There was an interesting thread in the Bikepacking group on another site about chain strength and people's opinions were all over the map. I did a little research and came to my own conclusions. Since a lot of people here are concerned with durability, I figured I'd share.
Note: this is not a claim of a "best" drivetrain or a rejection of older 7-10 speed drivetrains. It's just a conversation about whether there is, if any, a durability factor between different speeds. My opinion is that it's not significant.
Here's what I wrote for the group:
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There was a discussion in the group last week about chain durability, and the common logic (not surprisingly) is that an 8/9-speed chain is stronger than a 10/11-speed chain.
Not so!
The logic likely stems from the 8-speed chain looking almost twice as thick as an 11-speed chain. They look stronger, therefore they must be stronger. But the industry learns fast, and chains have been getting a lot stronger through subsequent generations thanks to stronger materials, stronger coatings, tighter manufacturing tolerances, and lots of other minute factors.
The end result is a chain that lasts much longer, and isn't any more likely to break in a crash. If you hit a rock hard enough to break/bend a 1.6mm chain link, a 2mm chain link isn't likely to survive either.
It doesn't help that there's always anecdotal evidence. "I broke an 11-speed chain, thus, 11-speed is weaker." There's been no radical shift away from 11-speed in the racing world in any discipline- even downhill bikes are using 11-speed chains. If chain failure was rote with the 11-speed system, it'd be phased out, but instead, things are getting even narrower with new drivetrains like SRAM Eagle.
But don't take my word for it; here's some real-world testing and answers. Bikerumor did a 2-year, thousands-of-miles test on six Shimano XT-equipped bikes with XT drivetrains. Three of them were on 9-speed chains, and the other 3 were on 10-speed chains. The 10-speed chains outlasted the 9-speed by a factor of 500 miles.
Bikerumor Shimano Chainwear Challenge: The Results - Bikerumor
Here's a good quote from the article:
Ok, but that's not the whole story. There are a few drawbacks to the narrower chains. Tooth profiles on chairings have gotten smaller, but the distances people ride have remained about the same, so you're looking at a lower tooth life on your rings and/or cassettes.
Breaking a Chain
Chains have a breaking strength of something to the tune of 4,000nm, far more strength than any of us can put out. But, chains do break. Twisting, rock strikes, or corrosion are the main reasons. So, if you're really concerned about chain longevity:
- Ride carefully and avoid rock strikes, fallen logs, sticks, rebar, etc.
- Get a bash guard for your crankset
- Keep your drivetrain well maintained and well-adjusted for precision during shifting
- Don't shift under load
- Keep everything lubricated and clean
These are the real factors of chain durability. If you're reverting back to 8-speed so you can neglect your system, you're in for a bad time. With the minuscule measurements we're talking about between 8-speed and 11-speed, it's my firm opinion that chain durability is constant enough that it can safely be ignored. If 11-speed is the drivetrain you want for bikepacking, go for it and don't look back.
People who use 11-speed drivetrains:
- Lael Wilcox, Women's Tour Divide Record Holder- Sram X01 11-speed
- Mike Hall, Men's Tour Divide Record Holder- Shimano XTR 11-speed
Hope this is useful! Would love to get a discussion going- tell me why I'm wrong!
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