Calculate your ideal crank length using three formulas: the Machine Method, Lennard Zinn, and Graeme Obree. Works for road, gravel, MTB, and TT/triathlon bikes with any crankset, including Shimano and SRAM.
Slide or type your measurements. Both cm and in are editable.
Your measurements suggest a longer crank, but 180 mm is the longest size widely available. Consider a custom crankset if needed.
Save your results and get the saddle height guide
Changing crank length means adjusting your saddle. I'll send you your personalised crank length results, the exact saddle height adjustment formula, and how to test the switch without committing.
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Please remember that this calculator provides estimates and should only be used as a general guide.
I recommend seeing a professional bike fitter to discuss the best crank length.
How to Measure Inseam Length?
To measure your inseam length, follow these 5 simple steps or watch the video below:
- Prepare a 0.75 to 1-inch (1.9-2.5cm) thick book and a tape measure.
- Take off your shoes and stand with your back to the wall.
- Place the book between your legs (in your inseam), pull it up firmly, and hold it in place with your legs. Make sure the book is pressed firmly against the wall.
- Measure the length from the top of the book to the floor.
- Take the measurement.
NOTE: The inseam for choosing the right bike size is different (a few inches longer) from the inseam used to choose the pants’ size. Remember that inaccurate inseam length may affect the recommended bike size.