How to Measure Your Inseam for Bike Fit

• A wall and a hard, flat floor (not carpet if you can avoid it)
• A hardback book or a carpenter’s level with a straight edge
• A pencil and a tape measure
• A helper makes it easier, but you can do it alone

1. Take your shoes off. Wear thin, close-fitting shorts or cycling shorts without a thick pad.
2. Stand with your back against the wall, feet flat and about 15–20 cm (6–8 in) apart — roughly the width your feet are apart on the pedals.
3. Hold the book upright between your legs with its spine up, and pull it firmly up into your crotch. The pressure should be similar to sitting on a saddle: firm, not painful.
4. Keep the book level and its spine against the wall. A small level on top of the book, or a helper watching from the side, helps.
5. Mark the wall at the top edge of the spine, step away and measure from the floor to the mark.
6. Repeat two or three times and use the average. Results within 5 mm of each other are good.

• Measuring with shoes on — adds the sole thickness and inflates every result based on it.
• Too little upward pressure — the most common error; it makes the inseam (and the saddle) too low.
• Tilted book — if the book slopes, the mark on the wall is wrong. Keep the spine horizontal.
• Using trouser inseam — clothing sizes are measured differently and are usually several centimetres shorter.
• Feet too wide or together — standing in a wide stance shortens the measurement; stand as you would over the pedals.

FitInspector can pre-fill your measurements from a standing photo taken next to your bike, using the bike’s wheel as a size reference. It is convenient, but be aware of what it measures: the photo estimate is a hip-to-floor leg length, not the pubic-bone measurement bike fitters traditionally use.

• Calculate your saddle height: inseam × 0.883, then adjust for discipline and crank length — see the saddle height guide.
• Check a frame size chart that uses inseam as well as height — see the road bike size chart or the full bike size guide.
• Or enter height and inseam in the bike fit calculator to get saddle height, handlebar width and a frame size suggestion in one go.