Enter the reach and stem angle into the calculator to determine the bike stem length. This calculator can also evaluate any of the variables given the others are known.

Bike Stem Formula

The following formula is used to calculate the length of a bike stem.

BSL = (R * cos(A)) + (H / sin(A))


  • BSL is the bike stem length R is the reach (the horizontal distance from the center of the bottom bracket to the top of the head tube) A is the angle of the stem H is the height difference between the saddle and the handlebars

To calculate the bike stem length, multiply the reach by the cosine of the stem angle, then add the result to the height difference divided by the sine of the stem angle.

What is a Bike Stem?

A bike stem is a crucial component of a bicycle that connects the handlebars to the steerer tube of the bicycle fork. It essentially serves as the conduit for steering control, allowing the rider to maneuver the bike. The length and angle of the stem can significantly affect the bike’s handling and the rider’s comfort and performance.

How to Calculate Bike Stem?

The following steps outline how to calculate the Bike Stem Length (BSL) using the given formula:

  1. First, determine the value of R (reach) in meters.
  2. Next, determine the value of A (angle of the stem) in radians.
  3. Next, determine the value of H (height difference) in meters.
  4. Using the formula BSL = (R * cos(A)) + (H / sin(A)), substitute the values of R, A, and H into the formula.
  5. Finally, calculate the Bike Stem Length (BSL) using the formula.

Example Problem:

Use the following variables as an example problem to test your knowledge:

R (reach) = 0.5 meters

A (angle of the stem) = 30 degrees

H (height difference) = 0.2 meters