Saddle height calculator

How to measure your inseam

• Stand barefoot with your back against a wall, feet about 15–20 cm apart.
• Pull a hardback book up between your legs, spine up, firmly, the way a saddle presses.
• Mark the top of the spine on the wall and measure from the floor to the mark.
• Measure two or three times and take the average. A centimetre off in your inseam is almost 9 mm off in saddle height.

How to measure saddle height on the bike

Measure from the centre of the bottom bracket (the axle the cranks turn on) along the seat tube to the top of the saddle, where you sit. If the saddle is higher or lower than the number above, change it in steps of 5 mm or less, not all at once.

A formula is only a starting point

The formula only knows your inseam. It doesn't know your crank length, the stack of your shoes and pedals, how your ankle moves as you pedal, or how flexible you are. Two riders with the same inseam can need different saddle heights.

The more reliable check is your knee angle at the bottom of the pedal stroke: most fitters aim for 143–153° (a fully straight leg is 180°). Below that the saddle is likely low, above it likely high. As a rough guide, 1° of knee angle is 2–3 mm of saddle height. See knee angle at the bottom of the pedal stroke for how to measure it and what to change.

Changing saddle height safely

• Mark where it is now. Tape on the seat post or a photo, so you can go back.
• Small steps. 5 mm or less at a time, one change at a time.
• Give it two or three rides before you judge a change.
• Moving the saddle back raises it too: 10 mm back adds about 3 mm of effective height.
• Tighten to the torque printed on the part, especially carbon seat posts. If unsure, ask a bike shop.