Choosing a 1× chainring for mixed road and gravel riding
A smaller chainring moves the entire gear range downward. It does not give you an extra climbing gear while leaving everything else untouched. Before choosing one for a mixed route, decide which end you actually need to change: the gear for the steep climb or the gear for the fast road section.
With the cassette unchanged, replacing 42T with 38T multiplies each ratio by 38/42, about 0.905. Every gear is roughly 9.5% lower. On an illustrative 10–44 cassette, the lowest ratio changes from 0.95 to 0.86 and the highest from 4.20 to 3.80. This is arithmetic, not a recommended combination for a specific crank or frame.
The cassette’s percentage jumps remain the same. You have shifted their location relative to road speed, not made the cassette more closely spaced. At the same speed in a corresponding gear, cadence must rise by the inverse ratio: 42/38, about 10.5%.
First consider a climb where the present lowest gear is too demanding. Calculate the change you want and compare it with the candidate ring. Then examine a fast section where you still pedal: are you already using the smallest rear sprocket, or do several higher gears remain? A ring selected from the downhill maximum on a computer file may solve a speed you usually reach while coasting.
The aim is a useful compromise for the whole route. If both ends are essential and a smaller ring loses the high gear you need, compare a different approved cassette or a complete 2× system instead of pretending the trade-off disappeared.
Confirm the replacement, not just its tooth count
An ICAN GRARO build still needs the correct crank interface, offset/chainline, chain specification and frame clearance. The current manufacturer page recommends no more than 42T for a single ring. That maximum is not proof that every smaller aftermarket ring fits the same crank.
Have the assembler use the matching component instructions to check installation and chain setup. Save the tooth counts you chose with your build record. Next time the gearing feels wrong, you will have a baseline more useful than “a medium-sized ring.”
