Tech FAQ: Chain width explained, compatibility queries answered

Dear Lennard,
In a prior post on VeloNews, you state that an 11-speed chain will work with 10-speed cranks, where the rest of the group is 11S.

My question is: Will an 11S chain work with a 10S drivetrain where the only 11S component is the chain?

My understanding is that the 11S chain is narrower, so wouldn’t a narrower chain wear the cassette and jockey wheels (faster/more distorted wear), with teeth designed for a wider chain bedding in to a narrower chain, or you might get chain jumps where it doesn’t drop down onto the teeth as well? And, then if you had to put a 10S chain on, due to distorted wear, there would be slop?

Or would the 11S chain work OK with a 10S group?

We’re talking Shimano 105 5700 compact front, 11-28 cassette.

Thank you,
— Barb

Dear Barb,
This is a great question, because your understanding of chain width is a common misconception that is worth clarifying.

A big part of the issue is that the bike industry is sloppy with its use of chain terminology. In traditional chain speak, “chain pitch” is the length along the chain between adjacent roller pin centers, and “chain width” is the inner spacing between link plates.

Chain pitch on all bicycle chains is 1/2-inch, since the distance between the centers of the pair of rollers on the same link plate is half an inch. So an inner/outer link pair measures one inch from the center of the roller pin on the end of the inner link to the center of the roller pin on the opposite end of the outer link. This is why you can use a one-foot ruler to determine chain wear (which results in chain elongation due to wear at the pins).

Chain width, as defined by standard methods of measuring chains, is 3/32-inch on all bicycle derailleur chains. But this is NOT the “width” people are talking about when they say, “an 11-speed chain is narrower than a 10-speed (or 9-speed or 8-speed, etc.) chain.” Yes, chains have gotten narrower as the number of rear cogs has increased in bicycle drivetrains, BUT it is only the outside width dimension that has decreased, and really, we are actually describing the length of the roller pins, which is shorter on 11-speed chains than on 10-speed chains.

When we’re discussing differences in width of differing-speed chains, we should call this dimension (the length of the roller pins) something like “outer chain width” or “chain outer width.”

The actual “chain width,” which we in the bike industry should perhaps instead call “chain inner width,” has not decreased.

Another way to say this is that the width of the rollers has stayed nominally the same through all of these changes in speeds. What has happened, however, is that the extension of the roller pins to the outside of the outer link plates has decreased. The ends of the pins are practically flush with the faces of the outer link plates on 11-speed chains, leading to much more complex methods of chain joining to not have chain breakage. Chains “break” because the chain opens up when an outer link plate has been pried off of the end of a roller pin, usually when side-loaded by the front derailleur, generally while the rider is still pushing on the pedals. I don’t think I ever heard of this happening back in the 5-speed days when I started racing, but you certainly hear about it these days.

The other change with increasing cog count is that the thickness of the chain-link plates themselves (and any bowing of the plates, which at one time was a method used to improve shifting performance) has decreased. Some lateral slop may have been taken out of chains at the pin connections, too, but some of that is still required in order for a chain to shift quickly.

So, Barb, my interpretation of your question is that you are concerned that the inner width of the chain would be different and thus would scrape material off of the sides of the teeth on the cogs and jockey wheels, or be too narrow to even drop down over them. Rest assured, that is not an issue, because 11-speed chains are still 3/32-inch-width chains, just like 5-speed chains were. And the widths of cog teeth on cassettes has also stayed essentially the same over the decades

There are other issues about using an 11S chain on a 10S system that are worth discussing, however. The spacing between front chainrings has not decreased on 11S drivetrains from 10S ones, but the spacing between cogs (of course) has. Also, the spacing between plates of rear derailleur jockey-wheel cages generally decreases with each increase in number of rear cogs.

Chains for 11-speed systems are around 5.4mm wide on the outside, vs. around 5.9mm wide for 10-speed ones, so that’s 0.25mm narrower from the center of the cog tooth to the end of the chain pin on each side. That’s not enough to likely even be noticeable in any difference in how it passes through the jockey wheel cage. It will be slightly slower getting over to the next cog or chainring during a shift, but the difference in width is so small that it’s also likely not to be noticeable. If you were to run an 11-speed chain on a 9-speed or 8-speed system, however, you would likely start noticing some decreases in shifting performance.
― Lennard

Dear Lennard,
I am thinking about upgrading my Ultegra 10-speed triple system to 11-speed. Can I keep the 10-speed front chainrings and crank on the 11-speed system?
— KC

Dear KC,
Well, no, because it’s a triple crank. You can certainly use a Shimano 10-speed double crank and chainrings with Shimano 11-speed chain, derailleurs, shifters, and cassette, however.
― Lennard

Dear Lennard,
I read the article on VeloNews about compatibility between 10- and 11-speeds but it didn’t rule out my question. I have a 10-speed Shimano setup. I want to run mid-compact, but Shimano isn’t making the rings. Can I run 11-speed rings with my 10-speed setup. Everything seems to be pushing toward 11, but I have already purchased Stages, and my TT bike is also a 10-speed. So the jump is replacing two drivetrains plus wheels since the 9-speed hubs run 10 but not 11. I have successfully run 9-speed chainrings in the 10-speed TT bike but was told it would wear out the chain faster because it is wider. Wouldn’t the 11 just be a little more narrow so not strain the chain?
— Dave

Dear Dave,
The spacing between 11-speed chainring teeth centers is not narrower than on 10-speed chainrings. In some cases, it is even a bit wider on 11-speed. So your system will perform pretty much the same as it does now if you were to replace your 10-speed chainrings with 11-speed ones.
― Lennard

Dear Lennard,
Greetings from the UK. Was searching for info on the ‘net and came across your great advice in VeloNews. Hope you don’t mind me revisiting an earlier topic re: SRAM 10- and 11-speed compatibility.

I currently ride a Cannondale CAAD 8 which I upgraded to SRAM Red 10-speed and American Classic 10-speed wheels. Unfortunately, the frame has oxidized quite badly at the cable stops so it’s time for an upgrade. Anyway I have my eye on 2015 SuperSix Evo with SRAM Rival 11-speed groupset. (The deals for a complete bike are almost as good as for a frame alone!) I’d like to swap over the wheels and as much of the SRAM Red groupset as possible but wonder what might be the optimum combination that would work.

I am not sure what might be the major sticking point(s).

I don’t think I can transfer the non-BB30 SRAM Red compact 10 chainset so:

– Will the Rival 11-speed 52-36 crankset run with the 10-speed wheelset, 10-speed chain, 10-speed Red shifters, and 10-speed Red rear mech?

– Do I need to transfer the front mech (other posts suggest the Rival will work fine)?
— Ian

Dear Ian,
That crank will work fine with your system, and there is no need to change the front derailleur (mech).
― Lennard