didn’t like the lack of tactile feedback of the di2 shifters on cobbles.

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Yes I am curious about what the Nerds think as well. I cannot believe how often chains are dropped in pro-racing. I raced for 20 years at amateur level in the UK and I cannot think of a time when i dropped a chain and had to get off… This was along time ago… (last road race 2007!!). I have Ultegra 8000 on my two bikes (one gravel one road) and ride about 16,000 km a year and again cannot remember ever dropping a chain on this group-set. Sure it must of happened but it is a once in a blue moon event. Clearly riding pro level races is a different kettle of fish, but does more power and speed really effect chain security?? Also it seems to happen in places where I cannot imagine the pros would be shifting out of the big ring??
I have never ridden an electronic group-set so can’t comment on that, but I would speculate that it would make it harder to get the chain back on with the front mech as you would not be able to judge the pressure you apply to the chain to pick it back up?

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At the risk of starting a (sort of) OT debate, it’s a fairly established problem with SRAM AXS. Apparently Rival is a bit better, but I have no personal experience. That said, I don’t recall seeing it happen much in women’s racing, where there are far more riders on SRAM than on the men’s tour.

With the old Di2, it used to be very, very rare. The recent G-W was the only time I’ve ever seen it with EPS.

I could speculate that because the movement of the FD is automated (you can’t vary the force, as @Gavin notes) it’s a bit more of a risk with electronic, especially if you’re a bit clumsy with the shift, but it’s only speculation. In a decade on mechanical Campag, though, I can only recall 3-4 instances of dropping a chain, and I average that in less than 2 months with AXS!

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Makes me wonder why for the cobbled classics (and anything else super rough) the Shimano lot aren’t mixing DA and GRX. Sure it’s only 11 speed but who cares how many gears you’ve got if your chain isn’t on!

Guess this might be an area where SRAM have the advantage with 12speed 1x for the road, can fit a lightweight guide on the front and things should be pretty secure. It has won Roubaix so is pretty proven now.

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What part(s) of GRX do you think they should use and what technologies does it have to prevent a dropped chain that is not included in DA?

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Clutched mech for the rougher stages.

Obviously won’t help with front shifting issues and Shimano doesn’t have the range for 1x racing but a small improvement is still an improvement.

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Dropping chains has always been a thing in all facets of racing, from your amateur cat 3/4 rr to the tour. Probably has to do with rushing shifts at high power, elevated speeds over rough surfaces, and higher likelihood of things getting bent damaged in transport. I think the pros who used mechanical for the classics liked it as others have said for the tactile feedback, because earlier Di2 was prone to going into crash mode at the speeds they’d ride the cobbles (keep in mind these guys are doing like 50kph over cobble stones) and also because they like being able to massage it into gear if the hanger gets bent in an inevitable crash and the team car isn’t around.

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Gotcha…I thought you were talking about a GRX crank setup.

Other than a few anecdotes, I have not really noticed anything in terms of dropped chains as a result of being in cobbles or gravel. For example, a clutched rear would not have prevented Mohoric’s dropped chain in MSR.

The new Classified rear hub is really intriguing to me. Could that + 1x chainring with a narrow-wide tooth profile + clutch RD be the answer to dropped chains? I still haven’t seen efficiency tests on the Classified hub.

The clutch in the RD makes a lot of difference according to my experience with regards to the likelihood of dropping the chain from a chainring as it massively reduces the bouncing of the chain.

You obviously still have to nail the FD adjustment and the adjustment of a (mandatory for pro racing IMHO) chain keeper in order to completely prevent it.

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Admittedly both my clutched mechs are on narrow wide rings but neither of them (alu gravel & 140mm MTB) have dropped a chain in years.

I know there’s a loss in efficiency for clutch on but less flapping and lower dropping chance seems a good trade off.

Clearly I’m not a pro but they often have inertia to not change because of traditions.

You’d think improved chances of finishing with clutches or tubeless or whatever would be worth a shot. (End going on a tangent!)

Maybe it’s because a lot of the pros are running the older 9150 cranksets with the 9200 stuff. It definitely works in the bike stand and cruising around but I wonder if there is an issue with shifting under extreme load with the 9150 cranks and 9250 derailluers and chain?

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The clutch Ultegra rear Der has been pretty good for me on a 2X gravel setup. I am also using Absolute Black Ovals (Which of course make everything worse in terms of adjustment and retention) but so far no issues with chain loss.

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Likely more due to the chainrings vs. the rear der. I have been running 1x Ultegra mechanical for a few years (non-clutch RD) and haven’t dropped a chain, including doing The Rift in Iceland which had some really brutal gravel / washboard segments.

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pure speculation fwiw. narrower chains + more extreme chain angles due to (# of cogs + wheel dish (disk brakes) + shorter stays) + maybe di2 trimming both derailleurs a the same time. it all moves tolerances the wrong direction.

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