Condensed Answer: 10-speed chains are slightly wider than 11-speed models. Consequently, the outer plates of the chain could come in contact with the cogs surrounding the sprocket currently in use.
The results are rubbing, poor shifting, drivetrain wear, and noise. For proper operation of the drivetrain, it’s recommended to use an 11-speed chain.
Understanding Chain Width
- A chain has two widths – inner and outer. The inner width is the distance between the inner plates; the outer width is the total width of the chain.
- As the speeds on a cassette increase, the outer width of the chain gets narrower while the inner width remains the same or very close to it.
- Those dimensional changes are achieved by using thinner outer plates. For that reason, chains designed for more speeds are weaker when all other parameters (material, production quality…etc.) are equal.
- Chains designed for more speeds are narrower because cassettes get denser with each gear increase.
- It’s logical to think that extra gears equal a notably wider cassette, but this isn’t the case. In order to make a hub compatible with as many cassettes as possible, manufacturers do their best to fit more and more sprockets within the same dimensions.
- This is achieved by slightly reducing the distance between each cog. In addition, the sprockets get ever so slightly thinner too.
- The smaller distance between the cogs makes it impossible to use chains designed for fewer speeds than the number of cogs on the cassette.
The table below contains the inner and outer width of 7-11-speed chains:
| 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 |
The conclusion is that 10-speed cassettes are 0.38mm wider than 11-speed models. (The inner width is the same.) The difference is substantial enough to make for a less than ideal shifting experience when using a wider-than-planned chain.
Cassette Characteristics
The next table shows the width of various cassettes and the gap between the sprockets.
Note how the gap decreases as the number of speeds increases.
| Brand & Number of Speeds | Cassette Width | Distance Between Sprokets |
| Shimano 7-speed (MTB) | 32.4mm | 2.65mm |
| SRAM 7-speed (MTB) | 32.0 mm | 3.15mm |
| Shimano 8-speed (MTB) | 35.4mm | 3mm |
| SRAM 8-speed (MTB) | 35.4mm | 3mm |
| Shimano 9-speed (MTB) | 36.5mm | 2.56mm |
| SRAM 9-speed (MTB) | 36.5mm | 2.54mm |
| Shimano 10-speed (MTB) | 37.2mm | 2.35mm |
| SRAM 10-speed (MTB) | 37.2mm | 2.35mm |
| Campagnolo 10-speed | 38.8mm | 2.42mm |
| Shimano 11-speed (MTB) | 39mm | 2.15mm |
| Campagnolo 11-speed | 38.8mm | 2.25mm |
As you can see, 11-speed cassettes are slightly wider overall while having less space between the cogs. Those properties necessitate the use of a narrower chain too.
FAQ: What about using an 11-speed chain in conjunction with a 10-speed cassette?
An 11-speed chain is narrower and doesn’t cause rubbing when installed on a 10-speed drivetrain. The shifting may have a small delay due to the extra travel that the chain has to cover. However, the delay will more than likely be unnoticeable. (read more)
