BKU / MECHANISMS

Trace force, motion and control through the machine.

Mechanism records give Workshop a reusable middle layer between a visible symptom and a service procedure. BKU002 describes transfer paths; it does not diagnose a specific bicycle from generic text.

MECHANISM

Chain drive

INPUT

pedal torque at chainring

TRANSFER

chainring teeth engage chain → chain carries tension → rear sprocket receives chain force

OUTPUT

rear sprocket / rear wheel drive

Open mechanism →

MECHANISM

Derailleur shifting

INPUT

rider shift command

TRANSFER

control moves derailleur position → chain is guided laterally → chain engages a different sprocket/chainring

OUTPUT

selected transmission ratio

Open mechanism →

MECHANISM

Fixed-gear drive

INPUT

crank and rear-wheel rotation

TRANSFER

rear sprocket is rotationally coupled to hub without a coasting freewheel in the drive path

OUTPUT

crank rotation remains coupled to driven wheel rotation

Graph record

MECHANISM

Freewheel / freehub coasting

INPUT

rear wheel overruns drivetrain speed

TRANSFER

one-way clutch or ratchet architecture permits wheel rotation without forcing chainring rotation

OUTPUT

coasting while wheel continues turning

Graph record

MECHANISM

Rim braking

INPUT

rider brake input

TRANSFER

brake transmission moves caliper/pads → pads contact rim braking surface → friction produces opposing torque

OUTPUT

wheel deceleration

Graph record

MECHANISM

Disc braking

INPUT

rider brake input

TRANSFER

brake transmission moves caliper pistons/pads → pads clamp a rotor → friction produces opposing torque at hub

OUTPUT

wheel deceleration

Open mechanism →

MECHANISM

Steering rotation

INPUT

rider steering input

TRANSFER

handlebar/stem turn steerer → headset bearings permit rotation → fork reorients front wheel assembly

OUTPUT

front-wheel steering angle

Graph record

MECHANISM

Pneumatic tire support

INPUT

inflation pressure plus tire/casing structure

TRANSFER

contained air and casing support load → tire deforms at contact patch

OUTPUT

load support and compliant ground contact

Graph record

MECHANISM

Suspension spring + damping

INPUT

wheel/frame relative motion

TRANSFER

spring stores/returns energy → damper dissipates motion energy through controlled resistance

OUTPUT

managed suspension motion

Graph record

Workshop / Interface Explorer Interface verification library

ICU / CONNECTED DISCOVERY

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ICU companion

Compare the same motion patterns outside the bicycle.

Use the Motion, Mechanism and Kinetics Explorer to manipulate 18 idealized gears, cams, levers, linkages and motion-transfer models. It is conceptual kinematics, not bicycle diagnosis.