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Bike Speed Calculator

Calculate your cycling speed in km/h or mph instantly with our free online Bike Speed Calculator. Perfect for road, MTB, gear, and power-based biking.

W
kg/m³
Sea level: 1.225, High altitude: ~1.0
Positive: headwind, Negative: tailwind
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Cycling is not just a hobby or workout it's a science of speed, power, and precision. Whether you're riding a mountain bike, a road bike, or a hybrid, knowing your actual speed is crucial. That's why we built the Bike Speed Calculator an easy tool that helps you calculate your bike speed based on different inputs like wheel size, cadence, gear ratio, and more.

Whether you're training for a race, commuting daily, or just curious about how fast you're really going, this calculator is designed for simplicity and accuracy. No technical jargon, just straightforward results anyone can understand.

What Is a Bike Speed Calculator?

A Bike Speed Calculator is a tool that helps you determine how fast you’re cycling based on specific variables. It factors in your cadence (RPM), gear ratio, wheel diameter, and other important metrics to estimate your speed in kilometers per hour (km/h) or miles per hour (mph). For those who train seriously, it can also help you convert your power output (watts) into speed.

How to Use the Bike Speed Calculator

Using the calculator is super simple. Just enter the following details:

1. Wheel Size

You can choose your tire size in inches (e.g., 26", 27.5", 29") or in millimeters (e.g., 700c for road bikes). Wheel size affects how much ground you cover with each pedal rotation.

2. Cadence (RPM)

Cadence is how fast you’re pedaling measured in rotations per minute. A higher cadence usually means faster speed, but it depends on your gear.

3. Gear Ratio

This is calculated by dividing the number of teeth on the front chainring by the number of teeth on the rear cog. For example, a 50-tooth front and 12-tooth rear give a gear ratio of 4.16.

4. Power (Watts) – Optional

If you have a power meter, you can input your watts. The calculator will estimate your speed based on this energy output.

Once you input all the values, hit Calculate, and the calculator instantly shows your cycling speed in km/h and mph.

Bike Speed Formula (In Simple Terms)

Here’s the basic formula the calculator uses:

Speed (km/h) = Wheel Circumference (in meters) × Cadence (RPM) × Gear Ratio × 60 ÷ 1000

For mph, it adjusts by a conversion factor from kilometers to miles (1 km ≈ 0.621371 miles).

Wheel Circumference can be calculated as:

Circumference = Wheel Diameter × π (approximately 3.1416)

If you're entering power (watts), the calculator uses known cycling physics formulas to estimate speed based on resistance, body weight, and terrain, but that’s kept hidden for ease.

Example Calculation

Let’s say you’re using a 700c road bike with a wheel diameter of 0.7 meters, a cadence of 90 RPM, and a gear ratio of 4.

Step-by-step:

  • Circumference = 0.7 × 3.1416 = 2.19912 meters
  • Speed = 2.19912 × 90 × 4 × 60 ÷ 1000 = 47.58 km/h

So at 90 RPM in that gear setup, you’re traveling around 47.6 km/h pretty fast!

Is 20 MPH on a Bike Fast?

Yes! 20 mph (about 32 km/h) is considered a strong average for road cyclists. Recreational riders usually average around 15–18 mph (24–29 km/h), while pro racers can go well above 25 mph.

How Fast Is 25 MPH on a Bike?

25 mph (40.23 km/h) is very fast, often achievable by seasoned cyclists or during a sprint. On flat terrain with good aerodynamics, experienced cyclists can maintain this speed for short durations.

How Fast Is 90 RPM on a Bike?

It depends on your gear and wheel size. But using our earlier example, 90 RPM with a 4.0 gear ratio on a 700c bike can give you about 47–50 km/h. So yes, 90 RPM can mean serious speed if geared right.

Normal Cycling Speed in km/h

The average cycling speed for most casual riders is around 18 to 22 km/h. For mountain bikers (MTB), it's often slower due to rough terrain typically 10 to 15 km/h. Road bikers tend to be faster, averaging 25 to 30 km/h.

Final Verdict

The Bike Speed Calculator makes cycling data easy to understand for everyone from beginners to pro riders. Whether you're checking how fast you went on your last ride, optimizing your training cadence, or just playing with gear setups, this tool offers a fast and accurate answer.

FAQs

Can I use this calculator for my mountain bike?

Yes, it supports MTB-specific wheel sizes and gear ratios.

Does it work with watts input?

Absolutely. You can input your power (in watts) to estimate your speed if you use a power meter.

What is a good average speed for a beginner?

Anywhere between 15–20 km/h is great for beginners. Focus on consistency over speed.

Do I need to know my exact gear ratio?

It helps for accuracy, but you can estimate it if you're unsure.

Can I calculate distance too?

Yes! Combine speed and time using the formula:

Distance = Speed × Time