Bike Toolkit
Wheel math, gear ratios with live speed, standard wheel-builder spoke length, and drivetrain output torque — all in one place.
Outer diameter, circumference, rollout per revolution.
Inputs
Cyclo-computer rollout is typically a few percent less than the geometric circumference because of tire deformation. Enter a measured value if you want gear and torque tabs to use it.
Outputs
Outer diameter
686.0 mm
27.01″
Circumference (geometric)
2155 mm
2.155 m
Effective circumference
2155 mm
Geometric — override below if measured
Rollout / revolution
2155 mm
2.155 m
Revolutions per km
464.0
1 000 000 / C
Revolutions per mile
746.7
1 609 344 / C