How knee and elbow angles are calculated
Which measurements go in, how the law of cosines turns them into knee and elbow angles, and what the result does not show.
What goes in
Enter limb lengths, bar and peg positions, and torso lean. The law of cosines turns a triangle's three sides into its angles. A limb too short shows unreachable.
Read the assumptions
The drawing shows geometry only: no comfort score, no fit rating. Lean is your choice, not a measured posture.
Compare before and after
Enter your own measurements or restore a saved plan file. Pin a baseline before changing an input, then compare the result. Export a copy with the assumptions intact. Example styles are not manufacturer specifications.
A worked example
Standard style, default rider. Pegs sit 180 mm forward and 500 mm below the hip: 531.4 mm away. A 429 mm thigh and 499 mm shin give a knee of 69.4°. Grips sit 690 mm forward and 300 mm above the hip. A 504 mm torso leaning 15° makes shoulder to grip 589.9 mm. A 285 mm upper arm and 345 mm forearm give an elbow of 138.7°.