Calculators
Bike fit and geometry
- Bike Frame Size CalculatorEstimate road, gravel or MTB frame size in centimetres from inseam and height. Inseam sets the size; height only nudges the rounding.
- Stack and Reach Ratio CalculatorDivide frame stack by reach. Below 1.45 is race (under 1.35 very aggressive), from 1.45 up to 1.55 is a sporty all-rounder, and 1.55 or higher is upright endurance.
- Optimal Saddle Height CalculatorLeMond saddle height is 0.883 times inseam, measured from the centre of the bottom bracket to the top of the saddle.
- Handlebar Width CalculatorMatch road bar width to shoulder width and add 20 mm for gravel. A flat MTB bar is measured end to end: about 1.9 × shoulder width, kept within 720–800 mm.
- Crank Length CalculatorMap inseam to cranks from 160 to 177.5 mm in 2.5 mm steps, plus a shorter modern alternative.
- Stem Length and Angle CalculatorSee how stem length, stem angle and head tube angle add horizontal reach and vertical rise on top of frame reach.
- Cleat Fore-Aft CalculatorEstimate foot length from an EU shoe size and place the cleat centre near the ball of the foot.
Drivetrain and gearing
- Bicycle Gear Ratio CalculatorGear ratio is chainring teeth divided by cassette cog teeth. Compare the easiest and hardest gears for real chainring and cassette pairs.
- Gear Inches and Roll-out CalculatorConvert a chainring and cog plus wheel size into gear inches and metres travelled per pedal revolution.
- Optimal Chain Length CalculatorEstimate chain links from chainstay length, the largest chainring and the largest cassette cog. Rounded up to an even link count.
- Derailleur Capacity CalculatorTotal capacity is the chainring difference plus the cassette difference. See whether a short, medium or long cage is enough.
- Cadence to Speed CalculatorTurn cadence, chainring, cog and wheel size into speed. Roll-out per revolution times cadence gives km/h.
- Cassette Range CalculatorCassette range is the largest cog divided by the smallest, times 100. A 10–52 is 520%.
- Fixie Skid Patch CalculatorSkid patches are the cog divided by its greatest common divisor with the chainring. They double for either-foot skidders when the reduced chainring is odd.
Wheels and tires
- Tire Pressure CalculatorStarting tyre pressure from system weight, tyre width and surface. Front and rear are split, and hookless rims cap at 72.5 psi.
- Spoke Length CalculatorSpoke length from rim ERD, flange diameter, offset, spoke count and cross pattern. One side per calculation.
- Tubeless Sealant CalculatorEstimate tubeless sealant in millilitres from tyre width and bead-seat diameter. Wider tyres and 29-inch wheels take more fluid.
- Rim and Tire ETRTO CheckerCheck a tyre width against an inner rim width with the ETRTO 2024 table. A yes means that pairing is listed for the rim.
- Wheel Circumference CalculatorWheel circumference in millimetres from bead-seat diameter and tyre width. Use it to calibrate a speed sensor.
Suspension and MTB setup
- Fork Sag and PSI CalculatorSag in millimetres from travel and a target percent, plus a starting air pressure from rider weight.
- Rear Shock Spring Rate CalculatorEstimate a coil spring rate in lb/in from rider weight, leverage ratio, stroke and target sag.
- Brake Rotor Size CalculatorPick a front and rear rotor diameter from rider weight and discipline: road, gravel, trail, enduro or downhill.
- Flip-Chip Geometry CalculatorSee a typical flip-chip change: 0.5° slacker head angle and 6 mm lower bottom bracket in the low position.
Performance and e-bikes
- E-Bike Battery Range CalculatorEstimate e-bike range from battery watt-hours, assist level and average gradient. Uses 90% of the pack.
- Power-to-Weight CalculatorDivide functional threshold or peak watts by body weight in kilograms. The result is W/kg.
- Climbing VAM CalculatorVAM is elevation gained per hour. With body weight it also gives the power that lifts your body, the floor under your real climbing watts.
- Speed to Watts CalculatorEstimate steady-state watts from speed, drag area (CdA), weight, rolling resistance and gradient.
- Calories and Carbs CalculatorEstimate kilocalories from average watts and duration, and a carbohydrate target in grams per hour.
- Cost per Gram CalculatorDivide the price difference by the grams saved. At 5 per gram or less, in any currency, the flag says the upgrade is in a sane range.
- Bicycle Torque GuideCommon bicycle bolt torques in newton-metres for stems, seatposts, rotors, cranks, pedals and thru-axles.