Bike Speed Calculator
Enter your cadence, chainring size, rear cog size and wheel dimensions to find your cycling speed instantly. Flip to the cadence-solving mode to find out how fast you need to pedal to reach a target speed. Switch between km/h and mph at any time.
How bike speed is calculated
Your cycling speed depends on three things: how fast you pedal (cadence in RPM), the mechanical advantage of your gear (chainring teeth divided by rear cog teeth, called the gear ratio), and the distance your rear wheel travels per full revolution (wheel circumference). The formula is: Speed = (Cadence / 60) x Gear Ratio x Wheel Circumference, where dividing by 60 converts RPM to revolutions per second and the circumference is measured at the tyre outer edge. Wheel circumference is pi multiplied by the outer diameter, which equals the rim bead-seat diameter plus twice the tyre section width. A 700c rim (622 mm) with a 25 mm tyre has an outer circumference of about 2117 mm, or 2.117 m.
Gear ratio, gear inches and rollout
The gear ratio is simply chainring teeth divided by rear cog teeth. A 50/17 combination gives a ratio of 2.94:1, meaning the rear wheel turns 2.94 times for each full pedal stroke. Gear inches is an older way to express the same idea: it multiplies the ratio by the wheel outer diameter in inches, and roughly represents the diameter of a high-wheel penny-farthing that would cover the same ground per revolution. Rollout (or development) is even more practical: it is the gear ratio multiplied by the wheel circumference, giving the exact distance covered per crank revolution. On a 700c/25 mm wheel with a 50/17 gear, rollout is about 6.22 m per stroke, meaning at 90 RPM you advance 9.33 m every second, or 33.6 km/h.
Cadence and why it matters
Cadence is the number of times you complete a full pedal revolution per minute. Research consistently shows that most trained cyclists work most efficiently between 80 and 100 RPM. Higher cadences shift the load from your muscles to your cardiovascular system, which recovers faster; lower cadences put more strain on leg muscles and joints, increasing fatigue over long distances. Beginners often pedal at 50-70 RPM using harder gears, which feels powerful but leads to earlier muscle burnout. Gradually increasing cadence while lowering gear resistance is a common training goal. The cadence-solving mode in this calculator helps you identify which gear to select before a climb or time trial so you can maintain your preferred RPM.
Choosing the right gear for your ride
Road cyclists commonly use compact (50/34T) or standard (53/39T) chainrings paired with cassettes spanning 11-28T to 11-34T. Gravel and adventure bikes favour 40-46T chainrings with wide-range 10-42T cassettes for steep terrain. Mountain bikes use 28-36T single chainrings with 10-52T cassettes. For any given target speed and preferred cadence, this calculator reveals exactly which gear combination is needed. If the required cadence is above 110 RPM, consider a harder gear; below 60 RPM, an easier one. Tyre width affects speed by a small but measurable amount: a wider tyre increases circumference and thus distance per revolution, nudging speed up slightly at the same cadence.
Typical cadence ranges by rider type
| Rider type / situation | Typical cadence (RPM) | Notes |
|---|---|---|
| Beginner recreational | 50-65 | Often uses higher gears at lower cadence |
| Intermediate recreational | 65-80 | Improving efficiency with practice |
| Endurance-trained cyclist | 80-95 | Sweet spot for power and muscle fatigue |
| Elite road racer | 90-110 | High cadence reduces muscle stress on long climbs |
| Track sprinter (peak effort) | 110-140+ | Short bursts only, extremely high power |
| Climbing at moderate grade | 70-85 | Lower cadence common on steep ascents |
| Time trial / triathlete | 85-100 | Steady aero position favours consistent cadence |
Pedaling cadence guidelines commonly cited by cycling coaches and exercise science research.
Frequently asked questions
What is the formula for calculating bike speed?
Speed = (Cadence in RPM / 60) x Gear Ratio x Wheel Circumference. Gear ratio is chainring teeth divided by rear cog teeth. Wheel circumference in metres is pi x (rim bead-seat diameter + 2 x tyre section width) / 1000. The result is in m/s, then multiplied by 3.6 for km/h or divided by 0.44704 for mph.
What cadence should I be aiming for?
Most cycling coaches and sports science studies recommend 80-100 RPM for sustained endurance riding. This range balances muscular stress against cardiovascular demand. Sprinters may exceed 110-130 RPM for short bursts, while climbers on steep gradients often drop to 70-80 RPM. Beginners commonly ride at 50-70 RPM and benefit from gradually raising cadence while shifting to an easier gear.
How does wheel size affect bike speed?
A larger wheel has a greater circumference, so it covers more ground per revolution. At the same cadence and gear ratio, a 700c wheel travels about 5-8% farther per stroke than a 26-inch wheel, making it measurably faster. Tyre width also plays a small role: a 28 mm tyre has a circumference about 0.3% larger than a 23 mm tyre on the same 700c rim.
What are gear inches and why are they useful?
Gear inches is a historical measure that converts your gear ratio to the equivalent diameter of a high-wheel (penny-farthing) bicycle. A higher number means a harder, faster gear. Modern road cyclists commonly use gears between about 40 and 110 gear inches. The advantage over gear ratio alone is that gear inches accounts for wheel size, letting you compare gearing across different bike types.
How do I find the cadence I need to reach a target speed?
Switch the calculator to Cadence mode, enter your target speed and current gear (chainring, cog and wheel size). The formula rearranges to: Cadence (RPM) = Target speed (m/s) / (Gear Ratio x Wheel Circumference) x 60. The calculator does this instantly and tells you whether the result is within a healthy cadence range for your gear.
Does tyre pressure affect calculated speed?
This calculator uses tyre section width to estimate circumference, which does not change with pressure. In reality, lower tyre pressure causes the tyre to bulge slightly, reducing the effective rolling radius by a small amount and fractionally lowering real-world speed. For the purposes of gear and cadence planning, the formula used here is accurate enough for all practical decisions.