Bike fit calculator
Fit the bike you already have. Tape, a hardcover book, and ten minutes — then unlock millimetre targets for saddle height, setback, and cockpit with Tiiks Pro. This is a starting point, not a studio Retül session.
Example: a 176 cm rider with an 83 cm cycling inseam and 172.5 mm cranks lands in the mid-73 cm neighbourhood for saddle height (BB to saddle, LeMond blended with Hamley). Exact millimetres are behind Pro so this page stays educational for search.
How a home bike fit actually works
Studio fits watch you pedal. A serious home fit is still a static model: measure the body, pick how aggressive you want to sit, compute contact points versus the bottom bracket, then fine-tune after a few rides. Set cleats first, then saddle height, then setback (layback), then the bars. Never slide the saddle to fix reach.
Saddle height (LeMond and Hamley)
LeMond estimates BB centre to saddle top as cycling inseam × 0.883. Hamley uses inseam × 1.09 from the pedal at bottom dead centre; subtract crank length to compare. We blend those, start a few millimetres low, and treat Holmes 25–35° knee bend as a check, not a third height formula. Too high is worse than too low: the pelvis rocks and the back complains.
Setback is not KOPS
The number that matters is horizontal millimetres from the bottom-bracket centre to the saddle nose. Knee-over-pedal-spindle is only a ballpark on-bike check, and shops disagree on which bump of the knee to drop from. Measure with a wall or two plumb lines: wall-to-BB minus wall-to-nose.
What this calculator does not do
No time-trial aerobars, no e-bike, no kids geometry, no diagnosis. A standing phone photo is a worse inseam than a book against a wall. Frame size is a sanity note later, not a bike shopper. Tire pressure and gear ratio stay free calculators; bike fit millimetres are Pro because they are the product.
FAQ
Is this a free bike fit calculator?
The measurement wizard is free on this page. Saddle height, setback, and reach in millimetres unlock with Tiiks Pro — the same plan as the iOS and Android app, including web checkout on tiiks.com/plans.
Do I need a new bike?
No. This fits the bike you already own: saddle height and setback, then stem and spacers. If the targets want an extreme stem, we will later note that the frame may be the wrong size — we do not pick a catalog bike for you.
What is cycling inseam?
Not trouser inseam. Stand barefoot against a wall, press a hardcover book up into the crotch like a saddle, mark the top of the book, measure floor to mark. A second person helps. Five millimetres of inseam error is about four millimetres of LeMond saddle height.
Road, gravel, MTB, and city?
Yes. Drop-bar road and gravel, flat-bar MTB, and upright hybrid or city. No e-bike mode and no time-trial mode.
Will this replace a professional bike fit?
No. If you have a known leg-length difference over a centimetre, spinal fusion, or a physio told you to get a studio fit, use this as a coarse start and see a fitter. Stop if pain gets worse.
Numbers are one ride. Wear is every ride. After the saddle is in the right place, Tiiks tracks chain, tyres, and service from Strava so the fit is not the last time you think about the bike.
All cycling tools