Hey, I m running an indoor trainer with a 12s Sram cassette. My girlfriend started biking and wants to use it too. Her bike is equipped with an Ultegra R8000 11s groupset. I m pretty sure a 11s chain wouldn’t work with the cassette. So my idea was, to change her chain from 11s to 12s Shimano chain. I guess for ERG mode this should be fine, but will this have a negative effect on the outdoor shifting performance with the 11s chainrings and cassette?
I run 12 speed Shimano chains on all my bikes, including the ones that are 11sp groupsets.
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Erg mode might be fine, might not. You may have to turn the barrel adjuster to get it perfectly aligned to a specific cog
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This just seems like a bad idea to me. Specifically running 12s chain on 11s gears seems likely to suffer from bad shifting and wear.
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I’d be super nervous to ride a bike with a mismatch considering you want a full range of gear use.
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That’s compared to the alternative of a mismatch on the trainer where you really only need one gear to work decently for ERG use
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- I’d at least suggest trying her bike on the trainer with the SRAM 12s cassette in ERG since it sounds like you haven’t done so already. I suspect there will be a gear that works with minimal noise and seems like the safer oil/water mix than your proposal.
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Note that if you run SRAM AXS 12sp components, you’re supposed to use SRAM flat-top chains. SRAM AXS is not cross-compatible with non AXS components. It may work, especially in ERG mode, but it will likely cause extra wear.
But isn’t a 11s chain to wide to fit a 12s cassette?
I have a flat top chain and never planned to change that.
I don’t think it’s enough to matter. I did some searching but can’t find the exact dimensions. But considering the widths likely in play, I think the 11s chain on the 12s cassette is the “safer” option.
It’s free and presumably a 5-minute test for you to try since everything is already in place, so I suggest starting there.
Good point. I guess I ll do that
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I can’t speak to running a 12 speed Shimano chain on a Sram cassette.
But can confirm that it is NO PROBLEM to run a 12 speed Shimano chain on an 11 speed Shimano cassette. I do it on all of my 11 speed bikes. Many people prefer the 12 speed chain performance to the 11 speed chain. There is an entire thread on Weightweenies where people share their experiences. https://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=159526
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Admittedly I just did a quick skim of the earliest and latest pages, but I see some “works good” along with some “the skinny chain gets sticky on the RD pulley wheels” to not call that a 100% green light. It’s enough that I still stick with my thought that having the imperfect mismatch on the trainer still seems the best compromise (assuming it works per the recommended test).
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Disagree. Go the other way. Tons of people use 12sp chains on 11sp drivetrains (check out the Weight Weenies thread). It’s not uncommon. I would not want to use a wider chain on a narrow cassette. You’ll get a lot more rubbing. I switched over to use 12sp chains on all my 11sp bikes a few years back (was using the XTR chain). If anything, it’s quieter and easier to index.
Edit: Didn’t realize you linked the WW thread. I think there’s another thread with people running the 12sp chain with good results, I’ll see if I can find it.
Im not fortunate enough to have 12 sp but my last bike was 10sp but I ran an 11sp chain on it for at a guess half of its 40,000 miles. I suspect she’ll be fine with a 12 spd chain. Chains are identical on the inside and its only the side plates which are thinner for fitting into a more tightly packed cassette.
- I am not certain that is universal. It’s part of what I have been searching for and have some incomplete info that sheds at least some light.
Looking at chain specs for outside width:
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I am not sure if this is purely plate thickness or if the inner gap and roller are a tighter space too.
If we look at Sprocket (Cog) Thickness changes in this chart:
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I suspect that since the Cog thickness gets thinner, actual gap between the chain also gets thinner in likely an equal measure (or something close).
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I say that because it’s hard to imagine them making cogs thinner and leaving the inner chain width wider. It would allow the chain more “wiggle room” on the cog which seems the opposite of what leads to snappy and accurate shifting.
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But this is speculation based upon incomplete info, missing 12s info specifically while 10s-11s is 1.6mm. I thought I had found a different site with actual inner chain width specs, but am failing to find it right now.
ETA: Found the other resource I had in mind. It has some outer and inner chain width info, but MTB only from what I see now:
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This indicates the chain inner width matches for MTB from 9-12s. It may hold for road too, but I am still working to find that info.
Their Road Cassette info seems to mostly parallel the MTB chain info:
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But sadly missing the Shimano 12s Road.
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I don’t know how good this site is for tech data but it claims to have 12 speed data:
Bicycle drive chain standard dimensions | BikeGremlin
And whilst the late great Sheldon is I think saying similar, he doesn’t specifically reference internal width (just external and thinner plates) and he starts his text:
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I can’t swear to their accuracy either, but I already linked that page at the start of my post above. I just shared a different part of it with their chart vs the text you snagged.
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That text you clipped seems to parallel the O-bike info I found later and added to that same post above. So it looks like the 9-12s chains match inner spacing.
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Any update on this? Same issue here, with AXS 2x12 Groupo on the way and Kickr Core with Shimano 11spd cassette, and girlfriend on Shimano ride. Only use ERG mode.
Yes, equipped my girlfriends bike with a 12s Shimano chain. Works perfect with the 11s cassette and no problem with the 12s sram cassette on the trainer in erg mode. Way to go. the 11s chain kindda worked but was noisy with the 12s sram cassette.
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