How do you choose 1x or 2x for your Gravel Bike?
Which one is better?
We get asked this a lot in the shop and we spend hours discussing it.
1x (commonly called "one-by", as in 1 by 11 or 1 by 12) and 2x (likewise called "2-by") are the drivetrain specs on almost all the gravel bikes out there, and it's wise to move this choice between the two high on your list of criteria when choosing a bike to purchase or drivetrain to upgrade to.
1x Drivetrains
1x started around 2014 or so as a premium feature on high end mountain bikes - no front derailleur, and a super-fast shifting from a high gear to your lowest gears in a pinch - a super common situation when riding mountain bikes. It started coming down in price and nowadays can be found on mountain bikes down to the lowest entry-level hardtails. Nothing comes with 2x or 3x anymore. Kids and beginners appreciate the simplicity, we used to spend a lot of our resources in retail explaining how and when to shift the front derailleur. A lot of people found it too hard and I'd venture a guess many people never figured it out into adulthood. When applied to a gravel bike, it saves weight, less to go wrong, and in certain riding conditions is definitely advantageous.
But... the Big But. Working in a workshop we get to see the long term results and rider complaints, and rider issues that are not that uncommon. Riders who do a lot of flat & rolling rides, riders who do a lot of kilometers and ride their hardtail or gravel bike with a 1x drivetrain wear out cassettes and chainrings super quick. Something that can and should last years in many cases, can last only a couple months until it starts skipping and popping under power. We've seen it many times. For commuters it almost always gets a NO from me.
Why? The gaps between gears are bigger, so when rolling along a fairly consistent gradient, there's only one gear that seems to be close to the ideal cadence. The one up is too low, and the one down is too high, and that ideal gear is almost always one of the small ones - 14 or 15tooth. So, it wears super quick. When it wears, the chain starts to pop and slip when under power. The front chainring, since it's the ONLY chainring, also does the same thing - it's usually a smaller tooth count than the big ring on a double setup - and the chain stretches prematurely as well. It gets expensive very quickly and 90% of the time baffling to the rider and shop employees until they figure it out. It's cause for a decent amount of frustration, and when I can avoid it I do.
Best to keep 1x on the gravel bikes that are ridden more offroad, more mountain bike-style riding where there's a lot of up & down, a lot of shifting & the use is spread across a wider range of gears.
Side Note: Sram has recently come out with 1x13 and they claim that the gearing increments are tight on the smaller gears (where this is a bigger issue) and the gaps grow as the cassette gets bigger - which totally makes sense. I have yet to ride a 1x13 gear bike, and will update this when I do. It still only has a total of 13 gears, as opposed to a 2x12 with 24 total usable gears, yet I remain optimistic.
2x Drivetrains
Nothing beats a 2x drive for most flat to rolling gravel rides - which happens to describe most gravel riders (and rides) we cater to here in Melbourne. The gears are numerous, small increments between gears (so you end up using more of them), and you still have a great range from the lowest of the low for steep climbs - to the high gears for descending your favorite paved descents out of the hills. Maintenance costs are kept in check with regular chain replacements, cassettes and chainrings wear in at normal intervals, nothing out of the ordinary. Riders seem to be happy and less hassle working through difficult learning experiences with replacement parts and shorter replacement cycles.
The selection of bikes from all the gravel bike manufacturers seems to be quite varied. Some brands definitely favor one or the other, and some try to cater to both. It probably has a lot to do with where the brand's roots are, and brands with a lot of mountainous terrain in their backyards probably favor 1x - it makes sense for them. A lot of the bigger companies with global reach have more inputs from afield, and they seem to offer a more balanced offering of 1x and 2x-equipped bikes.
At times I have found it difficult to find the model I want in a double and have taken a 1x model instead. I don't do the high miles that others do, so the maintenance was not an issue, but I really found the inability to find the "perfect gear" frustrating and noticeable when looking for just a little gear up or down. When the wind picks up a bit and you need to gear down slightly... or when you tuck back into the back of a group and can take it up a small gear higher... Ah! too high, Ah! too low, and back to that "good enough" gear, but no Goldilocks gear. Advantage: 2x
When doing the offroad, mountain bike-style riding on the gravel bike, the front derailleur on a 2x drive can admittedly be a hassle - trying to coordinate downshifts on the front along with the upshifts on the cassette in the rear takes coordination and foresight, not always possible when riding down a bumpy trail at speed. Advantage: 1x
In Conclusion
Both 1x and 2x drivetrain styles, whether from Shimano or Sram, electronic or mechanical, are functional across a wide range of riding and both can be ridden across the full spectrum of gravel riding. But 2x shines on competitive-style & adventure gravel rides where the terrain is mostly rolling to flat, and 1x is unmatched when doing technical singletrack where there is more rapid changes in elevation and rapid changes in gearing are necessary.
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Below, I've posted our most up-to-date Gravel Experience Chart and although not every bike and rider fits neatly into a set category, it can be used as a guide to steer buying and setup decisions to within a decent margin of error for any rider. Of course it does not cover every detail, but generalizes the offerings and the styles of riding on offer today.
