Unless the 12-speed in question has a highly custom architecture and is designed for a very specific drivetrain, it should operate on an acceptable level with an 11-speed chainring.
The dimensions of 11 and 12-speed chains are very close. 12-speed chains have the same inner width and are only slightly narrower externally.
That said, mixing 12-speed chains with 11-speed chainrings increases the chance of dropping a chain.
How much? Not a lot, but sufficiently to mention the possibility.
Inner and Outer Chain Width
Bicycle chains are characterized by two widths – inner and outer.
The inner width is the distance between the inner plates and is influenced by the thickness of the rear cog(s) and that of the chainring(s).
The outer width is the distance between the outer plates and is dependent on the spacing between the cogs and the chainrings.
More Gears = Thinner Chain
As the number of gears climbs, chains get thinner/narrower. This is achieved by thinning out the external plates.
Why? The inner chain width has to stay almost the same for all gears because the thickness of the sprockets and chainrings is fairly consistent (approx. 1.6mm).
However, cassettes designed for more gears get progressively “denser” because the width of the hub doesn’t increase much with each consecutive gear. (The goal is to keep the same hub compatible with multiple cassettes.)
The reduced proximity between the sprockets requires a thinner chain. The outer width discrepancy between chains that are 1 gear within each other is small, but the gap gets significant as the number of gears climbs.
The table below contains the inner and outer widths of most bike chains:
| NUMBER OF SPEEDS | INNER/ROLLER WIDTH | OUTER WIDTH |
|---|---|---|
| 7 | 2.38mm | 7.3mm (Shimano), 7.1mm (SRAM) |
| 8 | 2.38mm | 7.3mm (Shimano), 7.1mm (SRAM) |
| 9 | 2.18mm | 6.5-7mm |
| 10 | 2.18mm | 5.88-6mm |
| 11 | 2.18mm | 5.5-5.6mm |
| 12 | 2.18mm | 5.3mm |
Conclusions: The inner width of 11 and 12-speed chains is the same. The outer width of 12-speed chains is 0.2 to 0.3mm narrower. The outer width discrepancy is present but still too small to create major incompatibility problems.
Potential Problems
- Insufficient Derailleur Travel
If you’re using an 11-speed front derailleur, it may have an ever so slightly insufficient “throw” for snappy shifting to take place due to the extra distance that it has to cover.
One of the ways to battle this issue is to move the derailleur’s “resting position” ever so slightly away from the frame via the limit screws. The downside is that the new distance could cause rubbing between the derailleur’s cage and the chain in more extreme gear combinations.
- Architectural Incompatibilities
Some 12-speed chains such as Shimano’s new HyperGlide+ line are designed specifically for 12-speed chainrings.
The length and width of the links as well as their shape will not fully agree with standard 11-speed chainrings. That doesn’t mean that those chains will fail when combined with an 11-speed chainring, but the chance of less-than-ideal performance is higher.
- Incompatibility Between Brands
It’s also possible to experience some incompatibility when mixing brands.
Combinations That Have Been Known To Work
Below is a list of 12-speed chains and 11-speed cranks/chainrings that have been known to work to a satisfactory degree:
- Ultegra 12 chains + Sram Red Exogram GXP
- 12-speed Di2 + Ultegra 11-speed chainring
Did You Know That….?
During the World Tour Pro competition in 2022, there was a shortage of 12-speed cranks. As a result, many professional cyclists had to use their older 11-speed cranks and chainrings in conjunction with 12-speed chains and cassettes.
(11-speed chains cannot operate with a 12-speed cassette because they are too wide and rub against the adjacent cogs.)
Unfortunately, a notable amount of riders dropped a chain. According to the mechanics, the problem came from the mismatched chain and chainrings. (You can read the story in far more detail here.)
One can therefore conclude that it’s bad to mix a 12-speed chain with 11-speed chainrings, but that wouldn’t be exactly accurate.
First, pro cyclists have experienced dropped chains even when the components match perfectly.
Second, more often than not, the chain drops when the rider shifts aggressively under load – an action that isn’t recommended to being with and unlikely to happen during standard commuting.
Let’s face it. Most of us aren’t professional cyclists, and we are rarely as close to our limits as they are.
Third, even though the combination was not ideal, it didn’t stop the mechanics from signing on it. In other words, the risk wasn’t high enough to stop the mixture.
FAQ: Will a 12-speed chain operate well with an 11-speed cassette?
In general, yes. 12-speed chains are slightly narrower than 11-speed chains but have the same inner width. Consequently, they can fit on an 11-speed cassette. The main issues would be ever so slightly delayed shifting. It’s questionable whether this is even noticeable (read more).
