Calculate bike seat height from cycling inseam using the LeMond or 109% method, with metric and imperial results and clear measurement reference points.
Bike Seat Height Formula
The calculator uses the LeMond method as the primary output, with a 109% cross-check.
- Inseam: cycling inseam, floor to crotch, in cm
- Crank Length: from spindle center to pedal axle, in cm (mm ÷ 10)
- Saddle Height: measured along the seat tube from the center of the bottom bracket to the top of the saddle
If you only have rider height, the calculator estimates inseam as Height × leg ratio (44%, 46%, or 48%). A measured inseam is always more accurate. Use the resulting number as a starting point, then fine-tune by feel over a few rides.
Reference Tables
Quick starting points by rider height, assuming an average 46% leg proportion and the LeMond 0.883 multiplier.
| Rider Height | Est. Inseam | Saddle Height (BB to saddle top) |
|---|---|---|
| 160 cm / 5’3″ | 73.6 cm | 65.0 cm / 25.6 in |
| 170 cm / 5’7″ | 78.2 cm | 69.0 cm / 27.2 in |
| 175 cm / 5’9″ | 80.5 cm | 71.1 cm / 28.0 in |
| 180 cm / 5’11” | 82.8 cm | 73.1 cm / 28.8 in |
| 185 cm / 6’1″ | 85.1 cm | 75.1 cm / 29.6 in |
| 190 cm / 6’3″ | 87.4 cm | 77.2 cm / 30.4 in |
How to read the result and adjust from there:
| Symptom | Likely Cause | Adjustment |
|---|---|---|
| Hips rocking on saddle | Saddle too high | Lower 3-5 mm |
| Pain behind the knee | Saddle too high | Lower 3-5 mm |
| Pain in front of knee | Saddle too low | Raise 3-5 mm |
| Quads burn out fast | Saddle too low | Raise 3-5 mm |
| Reaching toes at bottom | Saddle too high | Lower 5+ mm |
Example and FAQ
Example. Inseam 82 cm, 172.5 mm cranks. LeMond gives 82 × 0.883 = 72.4 cm from the bottom bracket to the top of the saddle. The 109% check gives 82 × 1.09 = 89.4 cm pedal axle to saddle, minus 17.25 cm crank = 72.1 cm. The two methods agree within 3 mm, so 72.4 cm is a reliable starting height.
How do I measure cycling inseam? Stand barefoot against a wall with feet about 15 cm apart. Place a hardcover book spine-up between your legs and pull it firmly into your crotch to mimic saddle pressure. Measure from the floor to the top of the spine.
Does crank length matter? It does not change the LeMond saddle height (BB to saddle top), but it does change the 109% pedal-to-saddle distance. Longer cranks mean the foot drops farther at the bottom of the stroke, so adjust if you swap cranks.
How is this measured on the bike? Run a tape from the center of the bottom bracket along the seat tube to the top of the saddle, where your sit bones rest.
Is this for road or mountain bikes? The formula works for both. Mountain riders often run 5-10 mm lower for control on technical terrain.
