I'm buying a mountain bike from a company that lets you choose the drivetrain. I am having trouble deciding whether to go for a 1 x 10 speed Deore option (11-42) or a 1 x 12 speed SLX (recently released) (10-51) or GX Eagle Sram (10-50) option. My budget could stretch to the more expensive 12 speed options. But is it worth it? Can't seem to find a definitive answer and cut through all the marketing. What are the pros and and cons of 10 speed vs 12 speed drivetrain on mountain bike?

Some obvious benefits of the 12 speed:

  • Range

Negatives (correct me if I'm wrong):

  • Less distance between shifts?
  • Alignment very important for smooth shifting.
  • More expensive.
  • Quicker to wear out?

Previous drivetrains I have tried:

  • Traditional mtb 9 speed with triple front ring
  • 1 x 10 and 44 tooth front chainring on my commuter bike
  • 2 x ? on my road bike
  • GX 11 speed when I demoed the mtb I'm looking at
  • singlespeed huret flip flop
  • 8 speed XTR.
  • fixed gear
  • mountain bike fixed gear
  • 7 speed SIS
  • 7 speed gripshit
  • Sturmey Archer 3 speed Chopper
  • Is this your first mountain bike? If not what drivetrain configurations have you tried and what did you like best?
    – David D
    Commented Jul 10, 2019 at 20:10
  • @DavidD Added some details above. Commented Jul 10, 2019 at 20:59

3 Answers 3


It comes down to what you would enjoy more - how you prefer to ride vs cost.

I can't find any durability tests I trust but from my reading the general impression I get is that 10 speeds is no more or less durable than 12.

You have ridden many different drivetrains so you have built up experience that should guide your preference. 2 extra speeds in the shifting range is nice, is it nice enough to justify the cost? Only you can make that call.

  • Why can't it just be that 12 speed is better? Surely more range is better? Commented Jul 12, 2019 at 11:47
  • @AndrewWelch Durability of the 10 speed system, in particular of chain, might be better than those of narrower 12-speed chain. Maintenance costs when it is time to replace worn components and availability of emergency replacements in world's remote locations are in favor of 10 or even 9 speed systems. But prices of 12-speed groupsets fall steadily, so it might not be a real issue. Compatibility with already pre-owned drivetrain components may also be a deciding factor; but if you are buying a completely new bike then I'd say go for 12-speed. Commented Jul 12, 2019 at 11:56

my favorite OneBy drivetrain is micro shift's adventx.

it has a wide raito for a 10spd and is on par with shift quality of Sram's GX 12spd (it comes close to the same gear ratio to)

also clutches are important and this one is not as effective as Shimanos shadow, but better than Sram's paw and ratchet clutch.

also shifter cassette and derailleur only cost $160 and you can get them cheaper if you do some digging.

i have a stock pile of micro shift's 10spd parts for mountain and road

i use the 11-42 for my xc bike and 11-48 on my santa cruz megatower.


Is the 10 speed option a single ring setup (1x10)? If so, you are correct: you'll get a lot less range with the 10 speed option. Quite a bit less as the 12 speed stuff is meant to provide a huge range with a single cassette. The Sram 12 speed cassettes have a giant lower end, 50. Paired with a 30 or 32 tooth chainring in the front you should be able to climb pretty much anything within your technical abilities.

If the 10 speed setup has multiple rings, then you need to ask yourself if that is what you want. You might get a bit more range out of a 2x10 or 3x10, but the advantages of a single ring setup are huge: less dropped chains, no front derailleur, simpler operation and less weight. I've been riding 1x for years now and will never go back, the drivetrains are just too good.

  • Deore M6000 has 2x0 and 3x10 options. I doubt a manufacturer would offer a 1x10 Deore option with a different single ring crank. Commented Jul 10, 2019 at 20:35
  • SRAM 1x12 cassettes (known as "eagle") have a 50T largest cog. Shimano's new 1x12 cassettes have a 51T largest cog.
    – Paul H
    Commented Jul 10, 2019 at 20:47
  • @Fingel I've added some details to my post. Commented Jul 10, 2019 at 20:59
  • @Paul H, Bear in mind that some SRAM cassette have a 10T:50T, so have 500% range. Shimano smallest sprocket is 11T:51T which gives 463% range.
    – Lou O.
    Commented Jul 11, 2019 at 9:12
  • 1
    @LouO. that's incorrect. Shimano has moved away from the hyper glide driver for their 12-speed groups in favor of MicroSpline, which allows them to have a 10T smallest cog: bike.shimano.com/en-US/product/component/slx-m7100/…
    – Paul H
    Commented Jul 11, 2019 at 13:48

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