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I didn't ride bikes for quite some time and decided to start again this year. I'm currently looking for a MTB that will be kind of universal, I'm pretty much set on everything and picked few models, but now I'm faced with one final choice: either a model with 1x12 (Shimano Deore M6100) drivetrain or 2x10 (Shimano Deore M4120 and M618).

I'm going to use this bike on:

  • forest trails

  • gravel and dirt paths

  • partially paved roads to get to actual trail I'm going to ride on

  • lots of climbs and descents, not flat routes

I'm not going to use it to cycle in the city and (at least currently) I'm not even thinking about using it on more technical advanced trails. A friend told me that 1x11 or even 1x12 should be great for me, but when I was looking at the bike in the shop the dealer told me that for my use case 2x10 would be much better as it's more universal but not as great for highly technicals trails (that I don't know if I will even use).

Does it really make that much of a difference?

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  • I think you'll advance to tech trails faster than you expect and you'll prefer the single chainring up front.
    – Paul H
    Commented Aug 3, 2022 at 14:09
  • @PaulH but a modern 2×11 works very well on moderately technical trails. Whereas for the kind of extreme rock gardens where 2× gets into trouble, the bike in question probably doesn't have good enough suspension anyway. Commented Aug 3, 2022 at 19:30
  • @leftaroundabout Hmm. I don't see any info about the bike or suspension, so it's hard to comment on that. The OP is asking about 2×10 as well, which might be as good as modern 2×11 kit, but I don't have experience with it. Last time I use 2×10 on a MTB was 2014 - 2016, and I didn't find the front shifting to be terribly great under reasonable load (Shimano XT components)
    – Paul H
    Commented Aug 3, 2022 at 19:53
  • @PaulH of course the front shifting isn't great under load, reasonable or not. A front derailleur isn't supposed to be shifted under load (possible exception: electric shifters). However most of the shifting is still done with the rear mech, which as you know can handle single-gear shifts even under high load – but even there sudden multi-gear shifts should always be carried out with momentarily released torque to avoid gear crunch. And then a 2× actually gives you a bigger shift for the buck (=release time), because you can simultaneously shift both derailleurs during a single torque lapse. Commented Aug 3, 2022 at 21:24
  • ...To be precise, the optimal technique is actually to first shift the rear mech still under load, then wait for ¼ rear-wheel rotation (depends of course on speed how long this is), then drop the torque whilst shifting the front mech, then pedal ½ crank at idle-torque, before finally giving full power in the new gear. Commented Aug 3, 2022 at 21:30

4 Answers 4

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For your use case of 'universal' (many would call this oldschool XC) riding you want the widest gear range possible to allow pedalling up both steep climbs, but also on non technical downhills. At the same time, you want to preserve as small as possible gaps between gears to allow you to maintain a comfortable cadence.

For this use case a 2x10 setup is still clearly the best choice as it offers the same range as the most modern 1x setups with smaller jumps between gears.

Unfortunately the bike industry doesn't like to acknowledge this type of riding exists and is heavily pushing towards making 1x the only option for MTB. This is a shame, because a 2x12 MTB groupset would be extremely versatile and could be great for gravel bikes and even entry level road bikes.

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  • 2x10 offers a slightly wider gear range. You can have a 11–42t cassette and a 36/26 crankset. That’s 529% gear range with ~17% jumps between gears. With 1x12 you are limited to an 10–52t cassette with 510% gear range with 18% jumps between gears. 2x11 speed would actually be perfect, also because maintenance is cheaper.
    – Michael
    Commented Aug 1, 2022 at 11:59
  • @Michael on MTBs, 2x11 is not an interesting combination to my opinion. Pretty much limited to 11/42 cassettes, so no range benefit compared the setups proposed here. And if you go for a modern 2x12, you'll have a 640% range.
    – Rеnаud
    Commented Aug 1, 2022 at 12:29
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Assuming that the recommended cassettes/chainrings are proposed, ranges will be equivalent.

  • 36/26 chainrings, 11/42 cassette for the 2x10: 523%
  • 10/51 for the 1x12: 510% (for 1x, the range of doesn't depend on the chainrings). Note that sometimes, 11/51 are offered with the M6100, so in that case the range advantage goes to the 2x.

There are also a lot of "redundant speeds" on a 2x10 setup, the number of actual different ratio is closer to 14 than 20.

But the range is just a ratio between the highest and lowest combination. It doesn't give any absolute indication.

So the answer will depend on the chainring: if the 1x12 has a 32T chainring, the range will be meant for lower speeds/steeper climbs. If the chainring has a 36T chainring, the two bikes will be really equivalents — replacing the chainring is usually simple, that being said.

Personally, just based on this difference, I would go for the 1x12. Simpler to operate, and also uses a slightly higher product range than the 2x10 and it's a more up to date design. The 1x12 also has a very small advantage if you want to fit larger tires.

Finding spares or upgrades will be easier: the 1x12 has just been upgraded on the whole Shimano mid- and upper- range (Deore M6100/SLX/XT), and you can mix components: you can have a XT shifter, SLX cassette and Deore derailleur. The 2x10 is a mid-range product, and the availability/offer of spares is already declining. From my research, finding spare cassettes for the M4120 is currently very complicated (hint: 2 of the 4 bikes at home use a 11/42 10-sp cassette), availability in Europe for this cassette is close to zero. What will happen in the future is only speculation, but seeing how the bike industry has reacted to the shortages, it was clear that the priority has been given to higher range products. So buying this specific configuration now is a bit of a bet:

  • supply issues are solved, and in that case finding cassette won't be complicated. But the offer will probably limited to the steel ones — not an issue per se.
  • supply issues are not solved, and in that case, you'll have the choice of running your bike with out of spec components or replace more just than the cassette because of a lack of spares (there's some nuance to that, but it's better to address it in a separate question).

[EDIT] I remembered that the RD-M4120 is actually a 10 AND 11 speed rear derailleur. Given 11/42 11-speed cassettes are still widespread (still the default for Shimano 1x gravel drivetrains and SRAM Apex). The argument of not finding spares is actually not valid for this rear derailleur. To use a 11 speed cassette, only the shifter (and the chain) needs be replaced, the rest can be kept as it is.

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  • I can't see 2x10 being any trouble given that I can easily find parts for both my 2017 3x9 drivetrains (MTB and tourer) and my 2010 3x8 hybrid.
    – Chris H
    Commented Aug 1, 2022 at 12:50
  • Thanks for in depth explanation. I see 1x12 is offered with 10-51T cassette and 34T chainring so it's kinda in between. If replacement is simple then I can just replace it with 36T if/when needed. Meanwhile 2x4 is 11-42T cassette and 36/22T chainring. Commented Aug 1, 2022 at 12:52
  • @ChrisH There's little difference between older 3x9 and current 3x9, there's not so much evolution in this market. 10-speed 11/42 cassettes are much more of a niche (Deore M6000, M4120). The light version of the cassette are not available anymore, only the heavy ones remain (it's not critical, but I were to invest in a bike now, I'd rather take a good evolutionary path). I would not have written that for a 10-speed trekking, that being said.
    – Rеnаud
    Commented Aug 1, 2022 at 13:06
  • @ChrisH I just checked on the big online shops (Bikester, Alltricks, Probikeshop) + some small ones. There are currently no 11/42 10-sp cassettes available. FYI: it was also the case one month ago when I asked the question about replacing the sprockets individually - I asked this question specifically because of the lack of 11/42 10-speed cassettes, and because I saw that I could buy some sprockets separately (my fun bike uses this cassette, as well as my wife's trekking ebike).
    – Rеnаud
    Commented Aug 1, 2022 at 13:40
  • 1
    +1 for mentioning the redundant speeds Doesn't get enough mention in my view particularly since cross chaining causes significant avoidable wear
    – Hursey
    Commented Aug 1, 2022 at 22:05
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Not covered and answers already is durability and cost. A 12 speed drive train costs a lot more than a 10 speed, so when if comes time to replace worn (and broken) components, a 10 speed setup will cost you a lot less. However, 1x and and 11 and 12 speeds are superseding 10 speed. I may not be long before you cannot get easily quality 10 speed gear (similar to 26" tire these days - you can get them, but the range is limited and often need special order). Special order is OK for replacing parts that wear, but can be a pain with breakages.

The main reason the manufactures are in love with 12 speed is it frees the area around the bottom bracket of full suspension bikes. This is a highly stressed and crowded location on the frame, and removing the front derailleur allows a lot more freedom for designers. It also reduces assembly time but removing a complete set of shifters and derailleur, a big cost saving. If the frame can accept a front derailleur, you are not getting most of the benefit going to 1x gives manufacturers.

To me the decision is not about the technical aspects, as for your use case both drive trains will perform equally well. Its about what is more important to you - cost (immediate and ongoing) or sex appeal.

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Personally, i ride a 3*10 setup on my MTB/Tourer. I think that this is a very good universal setup. Mine is set up so that most of the time i'm riding on the middle chainring, with a cadence of 85 - 90, which i am most comfortable with. The large and small chainrings are only needed for extreme situations, i.e. steep up- or downhill.

A high(ish) cadence is what you should aim for. It allows you to ride for a long time without too much effort. And to maintain your preferred cadence, you will want a fine spaced setup.

So i'd definitely vote for the 210, or a 310 setup for what you describe as your needs.

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    In that case maybe even 3x9. 10 speed systems had a shorter market life and are declining (as mentioned elsewhere), whereas 9 speed are still alive and well as they occupy the entire lower-level niche. The components are still available and are really cheap (sometimes 1/4 price of 11-12 speed systems); even the higher-end lines of replaceable components (chains, sprockets) are easily obtainable.
    – Zeus
    Commented Aug 2, 2022 at 0:46
  • @Zeus even nicer, with 3x9 (which I have on 2 bikes) 8-speed parts will get you home and they're very common and even cheaper. 9 speed chains also seem stronger.
    – Chris H
    Commented Aug 2, 2022 at 12:54

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