Choosing between a single chainring (1x) and a double chainring (2x) drivetrain for your gravel bike can feel overwhelming. However, by considering your riding style and the terrain you tackle, you can quickly identify which setup suits you best. This guide dives into the key advantages, terminology, and recommended SHIMANO GRX gearing configurations so you can make an informed choice.
Before comparing 1x and 2x, let’s clarify three key terms:
A 1x drivetrain is favored by riders looking for simplicity in their shift system. Shimano’s GRX 1x12-speed Di2 uses a 10–51T cassette paired with a single chainring (40T or 42T) for customizable range and step sizes.
A 2x drivetrain delivers the widest range and the smallest gear steps, perfect for riders who prioritize precise cadence control. GRX offers two chainring pairs (48/31T and 46/30T) that can be combined with SHIMANO 12-speed cassettes (11–30T, 11–34T, 11–36T).
Now, let’s take a closer look at gear steps and see how a rider’s speed changes when shifting between gears on a 1x and 2x setup.
For a 2x12-speed setup using GRX 48/31T chainrings and an 11-36T cassette, a rider pedaling at 100 RPM will travel at the following speeds when in the smallest three cogs on the cassette while in the big chainring:
This equates to a total speed difference of 6.7 MPH between the top three gears of the GRX 2x drivetrain system.
For a 1x12-speed setup using GRX 42T chainring and an 11-51T cassette, a rider pedaling at 100 RPM will travel at the following speeds when in the smallest three cogs on the cassette:
This equates to a total speed difference of 9.7 MPH between the top three gears of the GRX 1x drivetrain system. The bigger speed difference is due to the bigger steps between cog sizes (10T, 12T, 14T). This illustrates how 2x yields tighter spacing, while 1x offers broader jumps.
If all this math is making your head hurt, here are some tested and trusted gear combinations for different kinds of riders. Choose a proven configuration based on your goals, then fine-tune chainrings or cassettes as you dial in your ride.
Whether you relish the elegant simplicity of 1x or the nuanced control of 2x, Shimano’s GRX lineup has you covered. From high-speed racing to bikepacking expeditions, there’s a gearing solution that matches your terrain and riding style. Now, gear up, explore beyond the pavement, and enjoy every turn of the crank, no matter how many chainrings you choose.
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