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I don't know much about bikes.

I bought a "Kona Dr. Dew" 10 years ago, it has a 3x9 set of gears. The front rings large and small have 50 and 30 sprockets, and so I guess that's (9 * 50 / 30 =) at least 15 different speeds.

I like that fine:

  • The range is wide enough:
    • I can use the top gear only on a downhill
    • I use the bottom gear only on very rare steep slopes of like 20% or more (e.g., in a city, climbing the ramp out of an underground parking garage)
  • The difference between adjacent gears is small

I see this year's version of the same model has a 1x12 ("Shimano Deore 10-51t 12spd").

They advertise ...

A 12-speed groupset keeps shifting ultra-smooth and geared for any big hill the city may have.

... so I guess it's meant to be comparable to the 3x9 I have now.

Can you bring me up-to-date?

  • Why only one ring at the front these days -- why didn't they used to be like that?
  • How is the user experience the same, or different?
  • How does it affect reliability and maintenance?
  • Are models with 2 or 3 rings at the front still mainstream, on a new bike in that kind of price-range, or is 1 at the front the new normal?
  • Are the chains quite specialised, e.g. do you need a different type of chain for a 12-speed than for an 11-speed? How many types are there?

This is for an "urban" or "hybrid" bike, so "weight" is presumably not an especially important consideration -- or not for me at any rate, e.g. I carry a heavy bike lock on the bike.

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  • For my road bike I prefer 3x vs 1x setups. This is because you can set a range with the front, then "fine tune" with the rear. Plus, if you need to make a major gear change the 3x is faster in getting you to the range you want. Aug 29 at 12:35
  • I like my 3x just fine. I was wondering if I'll be able to get it again, if I buy a new bike in future; or whether 1x is as good.
    – ChrisW
    Aug 29 at 13:55
  • I use it like you said: on the biggest of the three, with the rear usually on 5 through 7 (9 is too high for me except downhill); if 5 isn't low enough (on a hill) then I drop to the second of the front rings; the granny ring is very rare i.e. only for unusually steep hills. And I drop to the second ring when coming to a full stop, restart from there and make a "big jump" from the 2nd ring to the big ring on getting up to speed. A big drop down is sometimes helpful when a hill starts suddenly, but I often combine a big drop down (on the front) with a small step up on the back.
    – ChrisW
    Aug 29 at 14:51
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1× setups have become the norm on mountain bikes. They're very common on gravel bikes. I don't think they're common on hybrids, at least not yet, but I wouldn't be surprised if they are in a few years. There have been a few 1× road bikes, but they're rare beasts. 2× setups are still the norm on road bikes.

The main benefit to 1× is simplicity. You don't need to think about your shifting pattern at all. This is a benefit, especially to newer riders, who may not understand how to use front and rear shifting effectively. It's also a benefit in the sense that it removes things that could break.

However, as the number of gears goes up, chains need to be narrower, which makes them a little more prone to wear. And they have more stringent setup requirements (back in the old days, we could reuse normal rivets—these days we need special one-shot rivets or master links).

It's helpful to imagine what the ideal gearing would be: a low gear that lets you climb the steepest hill you'll find, a high gear that lets you ride fast when you've got a tailwind, and consistently spaced gears in between that are close enough that you never feel like you're "between gears," but not so close that gears feel redundant. And it should be easy to use and efficient.

Every gearing system compromises some aspect of this. 3× (and to a lesser extent 2×) systems are harder to use. They also sacrifice a little efficiency when cross-chained (and there's a tiny bit of inefficiency with any crossover gearing system due to redundant ratios). But they can give a wide gearing range and close steps between gears. A 1× system is either going to compromise on range or on close steps; on mountain and gravel bikes, the steps are generally wider to maintain the range. Road bikes have the complexity of crossover shifting, but have close spacing so that you can always find the right gear, and pretty good range.

Over the years, we've seen more and more gears added to the rear cluster. This is partly a marketing schtick, and partly an effort to achieve this ideal shifting. Once we reached a critical mass with the number of sprockets in back, it became feasible to start eliminating chainrings in front.

Hybrids are more likely to be ridden by inexperienced riders, who perhaps are more likely to be impressed by a bike with (nominally) 21 or 24 speeds than one with 11 or 12—even if the 11-speed would suit their needs better. Also, hybrids tend to be less expensive, and use less expensive parts, but the 11/12/13-speed drivetrains are only found in more expensive component groups.

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    The original main driver to 1x was soft tail mountain bikes. Removing the front mech made room in an overcrowded and high stress area for the frame builders. Manufacturers loved the lower cost (fewer parts, less assembly time etc) but failed to pass it on when marketing took over as 1x was a visibly obvious point of difference.
    – mattnz
    Aug 28 at 21:53
  • @ChrisW Aside from the obvious powertrain changes, it looks like the current model you mentioned uses a 142mm wide rear wheel hub (your older bike likely used 135mm) and 12mm thru axles on both front and back vs. likely QR (quick release) axles on the older bike. The 135mm rear spacing may cause some issues in trying to move to an 11sp or 12sp rear cassette.
    – Armand
    Aug 28 at 23:16
  • @Armand Rear spacing does not dictate possible speed counts.
    – MaplePanda
    Aug 29 at 0:57
  • @MaplePanda I was thinking of wheel/cassette issues like interference with spokes or hubs too short for the cassette; my perspective is looking at older 26" wheels, so as you note a problem is less likely.
    – Armand
    Aug 29 at 2:23
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    Evenly-spaced gears within target high/low range is one definition of “ideal gearing”, but not the only one. An ideal gearing also might allow directly shifting into any gear (“random access” into the gear range, using computer terms). 1x enforces sequential access, but 2x and 3x offer two-dimensional gear-selection in a way that comes close to random access.
    – RLH
    Aug 29 at 14:51
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Why only one ring at the front these days -- why didn't they used to be like that?

I suspect the main reason for this is the availability of narrow-wide chainrings, the invention of derailleur with a clutch, and the increase of sprocket counts in the rear.

Previously, there was no way you could achieve enough range of gears with only one chainring because to achieve reasonable steps between gears, you'd have maybe some 11-34 tooth cassette that only has little over 3x range. Also you'd need some guide to prevent the chain from dropping. If the guide is perfectly successful in its job (never rubs on the chain, prevents 100% of chain drops) then a static guide is enough but even some small percentage of chain drops not prevented means you have to have some mechanism to move the guide without getting your fingers dirty in chain oil, and hey presto, the guide became a front derailleur.

Also complicating the fact is that 11-tooth sprockets have horribly short wear life and are massively inefficient. The same is true but to a much smaller extent on 13-tooth sprockets. So to have an acceptable wear life and efficiency on your flatland gear, it means your flatland gear should be the 15-tooth sprocket at a minimum (or perhaps even a 17-tooth sprocket). If the big sprocket is 34-tooth, the lowest gear is only 2.27x easier than the flatland gear. It may be a limiting factor should you encounter a very steep hill.

Today, narrow-wide chainrings and clutch derailleurs are available. They together reduce the risk of dropping the chain from the chainring to a very small value even if you don't have a chain guide.

Also with 10-sprocket (or more) cassettes, it became reasonable to have something like 11-42 tooth cassette. This has 3.82x gear range that ought to be enough, and the jumps with gears are suitable so you won't find that you are missing a needed gear in the middle.

There are still three advantage of multiple chainring setups for users of trigger shifters. Those shifters allow quick downshifting over multiple gears but don't allow quick upshifting over multiple gears. So if encountering a steep hill, you can quickly find the gear needed for that hill. However, after the hill it's a different matter. If your flatland gear is 15-tooth sprocket and you used the lowest gear for the hill, it usually means with a 12-speed system that you need to click 9 times the trigger to find your flatland gear. With a multiple chainring setup, fewer rear sprockets and front derailleur, you find the flatland gear faster.

Also theoretically it's possible to damage your chainring by accidental contact with a rock. On a multi chainring setup, you might find the smallest chainring still works, and if it doesn't due to the rock-damaged big ring obstructing it, a very quick bend with an adjustable wrench in your emergency toolkit bends the obstruction into the opposite direction. You don't even need to fully repair the damaged ring on roadside, only a very quick bend will clear the obstruction. With only one chainring damaged by a rock, your only option is to try to repair it fully.

Furthermore, with a multiple chainring setup, and small sprocket count, it slightly reduces a crooked chainline if used properly. This means the extreme gears can actually be quite efficient. However, on a single chainring setup, the extreme gears have a crooked chainline that reduces their efficiency. However, of course this requires too some knowledge by the rider of the bike that a good chainline should be maintained on a multiple chainring bike. Actually with a multiple chainring system, if cross chaining, the chainline can be even worse than on a 1x system.

Today the 1x systems are prevalent on hybrid, mountain and gravel bikes but not yet on road bikes. The main reason for that is probably that on a road bike you can't realistically have smaller than 50-tooth flatland ring (otherwise the rear sprocket for your flatland gear would have terrible wear life and efficiency), so a 1x-system would need huge big sprockets in the cassette to have low enough gears, increasing weight. It probably adds less weight if the low gears are implemented by a second small chainring. Also when riding on the road, you can usually anticipate your near future gear needs a long time in advance and have time to shift to the proper range (selected by the front derailleur) when riding on flatland. For mountain bikers, it's harder to anticipate gear range needs so much in advance. It makes more sense to have only one shifting system, one range, that allow executing every shift even under load or with minimal interruption in load.

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    Thank you for answering. Apart from the problem of dropping the chain, are you saying that an 11-tooth small ring used to "have horribly short wear life and are massively inefficient", that 13 was bad too, and that 15 or 17 was better ... but that now, "it became reasonable to have something like 11-42 tooth cassette"? Why is it that small rings are possible now when they were "massively inefficient" before?
    – ChrisW
    Aug 29 at 10:18
  • Ah, yes, we have had 11-34 tooth cassettes for long. In those cassettes, 11- and 13-tooth gears were very rarely used. Only if you wanted to go fast in favorable wind or wanted to pedal downhill as opposed to coasting. Today we have 11-42 tooth cassettes where too the 11- and 13-tooth gears are very rarely used. What changed is the number of sprockets, which allowed to change the big ring from 34-tooth to 42-tooth while still maintaining reasonable spacings between gears.
    – juhist
    Aug 29 at 10:52
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    @ChrisW To get a low enough low gear on say a 11-34 cassette would require quite a small chainring, say 34 or 36t. You’d have to be in the 11 or 13t sprocket when riding on flat land with such a chainring. Now, we have big cassettes, so a 40t+ chainring is feasible, and the flat land cog moves to the 15/17t.
    – MaplePanda
    Aug 29 at 16:19
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    The reason that 1x has failed to capture any market share in the road segment, despite there being a bunch of hullabaloo around it a couple years back, is because while you may be able to match the same gearing range as a 2x or 3x system, the steps between each gear are still too great, and none of the available gear ratios allow you to ride in a comfortable, biomechanically efficient cadence. This is less of a problem in mtb, where you're never pedaling at a consistent cadence regardless, but on the road, where power output and cadence remain mostly constant, it becomes a huge deal. Aug 30 at 14:43
  • I disagree with road riding requiring a narrow cadence band. Humans are not diesel engines that need to maintain an optimal cadence by shifting. In fact, the cadence efficiency band in humans is extraordinarily wide, far wider than for example in diesel engines.
    – juhist
    Aug 30 at 15:29
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How does it affect reliability and maintenance?

A good 1x system requires a clutch rear derailleur, which requires additional maintenance over a regular derailleur. As usual, the frequence of the service depends on many factors, and I don't have enough experience with clutch derailleurs to give a feedback, but it seems to on the low side. It may be too simplistic to think that 1x systems have less failure points because they don't have front derailleurs: 1x are more sensitive to clutch failures/poor maintenance than 2x or 3x.

Are models with 2 or 3 rings at the front still mainstream, on a new bike in that kind of price-range, or is 1 at the front the new normal?

2- and 3-chainring cranksets are still commonly found on sub 1k€ bikes and on road bikes. On upper ranges, there are 2x systems on "road focused" gravel bikes, and 2x systems for MTBs are still being developped ...but it's becoming increasingly hard to even find frames that can accommodate front derailleurs.

Recent MTB 2x systems have around 600% of range, 1x have around 500%. 500% is already very good, so it's only on specific cases that a 2x provide an added value.

That being said, as you noticed, the upper versions of sub-1k€ bikes tend to have either 1x transmissions ...or 3x high-end 'trekking' transmissions.

Are the chains quite specialised, e.g. do you need a different type of chain for a 12-speed than for an 11-speed? How many types are there?

Chains are made for a given number of speed, but there are some nuances. On the Shimano side: 12-speed Shimano are recommended for Shimano cassettes (for Hyperglide+ which offers a smoother downshift requires specific chains), and Shimano has also introduced a new product range, focused on durability (LinkGlide), which requires specific chains.

This is for an "urban" or "hybrid" bike, so "weight" is presumably not an especially important consideration -- or not for me at any rate, e.g. I carry a heavy bike lock on the bike.

For this use case, if you want to have the same 'range' as your current bike, my advice would be to pay attention on the chainrings you can install.

If you have a 68mm BB shell width, it's the easiest, then you can install gravel components, and 40T or 42T chainrings are common.

If your bottom-bracket width is 73mm, you can only install MTB components. Recent MTB chairings tend to be small (max 36T, but dominantly 32T), so the change might not be beneficial: you may not use your 2 or 3 biggest sprockets for example, and the smallest ones won't be 'sufficient', especially with 27.5in wheels.

The salvation can come from trekking components or entry level MTB components, but then you'll remain with 3x systems. The only exception I'm aware of being the Acera 46/30 crankset.

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  • Clutch maintenance is a <5 minute job for Shimano and a non-issue for SRAM (who uses sealed, non-serviceable clutches).
    – MaplePanda
    Aug 29 at 22:09

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