How do you calculate saddle height?

Multiply your inseam in centimetres by 0.883. That number is your saddle height in centimetres, measured from the centre of the bottom bracket to the top of the saddle. An inseam of 85 centimetres gives 75.1 centimetres. If your cranks are longer than 170 millimetres, subtract the difference; if shorter, add it.

How do you measure your inseam?

Without shoes, back against the wall, a book clamped firmly into the crotch with its spine against the wall, then measure from the top of the book to the floor. The book has to be pulled up harder than is comfortable: pulling too softly is the most common error and gives a saddle height one to two centimetres too low.

How many degrees should the knee be bent at the lowest pedal position?

Between 25 and 35 degrees, measured at bottom dead centre with the foot in the position you actually pedal in. That window is the criterion a bike fitter works to; the formula from your inseam is there to get you close quickly. If the leg almost straightens, the saddle is too high.

Where exactly is saddle height measured from?

From the centre of the bottom bracket, in a straight line along the seat post, to the top of the saddle at the point where you sit. Some tables measure from the pedal surface at its lowest point; those numbers sit roughly a crank length higher and are not interchangeable with these.

How many millimetres can you move the saddle at a time?

Three at most, and ride two sessions on it afterwards. Tendons and lower back adapt more slowly than the seat post, and anyone who moves a centimetre in one go cannot tell afterwards whether a complaint comes from the new height or from the speed of the change.

Does the LeMond formula hold for everyone?

No. It is a starting point that lands within about a centimetre for most riders, and that centimetre is exactly where the difference lives. Anyone with unusual thigh to shin proportions, thick soles or cleats set far back will be further out. The answer then lies with the knee angle and not with the sum.

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Saddle height calculator

Saddle height is the single setting that shapes your position on the bike most. This calculator gives you the starting point from your inseam, with the range you search in from there.

Inseam in cmCrank arm length in mmCurrent saddle height in mm (may be left empty)

Enter your inseam; the answer appears straight away. Nothing is stored or sent.

Measuring your inseam

1Stand with your back against a wall without shoes, feet about fifteen centimetres apart.
2Clamp a book or spirit level firmly into your crotch, spine against the wall, and pull it up until it feels like a saddle. Not gently: pulling too softly is the most common measuring error and gives a saddle one to two centimetres too low.
3Have someone measure from the top of the book to the floor, or mark it and measure it yourself.
4Measure twice. If the two differ by more than five millimetres, measure a third time and take the middle value.
5Then measure your current saddle height: from the centre of the bottom bracket, along the seat post, to the top of the saddle in the middle.

The trap

Moving the saddle straight to the answer in one go. Tendons and lower back adapt more slowly than a seat post does, and a saddle that goes up fifteen millimetres mostly feels wrong on the first ride. Move at most three millimetres at a time and ride two sessions on it before going further.

Why you get a range and not a number

The formula knows your inseam and your crank arm length, and nothing else. Your shoe sole, your cleat position, the stack of your pedal and the ratio of thigh to shin are not in it, and together those are worth about a centimetre. Within that centimetre the decision is not the arithmetic but your knee: at bottom dead centre there should still be 25 to 35 degrees of flexion. If the leg straightens out there, the saddle is too high, whatever the formula says.

How you notice it is too high or too low

Too high rarely feels wrong; you see it at the hips, which start rocking because you are reaching for the pedal, and you sit restlessly on the saddle. Tightness behind the knee and along the back of the thigh goes with it. Too low gives pressure at the front of the knee and the sense of pushing a heavy gear without being able to spin.

The crank arm length is in the sum

The factor 0.883 assumes cranks of around 170 millimetres. If you ride 175 you end up five millimetres further from the saddle at bottom dead centre, so the saddle goes down five millimetres; at 165 the other way round. The length is usually stamped on the back of the crank arm. It is also why the same saddle height on two bikes need not feel the same.

What a formula cannot see

How far forward or back your saddle sits changes the distance to the bottom bracket and therefore what the same height does. Pelvic tilt and bar height play their part too. A formula can tell you where to start; what actually happens while you pedal is only visible in the movement itself.

Common questions

How do you calculate saddle height?: Multiply your inseam in centimetres by 0.883. That number is your saddle height in centimetres, measured from the centre of the bottom bracket to the top of the saddle. An inseam of 85 centimetres gives 75.1 centimetres. If your cranks are longer than 170 millimetres, subtract the difference; if shorter, add it.
How do you measure your inseam?: Without shoes, back against the wall, a book clamped firmly into the crotch with its spine against the wall, then measure from the top of the book to the floor. The book has to be pulled up harder than is comfortable: pulling too softly is the most common error and gives a saddle height one to two centimetres too low.
How many degrees should the knee be bent at the lowest pedal position?: Between 25 and 35 degrees, measured at bottom dead centre with the foot in the position you actually pedal in. That window is the criterion a bike fitter works to; the formula from your inseam is there to get you close quickly. If the leg almost straightens, the saddle is too high.
Where exactly is saddle height measured from?: From the centre of the bottom bracket, in a straight line along the seat post, to the top of the saddle at the point where you sit. Some tables measure from the pedal surface at its lowest point; those numbers sit roughly a crank length higher and are not interchangeable with these.
How many millimetres can you move the saddle at a time?: Three at most, and ride two sessions on it afterwards. Tendons and lower back adapt more slowly than the seat post, and anyone who moves a centimetre in one go cannot tell afterwards whether a complaint comes from the new height or from the speed of the change.
Does the LeMond formula hold for everyone?: No. It is a starting point that lands within about a centimetre for most riders, and that centimetre is exactly where the difference lives. Anyone with unusual thigh to shin proportions, thick soles or cleats set far back will be further out. The answer then lies with the knee angle and not with the sum.

And the rest of your position?

Saddle height is one setting out of six. Knee and hip angle top and bottom, torso angle, elbow and the smoothness of your pedal stroke all come out of the same clip, per revolution and with the spread beside them.

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This is a position measurement for comfort, efficiency and performance. It is not a medical examination and says nothing about complaints or injuries.