Bike Gear Ratios

It's how many times the rear wheel turns for one pedal revolution. A 4.0 ratio = three wheel turns per pedal stroke (a 'hard' gear for high speed). A 1.0 ratio = one wheel turn per stroke (a 'low' gear for steep climbs). Gear inches is the same concept normalised by wheel size, so you can compare gearing across road, gravel and MTB.

Gear inches expresses your gearing as the diameter (in inches) of an equivalent direct-drive wheel — higher means a harder gear. Development (metres rolled per pedal stroke) is how far you travel with one turn of the cranks. Both let you compare setups regardless of wheel size, which is why this calculator shows them alongside the raw ratio.

1× drivetrains (one chainring) are simpler, lighter, and shift cleanly under load — great for gravel and MTB. 2× setups (two chainrings) keep tighter spacing between gears, which matters on the road where you want to hold a precise cadence. Use the gear ratio calculator to compare any two setups.

On a road bike, an 11-32 or 11-34 cassette with a compact (50/34) crankset gives you a low-enough bailout for 10–12% grades. For sustained steep gravel and MTB, look at 10-44, 10-51 or 10-52 — these put the lowest gear below a 1.0 ratio, so you can spin 70 RPM at walking pace.