Last updated: July 16, 2026
Bike Speed Calculator
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Quick Answer
The Bike Speed Calculator computes cycling speed using the formula v = π × (d + 2t) / 1000 × (N_c / N_g) × RPM / 60 × 3.6, where d is rim diameter in mm, t is tyre width in mm, N_c and N_g are chainring and cog teeth counts, and RPM is cadence. It also calculates gear ratio, wheel circumference, distance per pedal stroke, and classifies the speed into categories from Leisurely to Elite.
To calculate bike speed, multiply the wheel circumference in metres by the gear ratio and the cadence in RPM, then divide by 60 and multiply by 3.6 to get kilometres per hour. Wheel circumference equals pi times the sum of the rim diameter plus twice the tyre width, divided by 1000.
Key Takeaways
- Bike speed equals wheel circumference times gear ratio times cadence — all three factors multiply together, so doubling any one doubles your speed.
- A 700c road wheel (622mm rim) with a 23mm tyre has a circumference of 2.099 m; wider tyres slightly increase this.
- The optimal cadence for sustained road cycling is 85-100 RPM, balancing muscular endurance and cardiovascular efficiency.
- Gear ratio = chainring teeth / cog teeth; a 50/11 sprinting gear produces 4.55× more wheel revolutions per pedal stroke than a 34/11 climbing gear.
- Professional track sprinters can exceed 70 km/h using a fixed-gear development of 8.5+ metres per pedal stroke.
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Formula
v = π × (d + 2t) / 1000 × (N_c / N_g) × RPM / 60 × 3.6
Where:
- v=Speed(km/h)
- d=Wheel rim diameter(mm)
- t=Tire cross-section width(mm)
- N_c=Chainring tooth count(teeth)
- N_g=Cog tooth count(teeth)
- RPM=Cadence(rev/min)
Worked Examples
Recreational Road Cyclist
A recreational rider on a 700c road bike with a 50/16 gear and 75 RPM cadence.
- 1Wheel circumference: C = π × (622 + 2×23) / 1000 = π × 668 / 1000 = 2.0988 m
- 2Gear ratio: GR = 50 / 16 = 3.125
- 3Speed: v = 2.0988 × 3.125 × 75 / 60 × 3.6 = 29.51 km/h
Club Cyclist on Training Ride
An experienced cyclist riding a 50/14 gear at 90 RPM cadence on a 700c/25mm setup.
- 1Wheel circumference: C = π × (622 + 2×25) / 1000 = π × 672 / 1000 = 2.1111 m
- 2Gear ratio: GR = 50 / 14 = 3.571
- 3Speed: v = 2.1111 × 3.571 × 90 / 60 × 3.6 = 40.64 km/h
Mountain Bike Climbing
An MTB rider climbing in a low 34/28 gear at 70 RPM on a 29-inch wheel (622mm rim, 50mm tyre).
- 1Wheel circumference: C = π × (622 + 2×50) / 1000 = π × 722 / 1000 = 2.2682 m
- 2Gear ratio: GR = 34 / 28 = 1.214
- 3Speed: v = 2.2682 × 1.214 × 70 / 60 × 3.6 = 11.48 km/h
Introduction
The Bike Speed Calculator computes your cycling speed from three measurable inputs: pedaling cadence (RPM), wheel and tyre geometry, and your gear selection. Understanding how these variables interact lets you optimise your drivetrain for target speeds, choose the right gearing for a route, and assess your training progress. Whether you ride a road bike, gravel bike, or mountain bike, the same physics governs how fast your wheels spin across the ground.
How Bike Speed is Calculated
Cycling speed follows directly from three mechanical quantities. First, the wheel circumference — the distance the bike travels per wheel revolution — is determined by the total wheel diameter including the tyre: C = π × (d + 2t) / 1000 metres, where d is the rim diameter and t is the tyre cross-section, both in mm. Second, the gear ratio (N_c / N_g) tells you how many wheel revolutions occur per pedal revolution. Third, multiplying circumference, gear ratio, and cadence gives wheel revolutions per minute, which converts to km/h by multiplying by 60/1000 × 3.6. This formula is validated against real-world GPS data and matches the approach used in professional cycling software such as Golden Cheetah. For cadence measurement tools, try the bike cadence calculator.
Understanding Cadence
Cadence is the number of complete crank revolutions per minute. Research by Lucia et al. (2001) found that professional Tour de France riders averaged 89-95 RPM during mountain stages, while recreational cyclists typically sustain 60-80 RPM. Higher cadence reduces muscular fatigue and joint stress at the cost of higher cardiovascular demand — a tradeoff codified in the principle of neuromuscular efficiency. A cadence between 85-100 RPM is widely recommended for endurance cycling. To maintain a target speed at lower effort, raise your cadence rather than your gear. Pair this calculator with the cycling power zones calculator to understand how cadence affects energy expenditure.
Gear Ratios Explained
The gear ratio equals chainring teeth divided by cog teeth. A 50/16 combination gives a ratio of 3.125, meaning the rear wheel completes 3.125 revolutions per pedal stroke. Higher ratios produce more speed at the same cadence but require greater muscular force. The classic development metric (wheel circumference × gear ratio) tells you the distance covered per pedal stroke — useful for comparing gearing across bikes with different wheel sizes. Road racing cassettes typically cover ratios from 0.96 (34/36 climbing) to 4.82 (53/11 sprinting). According to the Sheldon Brown gear calculator, a 53/11 sprinting gear at 120 RPM yields 86 km/h — consistent with professional sprint speeds.
Wheel Size and Tyre Width
Modern road bikes use 700c wheels (622mm ETRTO rim diameter), while mountain bikes commonly run 29-inch (also 622mm rim), 27.5-inch (584mm), or 26-inch (559mm) wheels. A wider tyre adds to the total wheel diameter and thus slightly increases speed for the same gear and cadence — a 25mm tyre rolls 0.6% faster than a 23mm tyre in the same gear. Tyre pressure and rolling resistance also matter: according to Bicycling Science (Wilson, 2004, MIT Press), rolling resistance accounts for roughly 10-20% of total resistance at speeds below 25 km/h. For fitting the right bike size, see the bike size calculator.
Speed Categories for Cyclists
Cycling speed is often classified by effort level. Leisurely rides below 15 km/h suit beginners and urban commuting. Moderate cycling (15-25 km/h) is typical for regular recreational riders and fitness cycling. Fast cycling (25-35 km/h) characterises club riders and sportive participants. Very fast speeds (35-45 km/h) are achieved by competitive amateurs and semi-professional riders. Elite speeds above 45 km/h are sustained only by professional road racers or track cyclists on specialised equipment. The UCI World Hour Record, set by Filippo Ganna in 2022 at 56.792 km/h, defines the outer boundary of human cycling performance. Use the cycling wattage calculator to understand the power needed for each category.
Practical Applications and Optimisation
Use this calculator before a race or sportive to pre-select gears that match your target speed at your comfortable cadence. For a 40 km/h average on a 700c/25mm bike at 90 RPM, you need a gear ratio of approximately 3.17 — achieved with a 50/16 (3.125) or 52/16 (3.25) combination. To climb a mountain pass at 10 km/h with a 29-inch MTB at 70 RPM, a ratio around 1.05 (34/32) is appropriate. Track cyclists optimise gear development (circumference × ratio) rather than ratio alone because fixed-gear bikes have no derailleurs. According to British Cycling coaching guidelines, the optimal cadence range for road cycling is 85-95 RPM, balancing neuromuscular economy and cardiovascular efficiency.
Quick Reference Card
Bike Speed Quick Reference
Quick reference • Bike Speed Calculator
v (km/h) = π × (d + 2t) / 1000 × (N_c / N_g) × RPM / 60 × 3.6Valid range: Cadence 30-220 RPM; wheel diameter 300-900 mm; gear ratio 0.5-6.0
Common Values
⚠ Watch Out
- •Enter rim diameter (ETRTO bead seat diameter), not total tyre outer diameter.
- •Cadence above 140 RPM is only achievable on a track bike in a sprint; sustained values are typically 80-100 RPM.
- •Results assume zero slippage and constant cadence; GPS speeds may differ by 1-3%.
- •Gear ratio alone does not determine difficulty — combine with cadence and power output for a full picture.
Pro Tips
- →To maintain the same speed while reducing effort, shift to a smaller cog (higher gear ratio) and increase cadence.
- →For climbing, target a gear ratio below 1.5 to keep cadence above 60 RPM.
- →Cross-chaining (big chainring + big cog) wears the chain rapidly — stay within a ±3 cog range of the chainring.
- →When comparing bikes with different wheel sizes, use the development metric (C × GR) rather than gear ratio alone.
FAQs
What is cadence and why does it matter?
Cadence is the number of complete pedal revolutions per minute (RPM). It directly multiplies wheel circumference and gear ratio to produce speed. A higher cadence at the same speed means a lower (easier) gear, which reduces muscular strain on the knees and legs. Most cycling coaches recommend 80-100 RPM for sustained road riding.
How does gear ratio affect cycling speed?
Gear ratio = chainring teeth / cog teeth. A higher ratio means the rear wheel completes more revolutions per pedal stroke, producing greater speed at the same cadence. For example, shifting from 50/16 (3
- 1to 50/14 (3
- 2increases speed by 14.3% at the same RPM
What is the standard 700c wheel diameter in mm?
The 700c tyre designation refers to a rim with an ETRTO bead seat diameter of 622mm. This is by far the most common road and gravel bike wheel size. The total wheel diameter including the tyre varies from 668mm (23mm tyre) to 682mm (30mm tyre).
How do I calculate the distance I travel per pedal stroke?
Distance per stroke = wheel circumference (m) × gear ratio. For a 700c/25mm wheel (C ≈ 2.11 m) with a 50/16 gear (GR = 3.125), each pedal stroke advances the bike 2.11 × 3.125 = 6.59 metres.
Why is my GPS speed different from the calculator result?
The calculator gives theoretical mechanical speed assuming no slippage and circular wheel geometry. Real GPS speed reflects actual ground motion including tyre deformation, slight slippage, and terrain variations. Differences of 1-3% are normal; larger discrepancies usually indicate incorrect input values (especially wheel diameter or tyre size).
What gear ratio is best for climbing hills?
For steep climbs (grades above 10%), a gear ratio below 1.5 is typically needed. Road bikes with compact cranks (34/50) paired with 11-34 cassettes achieve a minimum ratio of 1.0 (34/34). Mountain bikes go even lower — 28/42 (0.67) for technical climbing. The appropriate climbing gear depends on fitness, grade, and load.