9 speed chain on 10 speed cassette ?
 

While digging through a couple bins of spare parts, I found I have several Shimano 9 sp chains left over from years ago, and a new 10 sp cassette, that I got for a future service my current road bike (I installed a new KMC 10-sp chain last year, soon after snagging this bike on Criagslist, but will be looking to replace both the cassette and chain at the end of this year.)
I tried Googling the question, and though i found info saying Shimano's 9, 10 and 11 sp stuff are interchangeable, I didn't find a direct answer to my question, and I suspect the wider 9sp chain will be somewhere between "less than ideal", to "completely incompatible".
Any good info is much appreciated.....

Don't do it. Don't be cheap. Put the right chain on.

Try it. If it's noisy or skips, it doesn't work and you can be the internet guru.

LOL, I literally started typing something to head off comments like these, then thought, "no, that'll be taken wrong, as well, inviting what I'm hoping to avoid" (voice of experience there). What i started to say was that I wasn't looking to do anything stupid, or "cheap out" ( turns out I also have one or two of the KMC 10-sp chains), I'm largely just curious, and hate to see these 9sp chains just gather dust, if they're actually usable. It's just a question, guys, that's all ! :D

There are too many variables to say with complete certainty. You have the parts already. Try them. If they work for you, great. You'll know soon enough if the chain doesn't shift properly on the rear. If too wide for the cassette, then it'll not fall completely into the cogs and will act as if it's trying to shift to the next gear.

External chain width frequently is not an issue for most cranksets. It is the rear cassette that usually determines the chain size. Though for optimum shifting performance, you'd want to use the chain they designed all your components around or at least one very similar.

Gift them to someone with a 9 speed (cassette), bike..

I'm sorry if I didn't answer without possibly hurting your feelings....so I'll take another try at it:

Don't do it. Don't be cheap. Put the right chain on. Don't waste your time.

You know, all you had to do was say, "no, they're not compatible", the condescending lecture doesn't serve any purpose.
BTW, what exactly is "cheap" about wanting to put into use a quality part, that I paid good money for, assuming there's no compatibility issues ? (which was all I was asking)



Not a bad suggestion, but i don't really hang with any other riders these days, plus, I do have a 9sp mtn bike (though it doesn't get nearly the use my road bike, does, and I installed a new chain and cassette late last year, so it'll be a good while before it needs a new chain).

I've never tried it but have no reason to think it would work. Rather than cutting/ messing up a new chain, why not donate it to a bike charity or coop.

I disagree. You should definitely try it. What’s the downside? Whether you succeed or fail you’ll have discovered something useful and shared it with others.

FWIW, a mechanic recently told me that some brands’ 9 and 10 speed chains are now identical. I think he was saying that new 9sp chains have the dimensions of 10sp chains. No idea if it’s true, or if I’m even properly representing his claim.

I've tried it. It doesn't work. Chain will skate over the top and not engage the cogs properly. These are Shimano chains and cassettes (105 and Ultegra).

Only one of my bikes is 10sp and when setting it up, I left the 9sp chain on to see how it would work.

It doesn't!

Thanks guys, sounds like a no-go, and that's what i wanted to know. And again, I also have a 9-speed mountain bike, so they're not just taking up space, or candidates for a Goodwill donation ! ;)

You can send the 9 speeds to me. I will use them.

Here's a thought: Maybe READ the thread first, like maybe, the post directly above yours......
"...And again, I also have a 9-speed mountain bike, so they're not just taking up space, or candidates for a Goodwill donation !"

I do not see a no in your response. Does this mean my useless, bonehead self is getting them?

"...And again, I also have a 9-speed mountain bike, so they're not just taking up space, or candidates for a Goodwill donation !"
Don't let it get you down, it'll sink in eventually.

I had some experience with this. IME 9spd chain will work IF the cassette has no single tooth steps, ie 11->12 or 12->13. In this case the protruding
rivet will hang up on the next cog and try to shift up and fall down. IF the cassette has no single tooth jumps then it will work but may be slightly
noisier. I recently used a 9spd chain on a 10spd 11-36 cassette which has no single tooth jumps and it worked fine.

When I switched to 10 speed (Campag Chorus) years ago, rather then use a Campag chain with its odd pin (can't remember what they called to, but it apparently needed a specific installation device, and the pins themselves weren't cheap) I used SRAM PC89R 9sp chains (with a breakable master link) for years. Worked perfectly. My take is - don't accept a blanket "9sp chains won't work on 10sp drivetrain" - do the experiment on a case-by-case basis. Some chains will be troublesome, some will work fine.

I've had that same experience using a 9sp Shimano chain on a 10sp Campy cassette. It works just fine. The spacing is wider on Campy than Shimano 10sp. There is a chart somewhere that shows this.

Here:Cassette Chart

You can see from the chart that 10sp Campy is only .2mm narrower than 9sp Shimano. The Shimano chain must be narrower enough that it works. 10sp Shimano is .4mm narrrower and won't work with a 9sp chain. This chart also shows why the conversion cassettes did not fully work. You ran out of room on a Shimano freehub to mount a full Campy cassette as it was wider. This changed with 11sp freehubs as Shimano had to make these wider to allow for 11 cogs, then a 10sp Campy spaced cassette would comfortably fit. I have first hand experience with this on my trainer.

So to get back to the OP, try it yourself and see. .4mm doesn't sound like a lot but it is enough to make it noisy or not work at all.

Yes, No? Yes,No?

*Some* Shimano 9 and 10 speed drivetrain components are interchangeable within limits (e.g. rear derailleurs). Unfortunately chains are not on that list, at least not reliably. A 9sp chain is almost a full millimeter wider than 10sp (6.6-6.8 mm vs 5.9 mm). So it can be too wide for the spacing of the 10sp sprockets and can start to rub against the adjacent sprockets, causing noise and shifting issues. Supposedly you can go in the other direction (10sp chain on 9sp cassette) with more success, but most people don't bother since the narrower chains are more expensive and often don't last as long.

The gap between 10 and 11 speed chains is less (< 0.4mm I think) so there's a bit of flexibility there, however in general there is very little compatibility between 11 speed groupsets and anything else. Road 11 and mountain 11 aren't even cross-compatible (except some cassettes, I think). The one exception is the newer Tiagra 10sp groups which use 11sp road actuation ratios on the rear derailleur, so you could use a Tiagra 4700 RD with 11 road speed shifters (e.g. Ultegra R8000) and an 11 speed cassette and it should work (and vice versa)