What Gear Ratio You Need for Climbing, Based on Your Weight and Watts

For climbing you need gearing that lets you pedal at 70-75 rpm or more at the power you can sustain, and that depends mostly on the grade and your watts per kilo. A 165 lb (75 kg) rider on a 19 lb (8.6 kg) bike climbing an 8% grade at 200 W goes 6.2 mph (9.9 km/h): in a 34x28 that’s 64 rpm, in a 34x32 73 rpm and in a 34x34 78 rpm. If the climb has 10% pitches, at that same power they’d need about 22.6 gear inches (1.81 m), lower than any road 34x34.

Below are the tables at 150, 200 and 250 W on grades from 6 to 12%, the quick rule to work out your own case, and which drivetrain to choose for your fitness. To run the numbers for your bike, use the gear ratio calculator.

How it’s calculated

There are two steps:

1. Climbing speed. A physical model of cycling power (Martin and colleagues’, validated on the road in 1998) calculates how fast your watts move you, accounting for weight, grade, air resistance and rolling resistance. We use a 165 lb (75 kg) rider on a 19 lb (8.6 kg) bike (184 lb, or 83.5 kg, total), hands on the tops (aerodynamic drag area, or CdA, of 0.40 m²), normal pavement (rolling resistance coefficient of 0.0045), 2.5% drivetrain losses and no wind.
2. Cadence. Cadence (pedal revolutions per minute) is speed divided by how far the bike travels per pedal stroke. In U.S. terms, with gear inches:

Cadence (rpm) = speed (mph) × 336 ÷ gear inches

Gear inches are the chainring divided by the cog, times the wheel diameter in inches. In Europe, people use development instead: the meters the bike travels per pedal revolution. With 700x28 tires (about 2,125 mm circumference), the usual low gears are: 34x28 = 32.3 gear inches (2.58 m), 34x32 = 28.3 (2.26 m), 34x34 = 26.6 (2.12 m) and, on a 1x gravel bike, 40x44 = 24.2 (1.93 m). If gearing terms are new to you, start with bike gear ratios explained.

One fact explains everything else: climbing an 8% grade at 200 W, about 180 W goes into overcoming gravity, about 10 W into rolling resistance and only 5 W into the air. On a climb, weight rules, not aerodynamics.

Speed and cadence by grade and power

A 165 lb rider on a 19 lb bike. The last four columns are cadence, in rpm, in each combination (all with 700x28 tires):

For context: for a 165 lb rider, 150 W is 2.0 watts per kilogram of body weight (W/kg), 200 W is 2.7 W/kg and 250 W is 3.3 W/kg. See where you stand with the watts per kilo calculator. The watts that count are the ones you can hold for the whole climb, which on an hour-long climb are close to your FTP (the power you can sustain for about an hour); the FTP and power zones calculator helps you estimate it.

Rule of thumb: on long climbs, try not to drop below 70-75 rpm. Grand Tour pros climb at about 71 rpm on average, and they do it with far more power per kilo than an amateur. Below 60 rpm, every pedal stroke takes a lot of force and the climb feels endless.

What gearing you need

The table above in reverse: how many gear inches (and meters of development) you need to pedal at 75 rpm, with the figure for 70 rpm in parentheses.

The shortcut: at 75 rpm, the gear inches you need are your climbing speed in mph times 4.5. If you climb at 6.2 mph, 6.2 × 4.5 = 27.6 gear inches. At 70 rpm, multiply by 4.8. (In metric, divide your speed in km/h by 4.5 to get meters of development.)

Compare that with what each drivetrain gives you: a 34x28 is 32.3 gear inches, a 34x34 is 26.6, a 40x44 on a gravel bike 24.2 (25.0 with 40 mm tires), and a mountain bike with a 32T chainring and a 51T cog on 29 x 2.25 in tires goes down to 18.1 gear inches (1.44 m). That’s why the 14-18 gear inches that 10-12% pitches call for at 150 W only come from a mountain drivetrain. The figures for any other chainring and cog combination are in the gear development chart.

Recommendations by fitness level

For the same 165 lb rider on a 19 lb road or gravel bike:

In practice:

• If you have a 50/34 compact with an 11-28 or 11-30, you’re fine on 6-7% climbs from about 2.7 W/kg. For anything harder, the simplest change is usually an 11-34 cassette, as long as your rear derailleur can handle it.
• If you climb at under 2.5 W/kg or with panniers, look at gravel drivetrains: a 2x 48/31 with an 11-34 or 11-36 (Shimano GRX) or a 1x with a 40T chainring and a 10-44 (SRAM XPLR) or 10-45 (Shimano GRX) cassette. We compare them in 1x vs. 2x: which drivetrain to choose.
• The steepest pitch decides, not the average. A climb that averages 7% can have miles at 10%: the Lagos de Covadonga in Spain averages 7.4% with 15% pitches, and the Angliru 10.2% with pitches of 23.5%. Check the section-by-section profile in our climb pages.

Weight matters too

With 20 lb (9 kg) more in total (a 185 lb rider, or 165 lb with bikepacking gear), climbing 8% at 200 W you drop from 6.2 to 5.6 mph (9.0 km/h), and in the 34x34 you go from 78 to 71 rpm. With 35 lb less (a 130 lb rider on the same bike at the same 200 W) you climb at 7.5 mph (12.0 km/h) and a 34x28 works at 78 rpm.

That’s why the useful number is watts per kilo, not just watts: 200 W at 130 lb is a very different level from 200 W at 185 lb. If you’re carrying a load, calculate with your real total weight and look for gearing one step lower. How to raise those watts per kilo, by training or losing weight, is covered in the guide on how to climb faster.

How to choose your climbing gear in 5 steps

1. Work out the watts you can hold on a long climb. If you have a power meter, use your FTP or the average power from a 30-60 minute climb. If not, estimate it with the climb time calculator from your time on a climb you know, or compare your time with the climb times by W/kg chart.
2. Find the steepest sustained grade on the climb you want to ride: not the average, but the hardest mile.
3. Calculate your speed on that section at those watts and your total weight (rider, bike, clothes, bottles and bags). The same climb time calculator gives you that.
4. Multiply your speed in mph by 4.5 to get the gear inches that keep you at 75 rpm.
5. Compare it with your drivetrain in the gear ratio calculator and, if you’re short, find the cassette or chainrings that get you there. If it’s your first big climb, the guide on how to prepare for your first big climb helps with pacing and training.

Common mistakes

• Choosing pro gearing. Pros climb with far more power per kilo; at 2.5 W/kg the same climb calls for much lower gearing. There’s nothing wrong with a 34x34.
• Looking at the average grade. A climb that averages 6% with 11% pitches is ridden in the gear the pitches demand.
• Counting only your body weight. The bike, water, clothes and bag go up the hill with you: in our example, the bike alone is 19 lb.
• Standing up to make up for it. Standing helps on a short kicker, but it doesn’t replace a lower gear on a 40-minute climb.
• Changing the cassette without checking the chain or derailleur. A bigger cog usually needs more links: recalculate chain length and check the rear derailleur’s spec sheet for the largest cog it handles.

Updated October 19, 2026 ·Report an error on this page