Definitions first. Interaction second. No handling score.

Horizontal frame reference from the bottom-bracket center to a defined upper head-tube/steering-axis reference point under common geometry conventions.

Reporting conventions and exact reference points should be checked against the source geometry chart.

Vertical frame reference from the bottom-bracket center to a defined upper head-tube/steering-axis reference point under common geometry conventions.

Stack describes a frame reference; final hand position also depends on headset, spacers, stem and handlebar.

Distance between front and rear axle centers.

Wheelbase is one geometric quantity among many and should not be used alone to predict handling.

Angle used to describe the orientation of the head tube / steering axis relative to the ground plane under a stated convention.

Angle conventions and rounding vary; use the manufacturer or measurement method as the authority for a specific bicycle.

Angle describing the seat-tube axis relative to a ground/horizontal reference under a stated convention.

Effective and actual seat-tube angle may both appear in geometry charts and should not be treated as interchangeable.

Distance from bottom-bracket center to rear-axle center under a stated measurement convention.

Frame pivots, dropout geometry and reporting conventions can complicate comparisons.

Distance from bottom-bracket center to front-axle center.

Useful as a packaging/geometry dimension; it does not by itself determine ride behavior.

Vertical relationship between the wheel axle line and bottom-bracket center, commonly expressed as how far the bottom bracket sits below the axle line.

Not every chart reports this dimension, and wheel/tire choices affect ground clearance.

Vertical distance from the ground reference to bottom-bracket center for a stated wheel/tire setup.

Because the ground reference depends on wheel/tire dimensions, compare like with like.

Distance describing the front-axle center position relative to the steering-axis line under a stated convention.

The exact geometric convention should be documented when comparing sources.

Horizontal ground-plane distance between the steering-axis intersection with the ground and the tire contact-point reference in a simplified bicycle geometry model.

Trail is useful for geometric comparison but is not a complete handling prediction.

Ground-to-frame height measured at a stated point on or near the top tube.

Brands may use different measurement locations; compare the stated method.

Horizontal reference between seat-tube and head-tube/steering references intended to normalize sloping top-tube layouts.

Exact reference points vary by geometry chart; do not assume it equals physical top-tube length.