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Bike fit calculator
Fit the bike to your body
2 minutes, 2 body measurements — you'll get saddle height (3 methods), setback, handlebar drop, crank length and frame geometry. Every number with its scientific source. No account; data stays in your browser.
How and why do you ride?
Comfort = higher and closer; performance = lower and longer, if your body allows.
Your measurements
How to measure your inseam: stand barefoot with your back to a wall, press a hardcover book firmly into your crotch (like a saddle), spine against the wall. Measure floor → top edge of the book. Measure twice.Fine-tune (optional) — narrows the ranges
bony points at the top of your shoulders (AC), centre to centre
cardboard measurement — instructions with the result
Flexibility — a 10-second test
Stand straight, feet together, and slowly bend forward with straight knees. How far do you reach?
Anything bothering you on the bike?
Select all that apply — we'll adjust the ranges. This is not a diagnosis.
Current setup (optional)
Fill this in and we'll show exactly how much to change.
BB centre → top of saddle, along the seat tube
stamped on the inner face of the crank arm
An educational tool, not a medical device · Your result is a starting point · methodology & sources
What this calculator computes — and on what evidence
This is a free bike fit calculator built on peer-reviewed research rather than folklore. From two body measurements it computes saddle height three ways — the Holmes knee-angle method (25–35°), the LeMond 88.3%-of-inseam rule and the Hamley 109% rule — and anchors the recommendation on the knee angle, because formulas alone miss the reference window in 73% of riders (Peveler & Green, 2011).
You also get saddle setback (with the KOPS convention explained and critiqued), handlebar drop matched to your flexibility test and experience, crank length per the modern evidence (power barely changes across 120–220 mm — Martin & Spirduso, 2001), handlebar and saddle width, cleat position, and a frame reach/stack target for your next bike. Every number is a range with a "Why this result?" section: the method, the modifiers applied to you, and citations graded as systematic review, peer-reviewed study, or practitioner convention.
When you're done, verify the one number that matters most — your real knee angle in motion — with the live camera check. Want the background first? Start with how to set your saddle height or browse all guides.