The use of 1x chainring in the front has become relevant not only in MTB and Gravel, but even among road bikers and triathletes there are periodically transmissions with a 1x chainring. The appearance of cassettes with a large range made it possible to get rid of the front left gear shifter, at first on top model bikes, and then on more budget models.

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The use of the 1-speed transmission in front became possible, in part, due to the design of a special chainring. The main task of the chainring with Narrow Wide teeth is to hold the chain securely under any loads and oscillations due to closer contact between the chainring’s teeth and the chain links.
1x chainrings are for Direct Mount or for Spider Mount (BCD – bolt circle diameter).

Do I need a 1x transmission on the Road bike? Will the 1x transmission become as popular on Gravel bikes as it is on MTB? For whom is 1x more suitable and for whom 2x? What is the advantage of one transmission over another? Let’s try to break it down for you.

First question, who even needs just 1 speed chainring in the front?
We would like to highlight 5 main points.

1. Where and how you ride a bike.

Classic cross-country: descent and immediate ascent, fast turns, and dynamic acceleration. With such a frequent need to switch, you will have to devote a lot of time and concentration on the left gear shifter. Remember the position of the chain on the big or small chainring in front, compare and synchronize with rear derailleur position. In addition, you have to pay attention to the brakes, and to locking the suspension. In such conditions, 1x chainring will have an advantage.

2. Cassette.
Having a large range of gears behind means that there will be a relatively large difference between the chainrings. This has a pluses and minuses. A plus is you only need to switch once to significantly change the gear ratio, and the downside is that it is more difficult to choose the right gear. This places certain demands on the rider to be able to produce a peak of power in a wider range.

3. More space on the steering wheel.
Many MTB bikes are now equipped with a dropper, fork, and shock absorber lock, and the presence of another lever complicates their installation. No lever means there is more space and less weight.

4. And by the way, more about the weight.
If you consider the difference in the weight of the cassettes, the lack of a front derailleur and a front left gear shifter and shift cable and housing, as well as one or two chainrings, can save you 300-500 grams.

5. Chain Suck
A very unpleasant situation when the chain gets stuck on the large chain ring while
down shifting, doesn’t release at the bottom of the rotation and hence gets
“sucked” up between the chain rings and the chain stay. Of course, on the 1x Narrow Wide Chainring there is still a risk that the chain will tighten, but this risk is minimal.

1x chainring for Gravel bike:
More than half of Gravel bikes are equipped with 1x transmission from the factory.
A perfectly matched transmission on a gravel is not the most important role, unless you are trying to keep up in a group of road bikers and for you the difference in pedaling frequency at 5% is not critical.

However, Gravel is rarely used on steep slopes or on highways, it is a very versatile bike, so you should choose the gear ratio in the right range with a chainring of the right size.
For a typical gravel with 28 wheels and 40 mm tires, 36-40T is well suited
If you are in good physical shape, you can set a 42-46T chainrings.

Of course, such a system has disadvantages.
In addition to the large step between gears, such 1x transmissions have a smaller range of gear ratios.
For example, in a typical 1x transmission, the range will be less than 400%. But if you have 2 chainrings in front, the range increases to 480%.
But these disadvantages are more than offset by its advantages. Especially if the range of 480% is not required: no levers, one chainring and cable chain gives a very minimal probability of having Chain Suck.

1x transmission for Road bikes:
Very often 1x chainrings are used by triathletes. But only when the set height is not significant and you can cover the entire required range of transmission. And the 1x chainring is more aerodynamic due to the lack of a switch and a second chainring. A big plus is the wide line of AERO chainrings, which help to improve aerodynamic characteristics.

Let’s summarize.
1x transmission is a popular trend in both MTB bikes and Gravels. Thanks to the large cassette, you can cover the entire required range and get rid of “extra” switches, chainrings, and levers.
On Road bikes it is rare due to the need to cover a large range of gear ratios and keep as little difference between the chainrings of the cassette.