UseCalcPro
Home
MathFinanceHealthConstructionAutoPetsGardenCraftsFood & BrewingTools
Blog
  1. Home
  2. Health

Bike Gear Ratio Calculator

Calculate speed and gear ratios for your bike

50T / 17T

2.94

Speed

20.7 mph

Development

20.27ft

Gear Inches

77.4"

Unit System

Gear Ratio

2.94

Medium-High

Speed @ 90 RPM

20.7

mph

33.4 km/h

Development

20.27

ft

per revolution

Gear Inches

77.4"

Speed at Different Cadences

60 RPM13.8 mph
75 RPM17.3 mph
90 RPM20.7 mph
100 RPM23 mph
110 RPM25.3 mph

Example Calculations

1Road Bike Cruising: 50T/17T at 90 RPM (700c)

Inputs

Chainring50T
Rear Cog17T
Wheel Size700c (2.1m circumference)
Cadence90 RPM

Result

Gear Ratio2.94
Speed33.4 km/h (20.7 mph)
Development6.18m per revolution
Gear Inches77.4"

Ratio = 50 / 17 = 2.94. Development = 2.1m x 2.94 = 6.18m. Speed = (6.18 x 90 x 60) / 1000 = 33.4 km/h. This is a "Medium-High" gear, suitable for flat-road cruising.

2Climbing Gear: 34T/28T at 80 RPM (700c)

Inputs

Chainring34T
Rear Cog28T
Wheel Size700c (2.1m circumference)
Cadence80 RPM

Result

Gear Ratio1.21
Speed12.2 km/h (7.6 mph)
Development2.55m per revolution
Gear Inches32.0"

Ratio = 34 / 28 = 1.21. Development = 2.1m x 1.21 = 2.55m. Speed = (2.55 x 80 x 60) / 1000 = 12.2 km/h. This is a "Low (Climbing)" gear, ideal for steep hills.

Frequently Asked Questions

Q

What is a good gear ratio for a road bike?

Road bikes typically use ratios from 1.0 (climbing) to 4.5 (fast flats). A 50/34 crankset with 11-28 cassette gives ratios of 1.21 to 4.55. Choose based on terrain - hillier routes need lower gearing.

  • Flat terrain: 50/15 to 50/11 (ratios 3.3–4.5) for 35–50 km/h cruising
  • Rolling hills: 50/19 to 34/21 (ratios 1.6–2.6) covers most recreational riding
  • Steep climbing (8%+ grade): 34/28 or 34/32 (ratio 1.06–1.21) saves your knees
  • Compact crankset (50/34) is the most versatile setup for 90% of riders
SetupGear RangeBest For
50/34 + 11-281.21–4.55All-around road riding
52/36 + 11-301.20–4.73Racing with moderate hills
46/30 + 11-340.88–4.18Gravel and steep terrain
32T (1×) + 10-520.62–3.20Mountain biking
Q

How do I calculate gear ratio?

Gear ratio = front chainring teeth ÷ rear cog teeth. For example, 50 front ÷ 25 rear = 2.0 ratio. Higher ratios are harder to pedal but faster. Lower ratios are easier for climbing.

  • A ratio of 2.0 means the rear wheel turns twice per pedal revolution
  • Road bike ratios typically range from 1.0 (easiest) to 4.5+ (hardest)
  • MTB ratios are lower, usually 0.6–3.2, for technical terrain
  • Gear inches = ratio × wheel diameter; 700c has ~26.3" effective diameter
Q

What is gear development?

Gear development (or meters development) is the distance traveled per pedal revolution: wheel circumference × gear ratio. A 700c wheel with 2.0 ratio travels about 4.3 meters per crank turn.

  • 700c wheel circumference is approximately 2.1 m (2,100 mm)
  • Top gear development on a road bike: 50/11 = 9.55 m per pedal turn
  • Comfortable cruising: 5–7 m development at 85–95 RPM = 25–40 km/h
  • MTB 29" wheel circumference is approximately 2.3 m, adding ~10% more distance per revolution
Q

What cadence should I maintain?

Most cyclists are efficient at 80-100 RPM. Pro racers often spin 90-110 RPM. Lower cadence (60-80) uses more muscle strength, higher cadence (90+) relies more on cardiovascular fitness.

  • Beginner target: 70–85 RPM; build up to 90+ over several months
  • Climbing cadence: 60–80 RPM in a low gear protects knee joints
  • Time trial cadence: 95–105 RPM balances power and aerobic efficiency
  • Sprint cadence: pros exceed 120 RPM in short bursts for maximum speed
  • Use a cadence sensor ($15–30) to monitor and train optimal RPM
Q

How does wheel size affect gearing?

Larger wheels travel farther per revolution, so they're effectively "higher" gearing. A 29" MTB with the same ratio as a 26" bike will be faster but harder to pedal. Adjust gearing to compensate.

  • 26" wheel: ~2,026 mm circumference – lowest effective gearing
  • 27.5" (650B): ~2,168 mm circumference – 7% higher than 26"
  • 29" (700c MTB): ~2,295 mm circumference – 13% higher than 26"
  • 700c road (23mm tire): ~2,096 mm; with 28mm tire: ~2,136 mm
  • Wider tires add 1–2% more circumference per 5 mm tire width increase
Wheel SizeCircumferenceDevelopment at 2.0 Ratio
26"2,026 mm4.05 m per rev
27.5" (650B)2,168 mm4.34 m per rev
29" / 700c2,295 mm4.59 m per rev

Related Calculators

Running Pace Calculator

Calculate your running pace

Calories Burned Calculator

Cycling calories burned

Heart Rate Zones

Training zone calculator

Unit Converter

Convert km to miles

BMI Calculator

Check your BMI and see which weight category you fall into based on WHO standards. View health ranges, get personal recommendations, and track your metrics.

BMR Calculator

Find out how many calories your body burns at rest with the Mifflin-St Jeor equation. Enter age, weight, and height to see your BMR and daily targets.

Related Resources

BMI Calculator

Calculate your body mass index

Calorie Calculator

Find your daily calorie needs

TDEE Calculator

Calculate total daily energy expenditure

More Fitness Calculators

Other fitness and health calculators

View All

Last Updated: Mar 9, 2026

This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

UseCalcPro
FinanceHealthMath

© 2026 UseCalcPro