Skip to main content
Infinite Concept Universe
ICU/Bikes/Geometry Lab

BKU / LAB / GEARING

BIKES UNIVERSE

Machine · movement · culture · workshop · history · experiment

Explore Bikes Universe

BKU003 / GEOMETRY LAB

Change the references. Watch the geometry move.

This local educational model visualizes reach, stack, wheelbase, head-tube angle, fork offset and a simplified ground-trail relationship. It does not calculate fit, stability, agility, comfort, safety, suitability or a handling score.

Reference inputs
Horizontal BB-to-upper-steering reference.
Vertical BB-to-upper-steering reference.
Axle-center to axle-center reference.
Measured from the horizontal ground plane.
Offset term used by this simplified steering model.
Outside wheel+tire diameter for the educational trail model.
Definitions

Default reference state shown. JavaScript enhances the drawing but the assumptions and default values remain readable without it.

Bicycle geometry reference drawingTwo-panel default reference drawing. Frame references show reach 385 millimeters, stack 575 millimeters and wheelbase 1030 millimeters. Steering references show head angle 72 degrees, fork offset 45 millimeters, effective wheel diameter 700 millimeters and simplified ground trail 66.4 millimeters.FRAME REFERENCES · INDEPENDENT CHART DIMENSIONSREACH 385 mmSTACK 575 mmWHEELBASE 1030 mmSTEERING DETAIL · SIMPLIFIED TRAIL MODELHEAD 72.0°OFFSET 45 mmSIMPLIFIED TRAIL 66.4 mmEFFECTIVE Ø 700 mm
Reach reference385 mm
Stack reference575 mm
Wheelbase1030 mm
Simplified trail66.4 mm

ASSUMPTIONS

Visible before any conclusion.

The lab intentionally refuses to collapse geometry into a single ride label.

  • Two-dimensional side-view reference model on a level ground plane.
  • Reach and stack are drawn from a fixed bottom-bracket reference to an upper steering/head reference; they are not used to solve the full frame.
  • Wheelbase is axle-center to axle-center and is drawn independently from reach/stack.
  • Head angle is measured from the horizontal ground plane.
  • Fork offset is treated as the perpendicular offset term in the simplified trail relationship.
  • Effective wheel diameter is an educational wheel+tire outside-diameter input, not an ISO bead-seat diameter.
  • Simplified trail = (R × cos(head angle) − fork offset) / sin(head angle), where R is effective wheel radius.
  • The tool visualizes relationships only; it does not infer fit, stability, agility, comfort, safety, suitability or handling quality.

REFERENCE GRAPH

Open the definitions behind the controls.

Each control maps back to a stable BKU entity so the calculator never becomes detached from its definitions.

ReachStackWheelbaseHead angleMechanical trailWheel

Formula evidence is recorded in the source ledger as bku.evidence.mit-ocw.trail-formula. Evidence is not fetched at runtime.

ICU-EXPEDITION-025 / UNIT + FORMULA CONTRACT

Keep frame references, steering geometry and fit questions separate.

  • Reach, stack, wheelbase, fork offset and effective wheel diameter are normalized in millimeters; the enhanced result cards also show inch equivalents.
  • Head angle is measured in degrees from the horizontal ground plane.
  • The simplified trail calculation is transparent and linked to its evidence record; it is not a handling-quality model.
  • No result is an individualized fit, comfort, stability, agility, safety or suitability conclusion.

Review definitions · Save a research question

ICU / CONNECTED DISCOVERY

Continue through related ideas.

These are bounded editorial connections; paid placement does not influence them.

Loading public connections…

See reverse connections