[wild]

I think the 9spd chain will last longer from the bikes I have, but that might be caused by my cross chaining. my bike has Tiagra brifters, Tiagra front derailer and a Deore XT M771 rear derailer with 50/39/30 11/34 cassette.
I like this setup, I find the 30x34 all I can spin.
My ¢¢

[i12ride]

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[cderalow]

Originally Posted by i12ride

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The difference in ring thickness is barely discernible.

[i12ride]

If it doesn't matter then why would there be seperate chains for 8,9 & 10 speed?

[cderalow]

Originally Posted by i12ride

If it doesn't matter then why would there be seperate chains for 8,9 & 10 speed?

because if manufacturers claim they're incompatible, then they're forcing you to buy a new one.

the difference between 8&9 speed chainring & cog thickness is 0.02mm it becomes more substantial between 8/9 & 10 speeds as there's a 0.2mm difference.

what realistically makes chains different is the outside measured width, the result of thinner joining plates

[i12ride]

Originally Posted by cderalow

what realistically makes chains different is the outside measured width, the result of thinner joining plates

Seems like we've gone full circle back to "chain width".

[davereo]

The width of the chain is not going to be compatible with the cassette. The cassette cogs and chain will interfere with one another. The cogs on the rear are spread out on the same size freewheel hub. An 8 speed chain will not fit properly on a 9 or 10 speed cassette being that it is too wide and will come into contact with the corresponding cogs on either side of the one it is riding on.

You can use a 10 speed crank on a 9 speed bike. You need to match your chain to your cassette. To eliminate interferance and enable the ramping on the cogs to properly snag your chain and guide it onto the proper cog selected.

If you take the .2mm and multiply it by 10 you would have an error of 2mm over the distance of the cassette. The width of the chain is important.

[cderalow]

Originally Posted by i12ride

Seems like we've gone full circle back to "chain width".

Originally Posted by davereo

The width of the chain is not going to be compatible with the cassette. The cassette cogs and chain will interfere with one another. The cogs on the rear are spread out on the same size freewheel hub. An 8 speed chain will not fit properly on a 9 or 10 speed cassette being that it is too wide and will come into contact with the corresponding cogs on either side of the one it is riding on.

You can use a 10 speed crank on a 9 speed bike. You need to match your chain to your cassette. To eliminate interferance and enable the ramping on the cogs to properly snag your chain and guide it onto the proper cog selected.

If you take the .2mm and multiply it by 10 you would have an error of 2mm over the distance of the cassette. The width of the chain is important.

you should both note, you've both made comments regarding chain width and how it correlates to the cassette, not the crankset which is where my question lies.

i suppose a more accurate question would be can you use a 9-speed chain on a 10-speed crankset.

[i12ride]

I'm just going to assume the chainrings for 10 spd are as much narrower as the cogs on the 10 spd cassette are. It's all about cog spacing and compatibility to me. It might not become an issue until you get the chain torqued up in a bind while climbing, you may have ghost shifting issues when the chainline isn't straight or it may not matter but I will only mix match things to make something work I have on hand thru trial and error. If buying parts then I won't do that. I just built a bike where the hg93 XT chain worked great on one bike but when I moved everything over to the new bike I had chain issues when in bind climbing. All XT 9 spd stuff. I had a KMC 7/8 spd chain laying around new that I decided to try with a SRM 9spd powerlink. It worked fine without issue...right up until the freshy fresh PC991 chain for 9spd stuff showed up in the mail. I thought the 7/8 spd chain was great and smooth and trouble free until I put the 991 on there and it made another huge difference in smooth shifting and smoother going thru der pulleys when spinning backwards. It's a crapshoot mixing and matching stuff from what I have experienced. Sometimes you win and sometimes not. I tend to save those chances for situations where you just need something to get by for a minute or something that'll get ya back to the car without walking.

[DELTUFFO]

Originally Posted by cderalow

i suppose a more accurate question would be can you use a 9-speed chain on a 10-speed crankset.

Yup.