Seat Tube Angle Calculator — Effective STA
Calculate the effective seat tube angle from saddle position.
From BB centre to saddle top
Horizontal distance behind BB
How We Calculate This
Effective Seat Tube Angle
Effective STA = 90 - atan(Saddle Setback / Saddle Height)
Setback is the horizontal distance the saddle is behind the bottom bracket centre. A greater setback means a slacker effective angle.
Frequently Asked Questions
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Last updated: 2025-02-20
All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.