1× or 2× for gravel: compare the gears you will actually use
A single chainring does not automatically mean a harder climbing gear. Two chainrings do not automatically mean twice as many useful choices. Start with the smallest and largest ratios, then look at the steps between them. The answer may be much closer than the drivetrain debate suggests.
Ratio means front teeth divided by rear teeth. This illustrative comparison uses a 40T ring with a 10–44 cassette and a 46/30 double with an 11–34 cassette. It assumes the same wheel rollout and does not describe a tested or approved complete build. Total range is the highest ratio divided by the lowest, multiplied by 100.
Illustrative gearing; rounded ratios
Setup
Lowest
Highest
Total range
40 × 10–44
40/44 = 0.91
40/10 = 4.00
440%
46/30 × 11–34
30/34 = 0.88
46/11 = 4.18
474%
Decide what the middle gears must do
Here the double reaches slightly lower and higher. That does not settle the choice. For steady road sections, inspect the actual sprocket sequence and the cadence changes between gears. For rough routes, decide whether avoiding front shifts is worth the particular gaps in your proposed cassette. Some ratios on a double overlap; simply multiplying chainrings by sprockets overstates the distinct choices.
ICAN’s GRARO page, rechecked October 22, 2026, describes 1× and 2× support but also restricts the frame to gravel groupsets, recommending maximum 42T single and 48/31T double rings. Check the exact crank, chainline, front-derailleur arrangement and tire clearance. The phrase “supports 2×” is not a complete compatibility list.
Write down your required low gear and the road gears you care about, then compare approved complete systems. That is a better starting point than choosing a side in an argument about how many rings a gravel bike ought to have.
