Condensed answer: KMC’s 12-speed chains are designed for 12-speed drivetrains of any kind and are therefore fully compatible with SRAM Eagle’s cassette and rear derailleur.
A List of KMC Chains Compatible With SRAM Eagle
SRAM Eagle is a 12-speed MTB groupset. Consequently, it requires a 12-speed chain. A chain of fewer speeds cannot be used because it will be too wide and will rub against the surrounding cogs. (I will explain why further down the article.)
For that reason, only 12-speed KMC chains fall into the compatible list:
- DLC12
DLC12 chains have a Titanium Carbon Nitride (TiCN) coating. TiCN is a hard ceramic material that slows down the external wear of the chain.
Other features of the chain are outer and inner plate chamfering. In simpler words, the plates of the chain are shaped in a way that makes shifting easy and accurate. The chain comes with 126 links.
- X12
X12 chains have very strong pins and chamfered plates facilitating shifting. They are also known as KMC’s “golden” chains as the main color is gold.
- X12 EPT
The X12 EPT chain is part of KMC’s EcoProTeQ series and has an anti-rust coating that significantly reduces the chances of getting a rusted chain. Just like the other models, this chain has chamfered plates for smooth and accurate shifting.
Note: KMC has two more 12-speed chains (e12 Turbo and e12 Turbo EPT). Those models are designed solely for e-bikes and are therefore not compatible with a standard 12-speed drivetrain.
Chain and Groupset Compatibility Explained In ELI5 Style
- The chain interacts only with the cassette and the chainring. If the three components can “agree with each other” and work in peace then the chain can be integrated into the said drivetrain. The shifter and the derailleur(s) do not care about the chain.
- Chains have an inner and outer width. The inner width is the distance between the inner plates; the outer width is the distance between the external plates.
- The inner width of a chain decreases when going from 8 to 9+ speeds but stays the same across 9/10/11/12 speeds.
The table below contains the inner and outer widths of standard bicycle 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 |
As shown in the table, 9/10/11/12 speed chains have the same (2.18mm) inner width. However, the outer width gets progressively narrower.
- The outer width decreases because cassettes get denser with each extra gear. Or in other words, the space between the cogs gets smaller. Why? The goal is to fit as many cassettes as possible on a rear hub without making it wider. This engineering facilitates future upgrades.
- Since the inner width remains similar or the same (because the thickness of the cassette sprockets doesn’t change much either), the only way to acquire a narrow chain is to thin out the outer plates.
- Ideally, the chain and the cassette should be designed for the same number of gears. If the chain is designed for fewer speeds, it will be too wide and will therefore rub against the surrounding cogs. The shifting experience will be poor, to say the least.
- If the chain is designed for one extra gear than what we find on the cassette, the chain can be used. For instance, it’s possible to use an 11-speed chain on a 10-speed cassette.
FAQ: What would happen if I use a chain that isn’t on the recommended list?
If the chain isn’t on the recommended list, it will not work well with SRAM Eagle.
SRAM Eagle is a very expensive groupset. It doesn’t make financial sense to experiment with chains that aren’t designed for it.
FAQ: What are the official chains that SRAM recommends for pairing with SRAM Eagle?
The officially recommended chains for SRAM Eagle are GX Eagle, X01 Eagle, and XX1 Eagle.
