Hip Angle at TDC

Why this matters

Hip closure at the top of the stroke governs comfort, breathing, and how aggressive the position is. A hip that closes too far at TDC can impinge at the front and restrict the diaphragm, especially with a big bar drop.

What good looks like

The torso and thigh close to ≈40°–50° at TDC and open smoothly through the stroke, with no pinch at the front of the hip and unrestricted breathing.

Common faults

• Very closed hip (< 40°) — aggressive drop plus limited hip mobility; can cause anterior impingement.
• Very open hip (> 50°) — upright, comfortable, less aero.

Coaching cues

• If the hip pinches at the top, raise the bars / reduce drop before touching the saddle.
• Pair with trunk angle — they together describe how aero vs. upright the fit is.

How to draw

1. Pause at top-dead-centre on the measured leg.
2. Torso line: acromion (shoulder) → greater trochanter (hip).
3. Thigh line: hip → knee.

Related measurements

• Knee Flexion at TDC — the knee side of the closed top position.
• Trunk Angle — overall aggressiveness of the posture.