What does the gear calculator do?
GearCalculator is a gear ratio calculator, bike speed calculator and cadence calculator in one. For every combination of chainring and cog it shows how fast you ride at a given cadence – or, the other way round, which cadence you need at a given power in watts. It also calculates gear ratio, development (metres per crank revolution), gain ratio, gear inches, torque and average pedal force. Gradient, wind, weight, riding position, surface and altitude all feed into the power calculation.
Choose stock components from Shimano (Dura-Ace, Ultegra, 105, Tiagra, Sora, Claris, GRX, XTR, XT, SLX, Deore), SRAM (Red, Force, Rival, Apex, XPLR, Eagle) and Campagnolo (Super Record, Record, Chorus, Ekar), then swap individual chainrings or cogs – just like in the workshop.
Formulas: gear ratio, development and speed
- Gear ratio
- Chainring teeth ÷ cog teeth. Example: 50 × 17 = 2.94 – the rear wheel turns 2.94 times per crank revolution.
- Development
- Gear ratio × tyre circumference. 50 × 17 with 700 × 28c (2136 mm) gives 6.28 m per crank revolution. Every gear as a chart: gear development calculator.
- Speed
- Development × cadence × 60 ÷ 1000 = km/h. At 90 rpm in 50 × 17 that is about 33.9 km/h (21.1 mph).
- Gain ratio
- Gear ratio × wheel radius ÷ crank length (after Sheldon Brown). It also takes crank length into account: 50 × 17 gives 5.80 with 172.5 mm cranks and 6.06 with 165 mm.
- Power
- (Rolling resistance + gravity + air drag) × speed ÷ drivetrain efficiency (97.6 %). To calculate it without picking a gear: cycling power calculator.
Supported cranksets and cassettes
Shimano
Cranksets · Road 12-speed
- Dura-Ace FC-R9200 50/34
- Dura-Ace FC-R9200 52/36
- Dura-Ace FC-R9200 54/40
- Ultegra FC-R8100 50/34
- Ultegra FC-R8100 52/36
- 105 FC-R7100 50/34
- 105 FC-R7100 52/36
Cranksets · Road 11-speed
- Ultegra FC-R8000 50/34
- Ultegra FC-R8000 52/36
- Ultegra FC-R8000 53/39
- Ultegra FC-R8000 46/36 (CX)
- 105 FC-R7000 50/34
- 105 FC-R7000 52/36
- 105 FC-R7000 53/39
Cranksets · Road 10/9/8-speed
- Tiagra FC-4700 50/34
- Tiagra FC-4700 52/36
- Tiagra FC-4703 50/39/30
- Sora FC-R3000 50/34
- Sora FC-R3030 50/39/30
- Claris FC-R2000 50/34
- Claris FC-R2030 50/39/30
Cranksets · Gravel GRX
- GRX FC-RX820-2 48/31 (12-sp.)
- GRX FC-RX820-1 40 (12-sp.)
- GRX FC-RX820-1 42 (12-sp.)
- GRX FC-RX610-2 46/30 (12-sp.)
- GRX FC-RX810-2 48/31 (11-sp.)
- GRX FC-RX600-2 46/30 (11-sp.)
- GRX FC-RX810-1 40 (11-sp.)
Cranksets · MTB 12-speed
- XTR/XT/SLX/Deore 1x 30
- XTR/XT/SLX/Deore 1x 32
- XTR/XT/SLX/Deore 1x 34
- XTR/XT/SLX/Deore 1x 36
- XT FC-M8100-2 36/26
- XT FC-M8100-2 38/28
Cassettes · Road 12-speed
- Dura-Ace CS-R9200 11-30 (11-12-13-14-15-16-17-19-21-24-27-30)
- Dura-Ace CS-R9200 11-34 (11-12-13-14-15-17-19-21-24-27-30-34)
- Ultegra CS-R8100 11-30 (11-12-13-14-15-16-17-19-21-24-27-30)
- Ultegra CS-R8100 11-34 (11-12-13-14-15-17-19-21-24-27-30-34)
- 105 CS-R7101 11-34 (11-12-13-14-15-17-19-21-24-27-30-34)
- 105 CS-R7101 11-36 (11-12-13-14-15-17-19-21-24-27-31-36)
Cassettes · Road 11-speed
- Ultegra/105 11-25 (11-12-13-14-15-16-17-19-21-23-25)
- Ultegra/105 12-25 (12-13-14-15-16-17-18-19-21-23-25)
- Ultegra/105 11-28 (11-12-13-14-15-17-19-21-23-25-28)
- Ultegra/105 11-30 (11-12-13-14-15-17-19-21-24-27-30)
- Ultegra/105 11-32 (11-12-13-14-16-18-20-22-25-28-32)
- Ultegra/GRX CS-HG800 11-34 (11-13-15-17-19-21-23-25-27-30-34)
Cassettes · Road 10/9/8-speed
- Tiagra CS-HG500 11-25 (11-12-13-14-15-17-19-21-23-25)
- Tiagra CS-HG500 12-28 (12-13-14-15-16-17-19-21-24-28)
- Tiagra CS-HG500 11-32 (11-12-14-16-18-20-22-25-28-32)
- Tiagra CS-HG500 11-34 (11-13-15-17-19-21-24-28-31-34)
- Sora CS-HG400 11-25 (11-12-13-14-16-18-20-22-25)
- Sora CS-HG400 11-28 (11-12-14-16-18-20-22-25-28)
- Sora CS-HG400 11-32 (11-13-15-17-20-23-26-29-32)
- Sora CS-HG400 11-34 (11-13-15-17-20-23-26-30-34)
- Claris CS-HG50 11-28 (11-13-15-17-19-21-24-28)
- Claris CS-HG50 11-30 (11-13-15-18-21-24-27-30)
- Claris CS-HG50 11-32 (11-13-15-18-21-24-28-32)
- Claris CS-HG50 11-34 (11-13-15-18-21-24-28-34)
Cassettes · MTB / GRX 12-speed
- XTR/XT/SLX 10-45 (10-12-14-16-18-21-24-28-32-36-40-45)
- XTR/XT/SLX/Deore 10-51 (10-12-14-16-18-21-24-28-33-39-45-51)
SRAM
Cranksets · Road AXS 12-speed
- SRAM Red AXS 50/37
- SRAM Red AXS 48/35
- SRAM Red AXS 54/41
- SRAM Red AXS 56/43
- SRAM Force AXS 48/35
- SRAM Force AXS 46/33
- SRAM Force AXS 50/37
- SRAM Rival AXS 48/35
- SRAM Rival AXS 46/33
Cranksets · 1x Road/Gravel (XPLR)
- SRAM 1x 38
- SRAM 1x 40
- SRAM 1x 42
- SRAM 1x 44
- SRAM 1x 46
- SRAM 1x 48
Cranksets · MTB Eagle 12-speed
- SRAM Eagle 1x 30
- SRAM Eagle 1x 32
- SRAM Eagle 1x 34
- SRAM Eagle 1x 36
Cranksets · Road 11-speed
- SRAM Red/Force/Rival 22 50/34
- SRAM Red/Force/Rival 22 52/36
- SRAM Red/Force 22 53/39
- SRAM Apex/Rival 1 42
Cassettes · Road AXS 12-speed
- SRAM XG-1290/1270 10-26 (10-11-12-13-14-15-16-17-19-21-23-26)
- SRAM XG-1290/1270/1250 10-28 (10-11-12-13-14-15-16-17-19-21-24-28)
- SRAM XG-1270/1250 10-30 (10-11-12-13-14-15-17-19-21-24-27-30)
- SRAM XG-1290/1270 10-33 (10-11-12-13-14-15-17-19-21-24-28-33)
- SRAM XG-1270/1250 10-36 (10-11-12-13-15-17-19-21-24-28-32-36)
Cassettes · XPLR / Eagle 12-speed
- SRAM XPLR XG-1271/1251 10-44 (10-11-13-15-17-19-21-24-28-32-38-44)
- SRAM Apex PG-1231 11-44 (11-12-13-15-17-19-21-24-28-32-38-44)
- SRAM Eagle 10-50 (10-12-14-16-18-21-24-28-32-36-42-50)
- SRAM Eagle / Transmission 10-52 (10-12-14-16-18-21-24-28-32-36-42-52)
Cassettes · 11-speed
- SRAM PG-1170/1130 11-28 (11-12-13-14-15-17-19-21-23-25-28)
- SRAM PG-1170/1130 11-32 (11-12-13-14-16-18-20-22-25-28-32)
- SRAM PG-1130 11-36 (11-12-13-15-17-19-22-25-28-32-36)
- SRAM PG-1130 11-42 (11-13-15-17-19-22-25-28-32-36-42)
Campagnolo
Cranksets · 12-speed
- Campagnolo Super Record Wireless 48/32
- Campagnolo Super Record Wireless 50/34
- Campagnolo Super Record Wireless 52/36
- Campagnolo Record 12 50/34
- Campagnolo Record 12 52/36
- Campagnolo Record 12 53/39
- Campagnolo Chorus 12 48/32
- Campagnolo Chorus 12 50/34
Cranksets · Ekar 13-speed
- Campagnolo Ekar 38
- Campagnolo Ekar 40
- Campagnolo Ekar 42
- Campagnolo Ekar 44
Cranksets · 11-speed
- Campagnolo Chorus/Potenza/Centaur 50/34
- Campagnolo Chorus/Potenza 52/36
- Campagnolo Chorus/Potenza 53/39
Cassettes · 12-speed
- Campagnolo Record/Chorus 12 11-29 (11-12-13-14-15-16-17-19-21-23-26-29)
- Campagnolo Record/Chorus 12 11-32 (11-12-13-14-15-16-17-19-22-25-28-32)
- Campagnolo Chorus 12 11-34 (11-12-13-14-15-16-17-19-22-25-29-34)
Cassettes · Ekar 13-speed
- Campagnolo Ekar 9-36 (9-10-11-12-13-14-16-18-20-23-26-30-36)
- Campagnolo Ekar 9-42 (9-10-11-12-13-14-16-18-21-24-28-33-42)
- Campagnolo Ekar 10-44 (10-11-12-13-14-16-18-20-23-26-30-36-44)
Cassettes · 11-speed
- Campagnolo 11-speed 12-27 (12-13-14-15-16-17-18-19-21-24-27)
- Campagnolo 11-speed 11-29 (11-12-13-14-15-17-19-21-23-26-29)
- Campagnolo 11-speed 11-32 (11-12-13-14-15-17-19-22-25-28-32)
Frequently asked questions
What is a gear calculator?
A bike gear calculator shows what a combination of chainring and cog means on the road: gear ratio, development and speed at a given cadence. With GearCalculator you compare complete Shimano, SRAM and Campagnolo cassettes, swap individual cogs and instantly see which gears change and how many watts you need.
How do you calculate the gear ratio of a bike?
The gear ratio is the number of chainring teeth divided by the number of cog teeth. For 50 × 17 it is 2.94: the rear wheel turns 2.94 times per crank revolution.
What is development (metres of development)?
Development is the distance the bike travels per crank revolution: gear ratio × tyre circumference. With 50 × 17 and a 700 × 28c tyre (2136 mm circumference) that is 6.28 m.
How fast do I ride at 90 rpm?
Speed in km/h = development × cadence × 60 ÷ 1000. In 50 × 17 with a 28 mm tyre, 90 rpm gives about 33.9 km/h (21.1 mph). The calculator shows this for all gears at once in the gear table.
How many watts do you need for 30 km/h?
It depends mainly on air drag, weight and gradient. A 75 kg rider on an 8.5 kg road bike needs about 150 W for 30 km/h (18.6 mph) on the flat, without wind and riding on the hoods, around 220 W for 35 km/h and about 310 W for 40 km/h.
Which cassette do I need for steep climbs?
What matters is the easiest gear. With 34 × 34 at 70 rpm you ride at about 9 km/h; on a 10 % gradient a 75 kg rider on an 8.5 kg bike needs about 220 W for that. With 34 × 30 it is 10.2 km/h and about 250 W at the same cadence. In the gear calculator you set weight and gradient and see the required power for every cog.
What difference does crank length make?
A longer crank gives more leverage: the same gear feels easier and the gain ratio drops. Shorter cranks open the hip angle and are becoming popular for aero positions, but need slightly easier gears or a higher cadence. Common lengths are 165 to 175 mm.
What is gain ratio?
Gain ratio (after Sheldon Brown) relates the distance the bike travels to the distance the pedal travels. Unlike the plain gear ratio it accounts for wheel size and crank length, so gears on different bikes become directly comparable.
What is cross-chaining?
Cross-chaining happens when the chain runs diagonally – big chainring with the largest cogs or small chainring with the smallest cogs. It increases wear and friction. In the calculator these gears are hatched in the table.
Can I swap individual cogs and chainrings?
Yes. Chainrings can usually be swapped within the same bolt circle diameter, and many cassettes are available as single cogs or cog blocks. With “Customise” you set your own tooth counts and get notes on derailleur capacity, front derailleur and freehub.
Are Shimano, SRAM and Campagnolo cassettes compatible?
Shimano and SRAM largely share the same cog spacing up to 11-speed. At 12-speed the freehubs differ (Shimano HG/Micro Spline, SRAM XD/XDR). Campagnolo has its own freehub and cog spacing, so mixing is usually not compatible.