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good day maam/sir, i would like to ask for some ideas if i can use the new Deore XT Crankset 1x12 (36t) to my 9 Speedchain + 9 speed cassette? If not, how about 10 speed chains + 11-42 10 speed Cassette?

Thank you in advance.

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  • Hi, welcome to bicycles. Can you clarify your second question? In this case you're still looking at it with the new crankset, correct? – DavidW Mar 17 at 18:08
  • Thank you sir. Id like to know the compatibility(will it work, no chain fall off) of 1x12 Crankset (m8100 - 36t) to my current groupset which is 9 speed shifter, rd, chain and 12-36 Cassette. If not, then how about i upgrade my groupset to 10 speed shifter,rd, chain and cassette 11-42. thank you. – TheGoodSamaritan Mar 23 at 2:49
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Good day, i just want to update everyone that I already used the 1x12 XT Crankset with my 9speed cassette/ 9 speed chain. i haven't had any problems with it or chain drop for 1 month of using now. thank you

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Seems to be two options here.

  1. going from ?x9 to a 1x9 using a 12 speed single chainring (m8100 groupset?)

  2. going from ?x9 to ?x10 by replacing the cassette and chain but not the front?

The first option should work okay - you're removing all the chainring/s and fitting a replacement crankset. This forgoes all the small chainrings, so the low-low gears will be gone completely.
Your front derailleur might go, or you may need to keep it as a a chain-keeper. The left-hand shifter is redundant.

Your biggest problem there is having the right bottom bracket to fit the new cranks, which appear to be Hollowtech II and require something like a Shimano BB52. If your frame takes something else, then some mix and match will be required.


Option 2 would replace your existing 9 speed cassette with a 10 speed. This should simply slide onto the existing hub.

However you'll need a new rear derailleur and shifter with an additional position.

The derailleur would have to be 10 speed, like a M786. Note BOTH the SGS (long cage) and GS (medium cage) are only rated for a 36 tooth low gear, so a 42 tooth is pushing it a bit too far.

The new 10speed chain should run well-enough on the existing chainrings, assuming they're not worn.


Your other option is to look at a GRX 11 speed, which can go to 42 tooth.

Also consider the cost of all these parts, and whether a new bike works out cheaper.

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  • thank you for your prompt reply. For Option 1: im using 1x alivio with 36t now, actually im using 9speed chain with 9 speed cassette 12-36(alivio). i just want to replace it with m8100 xt 1x12 crankset 36t because the deal is like off with 30-40%. im using a hallowtech 2 bb also. I just want to know the compatibility. thanks for your reply. i guess thats a good deal. – TheGoodSamaritan Mar 16 at 3:04
  • Option 2: If ever i was able to have the new 1x12 xt crankset, so upgrading my gear to 10 speed would have no problem. To be honest, i just wanted to have atleast 42 with my highest cogs because i dont really need higher than those in my place, i wish shimano should sell higher end 10 speeds, but i think the deore m4100 upgrade kit would be good also since i have no problem with my stock alivio groupset. – TheGoodSamaritan Mar 16 at 3:14
  • Option 3: Yes, im also checking the cost of new bike to the upgrade, its just this bike was given to me by my friend so this has sentimental value and this is my first bike, then if i ever upgrade later on to 10 speed, i think it would be good also since the cost and upgrade will be progressive. Btw, im using Giant Talon 2 2018 model, all stock except for the Fork w/c i upgraded to Manitou Machete, and i change my 2x Deore crankset to 1x alivio(temporary and with this im checking this 1x12 xt crankset) so i can utilized the internal cabling route for my dropper seat post.Thank you very much – TheGoodSamaritan Mar 16 at 3:20
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Typically one can fit a front drive designed for one speed with the rear drive designed for another speed if the difference is +/- one speed. It's best to go with the chain that's correct for the rear drive, 9 speed chain in this case. However, i question the compatibility of a nine speed chain with the 12 speed crankset, though i cannot say what symptoms will result from such use other than less than ideal chain retention possibly. The internal spacing of chains doesn't change with increasing speed rating, but the overall width of a chain decreases as you move up to more speeds. This may infer that a 9 speed chain should run fine on a 1x 12 speed chainwheel, but i can find no anecdotal information regarding this. Using an 11 or 12 speed chain on a 9 speed cassette will present problems with smooth shifting and the big danger would be risk of severe chain jam should the thinner profile chain of 11 or 12 speeds get stuck between cogs of a 9 speed cassette which are spaced wider than an 11 or 12 speed cassette's cogs. These types of jams can be severe, going in under power jams the chain quite tight which then has implications for the involvement of the derailleur. It is not something one wants to encounter mid-ride and have to deal with at the trail side as there will almost certainly be damage to the chain at least.

If i had to make this situation work, i would opt for a 10 speed chain, preserving good rear drive compatibility. Hopefully you have a front chain guide in place to aid in chain retention. There are few if any models of 9 speed derailleurs with a clutch system, which, when combined with a narrow-wide chainring, are the two most important aspects of a 1x system to keep the chain on the drivetrain.

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  • thank you sir, ill buy a 10 speed chain also. and i will update everyone here when the crankset arrive. – TheGoodSamaritan Mar 23 at 2:50

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