Those who are about to buy a gravel bicycle (or even those ones who already own one) surely have many questions. We know it in TodoGravel because we have lived it. And one of those questions is what kind of transmission do I want for my gravel? 1x or 2x?
The preferences are very subjective and will depend on the taste of each user. Here at TodoGravel we don’t even agree.
To decide on one or the other, there are factors that we must consider. On the one hand, the physical condition of each one, that this is particularly important. On the other hand, the type of terrain where we are going to pedal.
Below, we detail in a simple way the key aspects in order to help you in choosing one transmission or another. As always, we encourage you to provide your comments or experiences.
1x transmissions, or also known as single chainring, are not exclusive to gravel cycling. Other disciplines such as road cycling, cyclocross or mountain biking have used this type of solution.
There are certain advantages over dual chainring transmissions. On the one hand, using it is much easier since we only focus on a rear gear shift located on one of its levers. Weight reduction is also achieved, although this is not a decisive factor in gravel cycling (although this is not entirely true). In addition, its maintenance in general is much less and simpler.
If we focus on weight and comparing similar groupsets, the difference may be around a few grams. Even the Apex 1 weighs approximately 2,719 grams with a 42 tooth chainring. Outperforms the Shimano 105 dual-drive group with 2,443 grams. Therefore, and it is a tip, a few grams above or below should not be the decisive factor in installing one transmission or another.
«Are 1x transmissions lighter than 2x? Not necessarily. The Apex 1 weighs approximately 2,719 grams with a 42 tooth chainring. Outperforms the Shimano 105 dual-transmission group (2,443 grams) »
As for the history of the single chainring, many of you will know it. Sram launched 11-speed transmissions from her route groupsets, which the gravel quickly acquired as their own. Today we have the Force 1, Rival 1, and Apex 1 groups. Later, Shimano with the introduction of the GRX specialized in off-road bikes, also offers us within the RX800 and RX600 levels single chainring solutions.
Types of 1x transmissions
Here at TodoGravel we are users of the 1x and 2x transmissions. We will focus on 1x for now.
At the Merida Silex we have assembled the Sram Apex 1 groupset with a development based on a single 44 tooth chainring with a large 11-42t cassette. In our opinion, it is a transmission that on technical forest tracks is adequate, but it falls a bit short if you are looking for speed on paved roads. But, for Vicente (owner of the Silex) it is enough.
In addition, Vicente has changed his perspective (since he came from road cycling with developments based on compact chainrings) that gravel cycling is more to enjoy than running. Or as someone said it; in gravel it does not matter how long it takes to get to the destination, but how the destination is reached.
The usual drives that we come across are 38 tooth (too small for us), 40 tooth and 42 tooth chainrings. As for the cassettes, an 11 / 36t or 11 / 42t is usually mounted. Smaller does not advise it for single chainring.
Until the appearance of the 1x, the first gravel bikes normally featured developments similar to road bikes. Double chainrings subcompact 50/34 teeth with small cassettes of 11-32t or 11-34t.
So, it was easy to advise gravel users to go for 1x solutions. As a general rule, gravel cycling runs on heterogeneous roads and steeper slopes. Hence, for some, a 2x asphalt type transmission may fall short or may not be the most suitable. But as we said before; It depends on several factors, such as the power of your legs.
Types of developments 2x
But with the appearance of smaller double chainrings made by many manufacturers (FSA, Praxis, Easton, etc.) and lately of Shimano GRX, everything has changed. A solution based on a subcompact with for example 46/30t chainrings and an 11-34t cassette is a good choice. The manufacturer Sram opts for a combination based on 46/33tt and a 10-33t cassette as the perfect choice for gravel cycling.
« Shimano GRX came to give a boost to 2x transmissions, as Sram dominates 1x transmissions»
Shimano offers us for its GRX a sub-compact solution of 48/31t, or 46/30t and combines them with an 11-34t cassette.
Jaime has a Praxis Alba 48/32t double chainring and an 11-34t cassette mounted on his Giant Revolt Advanced 2. He finds it almost ideal for gravel, although he will most likely trade the cassette for an 11-36t, so he doesn’t suffer too much on steep climbs. This is cheaper than changing the crankset.
Although in gravel cycling speed does not matter much, sometimes you have to enjoy it when the opportunity presents itself. For example, on long descents. This is when the 2x transmission is more enjoyable since you can achieve higher speeds than with a 1x transmission.
In the following image (taken from 99 Spokes) you can see on the horizontal bar chart the range gear of three bikes, two of them have double chainring (Revolt and Topstone) and another single chainring (Aspero). The ones that have double chainring have a wider gear range and the Revolt has a bigger one and can reach a higher speed.
Below the bar graph you can see the groupset that each bicycle mounts.
After many discussions these are our main conclusions in TodoGravel:
- If you come from road cycling, and your rides will be something like 50% asphalt and 50% less technical forest tracks, we recommend a double chainring transmission based on a 48/32t or 46/30t and an 11/34t cassette, maybe an 11/36t.
- If, on the other hand, speed is not your priority and simplicity is your preference, the 1x option with a 40t or 42t chainring and an 11/36t or 11/42t cassette is your best choice. It is a calmer gravel.
Finally, the best way to check all of the above is to test both transmissions yourself. To do this you should go to your bike shop or ask your friends to lend you their gravel bikes with 1x or 2x transmissions.
And if you cannot do the above, like most cyclists or potential cyclists, then it is to study the subject well and trust your instincts to decide which transmission is best for you. Good luck with it and we are here to advise you.