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In most cases, a 10-speed chain will operate just fine with a 9-speed cassette because it’s slim enough to move up and down the rear cogs without rubbing or skipping.  

More Speeds = Narrower Chain 

Extra speeds require the use of cassettes with more cogs. To fit the additional cogs on the same hub, the cassettes have to be condensed. 

For example, 8,9,10 and 11-speed MTB Shimano cassettes are designed to operate on hubs with the same spacings.

To accomplish this task, the distance between each individual cog diminishes as the number of gears increases.  

The outer width of the chain decreases to reflect the higher number of gears too. If the chain’s dimensions are kept the same, it won’t “bite” properly and will skip. Hence why manufacturers make chains according to the number of speeds. 

Note: The inner/roller width of the chain reports no or minimal reduction between different speeds because otherwise, the sprockets would have to get substantially thinner. Since ultra-thin cogs would be weaker and less durable, the inner width of the chain is kept as wide as possible. 

But in order for the chain to get narrower something has to give. The only options left to play with are the outer links and the pins.

In consequence, the outer links of multi-speed chains are thinner, and the pins are more in line with the plates.

The end result is a narrower but also weaker chain with a shorter lifespan.  

Chain Spacing  

The table below shows the dimensions of a chain according to the number of speeds it is designed for. The values are estimates and vary from one manufacturer to the other. 

10-speed chains have the same inner/roller width as 9-speed chains while being narrower.

Therefore, a 10-speed chain meets the compatibility requirements because it has enough inner space for a 9-speed sprocket and doesn’t cause rubbing due to its slimmer profile.

Cassette Characteristics 

The table below shows the width of various cassettes and the space between the sprockets.

Note how the inner gaps decrease as the number of speeds increases. 

What Are the Downsides of Combining a 10-speed Chain With a 9-speed Cassette? 

There are three main downsides: 

Durability

A greater number of speeds equals a thinner chain with a shorter lifespan.

In consequence, a 7-speed chain can last a surprising amount of time whereas a 10-speed chain needs more frequent replacement despite being more expensive.  

Shifting speed 

The ramps of the cogs will have a harder time picking up the chain due to its narrower profile. The shifting won’t be as optimal as possible and may even feel a bit slower.  

Price 

10-speed chains tend to be more pricy than chains designed for fewer speeds. One of the reasons for that is that 10-speed drivetrains are found on intermediate and advanced bicycles.

This makes 10-speed chains part of a premium package, unlike 6,7,8-speed chains which are the norm for all kinds of entry-level bikes. 

When you add the durability factor, the expenses raise even more because you will have to replace the chain more frequently. 

What Are the Advantages of Using a 10-speed Chain with a 9-Speed Cassette? 

Less Chain Rubbing 

Obviously, a 9-speed chain is an optimal solution for a 9-speed cassette. If this wasn’t the case, there wouldn’t be a need to produce 9-speed chains.

That said, some people use 10-speed chains with cassettes designed for fewer speeds on purpose. The main goal is to reduce the rubbing of the chain against the front derailleur’s cage. (The 10-speed chain reduces the chances of rubbing because it’s slimmer.) 

Lighter Weight 

A 10-speed chain requires less material and is, therefore, lighter than a 9-speed chain.  

Below is a table comparing the weight of 10 and 9-speed chains: 

Conclusion: 10-speed chains are only about 10% lighter than 9-speed chains. It’s arguable whether even pro-cyclists can notice such a difference.  

More Flexibility 

Some people say that a 10-speed chain is more flexible than chains designed for fewer speeds. The flexibility is considered beneficial during cross chaining. 

Cross chaining is the result of extreme gear combinations – a small chainring combined with a small cog or a big chainring working with a big cog at the back.

In both cases, the chain looks “crossed” rather than straight when observed from above.

According to this theory, a 10-speed chain tolerates cross chaining better thanks to the extra flexibility and gives you an additional quick shift at the back before having to change the chainrings. 

Can a 9-speed Crankset Work With a 10-speed Chain? 

The thickness of modern 9 and 10-speed chainrings is about 2mm.

The internal/roller width of 9 and 10-speed chains is the same – 2.18mm.  

The only difference is the spacing of the chainrings. 9 and 10-speed chainrings aren’t spaced the same way, but the differences aren’t humongous.

In most situations, the set-up works. The only way to know with certainty, however, is to experiment.  

Frequently Asked Questions 

Is a 9-speed chain compatible with a 10-speed cassette? 

In some cases, a 9-speed chain may work just fine with a 10-speed cassette.

In general, however, running a chain designed for fewer speeds than the cassette is not considered a good practice.  

The 9-speed chain is wider and can rub and skip when combined with a 10-speed cassette.

Will a 10-speed chain work on an 11-speed cassette? 

In this case, the same principle applies – a chain designed for fewer speeds than the cassette could cause problems.

A 10-speed chain is too wide for an 11-speed cassette and will likely shift poorly regardless of how much you play with the barrel adjuster because the chain’s outer links will be too close to the ramps of the cogs.

The end result will be “premature” shifting. Also, the bike could become nosier as the chain will be rubbing against the cogs.  

Having said that, there may be some chain and cassette combinations that work just fine. If you already have the necessary components, you can experiment. In general, however, it’s best to use an 11-speed chain. 

The opposite combination (11-speed chain + 10-speed cassette) is possible because the 11-speed chain is narrower and won’t cause rubbing.  

What tools do I need to install a 10-speed chain? 

You will need a chain breaker to open the chain and size it appropriately. Make sure that the chain breaker supports a 10-speed chain before buying it.  

For convenience, you could also purchase a quick link which will make it easier to remove the chain and clean it during your maintenance routine.  

Some chain link models are designed for single use only. This means that you will have to replace them every time. A more economical solution is to go for re-usable links.  

Note: You could consider getting a set of pliers for chain link removal too. However, those aren’t mandatory. A set of regular thin pliers could work. Personally, I like to use thick U-shaped steel wire or the small pliers of my Leatherman PS4 squirt mini-tool. 

Will a 10-speed cassette fit on a 9-speed hub? 

8,9,10 and 11-speed MTB cassettes are very close in width (table above) and can fit on the same freehub body as long as the hub isn’t part of the early 10-speed era. (at the time, the hub width was different)  

8,9 and 10 road cassettes can also be installed on the same road hub. 11-speed road cassettes, however, require an 11-speed hub in order to get the derailleur away from the spokes. 

Why? Because the lowest gear of a road bike is higher than that of an MTB. For instance, a road bike’s lowest gear may be 30-tooth whereas that of an MTB may reach 50.  

The larger MTB cog results in a greater offset and pushes the derailleur away from the cogs. The smaller road cassette, on the other hand, gets the derailleur dangerously close to the spokes. To fight this problem, 11-speed road hubs have a wider body.