Condensed Answer:
A Dura-Ace chain is compatible with Ultegra drivetrains when each is designed for the same number of gears.
In other words, it’s recommended to use an 11-speed chain with 11-speed drivetrains and a 12-speed unit with 12-seed systems.
Chain Width Is Speed Specific
The number of gears that a chain is designed for has a direct influence on the chain’s width.
Bicycle chains have two widths – outer and inner. The inner width represents the distance between the inner plates; the outer width indicates the distance between the outer plates or the total width of the chain.
As the number of speeds on a cassette increases, the inner width changes very little, but the outer width decreases significantly.
The reason for this engineering starts at the rear hub. To fit a variety of cassettes on the same hubs, manufacturers “squish” the cassettes as the number of cogs augments.
The thickness of each sprocket is kept almost the same (there’s a small decrease), but the distance between each sprocket gets progressively smaller with each extra gear.
(By the way, the center-to-center distance between two adjacent cogs is known as cog pitch and is the officially used term to indicate cog spacing.)
The reduced space between the sprockets requires a thinner chain. Otherwise, the chain would rub against the cogs surrounding it.
Since the overall thickness of the cogs is relatively the same, the width decrease is achieved by thinning out the outer plates of the chain.
For that reason, chains designed for more cogs are weaker when all other parameters (quality, materials…etc.) are equal.
The table below shows how the inner and outer widths of chains vary according to the number of sprockets at the back.
| Number of Speeds | Inner/Roller Width | Outer width | Sprocket Thickness |
| 7 | 2.38mm | 7.3mm (Shimano), 7.1mm (SRAM) | 1.85mm |
| 8 | 2.38mm | 7.3mm (Shimano), 7.1mm (SRAM) | 1.85mm |
| 9 | 2.18mm | 6.5-7mm | 1.78mm |
| 10 | 2.18mm | 5.88-6mm | 1.6mm |
| 11 | 2.18mm | 5.5-5.6mm | 1.6mm |
As you can see, the inner width of 10 and 11-speed chains is the same, but the outer width of 11-speed chains is 0.3-0.4mm narrower.
For that reason, it’s recommended to use an 11-speed chain for 11-speed cassettes and a 10-speed chain for 10-speed cassettes.
If you try to use a 10-speed chain on an 11-speed cassette, the combination will not work because the chain will be too wide and will cause rubbing. The other option (11-speed chain + 10-speed cassette) is more viable because 11-speed chains are narrower and can fit just fine. You can read more on the topic here.
Recommended post: Can You Use a 12-Speed Chain on an 11-Speed Cassette?
FAQ: What are the advantages of using a Dura-Ace chain with an Ultegra drivetrain?
Dura-Ace chains are slightly lighter. That said, the difference is non-perceivable and matters only when one is trying to build the lightest possible bicycle.
The main practical advantage is that you have another option to choose from. If you have access to a Dura-Ace chain that fits and nothing else is available, you can use it.
