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Free · In your browser · Private
Fit the bike to your body.
Not the other way round.
Enter two body measurements — get saddle height, setback, bar drop and crank length computed with methods from peer-reviewed research, each number with its range and its source. Then verify your real knee angle live with your phone camera.
No account · Nothing uploaded — everything runs on your device · Not a medical device
Your result — preview
road · 178 cmAn interactive diagram with your measurements — every number explained and cited.
$0
calculator & camera check — always
2 min
from measurements to a full result
22
references in the methodology
100%
computed on your device
One fit. The right tool at each step.
Start broad with a full Fit Plan, measure movement with the camera, or answer one equipment question without repeating the entire intake. Every route leads back to a controlled, one-change-at-a-time check.
Calculator — start from science
Height + inseam, your goal, flexibility and any aches → saddle height by three methods (Holmes, LeMond, Hamley), setback with the KOPS critique, bar drop matched to your mobility, crank length per current research, frame reach/stack for your next bike.
Calculate now →
Camera — measure for real
Prop up your phone, hop on, pedal. We measure your knee, hip and trunk angles in real time — in the browser, no video uploaded. It's the verification no formula can give you: your own proportions, in motion.
Measure yourself →
New · 2 min after two fits
Compare camera dates
Compare two confirmed dates only when the same bike setup and camera protocol are frozen for both.
Open tool →Updated · 8–12 min + ridesRun a crank swap trial
Compare two crank lengths, then freeze the result against one bike and carry it through mechanic installation and a measured ride re-check.
Open tool →Updated · 5–10 minTrack each bike
Capture repeatable coordinates and exact component identities, then group every adjustment and follow-up by bike.
Open tool →New · 4–8 minPrepare a mechanic hand-off
Turn frozen local adjustment plans and exact component references into one print-ready workshop hand-off.
Open tool →New · 8–12 minPlan a stem or spacer trial
Freeze the current cockpit, model one spacer move or mechanic-installed stem change, then verify the installed coordinates.
Open tool →Want the full workup? The guided fit walks you from intake and a safety check through video analysis to a printable report — about 15 minutes with your bike on a trainer. Browse all tools.
The complete loop
How it works
- 1
Measure yourself
Height and inseam with the book method (we show you how), a 10-second toe-touch test, any aches you ride with.
- 2
Get ranges, not verdicts
Every dimension comes as a reference range with a starting recommendation and a “Why this result?” section with sources and limits.
- 3
Verify and ride
Set the bike up, confirm the camera result with a second independent recording, change ONE thing and re-check it after 2–3 rides.
Honest about the science. Because trust is the foundation of a fit.
The knee angle, not the myth
The classic “109% of inseam” formula misses the 25–35° reference window in 73% of riders (Peveler & Green 2011). That's why our primary method is the knee angle — formulas are starting estimates.
Ranges, not verdicts
A review of 16,578 studies (Husband 2024) found scientific consensus only for saddle height. Everything else we label plainly as convention with a direction — and we say so out loud.
Every number has a source
Expand “Why this result?” on any recommendation: you'll see the method, the modifiers applied to you, and citations graded by strength of evidence.
Audit the exact claim-to-source mapping, product use and limitations in our public evidence and methodology registry.
Frequently asked questions
Is OpenBikeFit really free?
Yes. The calculator and camera measurement are free to use in your browser, with no account, trial or hidden fee. OpenBikeFit is maintained by Balance IT to make an evidence-led bike-fit starting point broadly accessible.
What is the correct saddle height?
One that leaves your knee bent 25–35° at the bottom of the pedal stroke (the Holmes method). As a rough guide that's about 88.3% of your inseam measured from the bottom bracket to the top of the saddle — for an 84 cm inseam, around 742 mm. The calculator computes your exact range from your proportions, goal and flexibility.
How is this different from a studio bike fit?
A professional fit typically costs $150–400 (300–800 zł in Poland) and may be especially valuable for persistent pain, injury recovery and competitive racing. OpenBikeFit provides a free, evidence-led first pass: published reference ranges plus a live camera check of your knee angle. It cannot reproduce a fitter's physical assessment, and warning signs stop the recommendations.
Where do the recommendations come from?
From peer-reviewed literature: systematic reviews (Bini 2011, Husband 2024) and studies including Peveler 2008/2011, Martin & Spirduso 2001 and Holmes 1994. Every number in your result has a “Why this result?” section with citations, honestly labelled as science or fitter convention.
Is my data or video uploaded anywhere?
Your fit inputs, video and results are not uploaded: the MediaPipe pose engine runs on your device and fit records stay in your browser. The optional Help form is separate and sends only the feedback you deliberately submit. There is no account or ad tracking.
Does this replace a professional fitter or doctor?
No — it's an educational tool, not a medical device. For pain that doesn't improve after position changes, persists off the bike, wakes you at night or gets worse, we direct you to a physiotherapist or doctor. A built-in red-flag screen halts recommendations when something looks concerning.
Your bike can feel better today
Two measurements, two minutes. Research-backed ranges, a diagram of your bike, and a plan — free.
OpenBikeFit
Free, private bike fitting — a research-based calculator and a live camera measurement in your browser.
Educational guidance, not a medical diagnosis or a substitute for a qualified fitter. Stop and seek professional help when symptoms persist or worsen.