This page now separates exact ideal eccentric-cam geometry from real bicycle-wheel securement. The connected animation moves the lever, eccentric cam and skewer together, while the worksheet deliberately removes the fabricated clamp-force curve and fixed rod-stress claim.
Ideal Circular-Eccentric Displacement
Explore the axial rise of a declared ideal circular eccentric and the chord traveled by its lever tip. This geometry does not calculate clamp force, preload, skewer stress, adjustment, compatibility or safety.
Equation Used
- The cam is represented by an ideal circle whose geometric centre is offset from its rotation axis by the declared eccentricity e.
- Theta is the declared rotation from the minimum-rise position and is limited to 0 through 180 degrees.
- The reaction face is ideal and remains tangent to the cam; axial rise is e(1-cos theta).
- The lever is rigid with declared pivot-to-tip length L; its tip chord from the start position is 2L sin(theta/2).
- The connected drawing is schematic and is not a dimensioned commercial skewer.
- Cam profile, over-centre retention, preload, thread adjustment, friction, elasticity, tolerances, skewer diameter, stress, clamp force, fatigue, compatibility, installation, inspection and safe operation are excluded.
Replaces the invented clamp-force curve and fixed rod-stress calculation with exact ideal eccentric displacement and explicitly excludes real securement and safety assessment.
An eccentric cam converts lever rotation into axial skewer travel
US Patent 4,033,627 describes a bicycle-wheel quick release with a threaded skewer end, cup-shaped clamping head and circular eccentric cam that produces relative longitudinal motion. EP0508436B1 likewise describes an eccentric cam rotated by a hand lever between released and clamped positions.
The animation preserves that connection: lever and eccentric rotate together, the cam bears on a reaction cup, and the skewer translates axially.
Use this only as an ideal geometry demonstration
The worksheet calculates displacement for a declared circular eccentric and lever length.
It cannot determine whether any wheel, hub, frame, clamp or skewer is correctly adjusted, compatible or secure.
Ideal circular-eccentric rise
No force follows from these equations without the real cam profile, preload, compliance and friction.
A transparent ideal example
For theta=180 degrees, e=0.50 mm and L=65 mm, ideal rise is 1.000 mm, full throw is 1.000 mm, remaining travel is zero and the lever-tip chord is 130.00 mm.
Displacement is not clamping performance
A real quick release depends on cam profile, over-centre geometry, nut adjustment, skewer stiffness, friction, interfaces, dimensions, materials and condition. Manufacturer instructions govern inspection and use.
The former Gaussian force bump, arbitrary clamp range, fixed 5 mm rod stress, installation claims and safety conclusions are removed.
Quick-release geometry questions
Does 1 mm of rise imply a particular clamp force?
No.
Does 180 degrees prove the lever is safely closed?
No.
Does the calculator assess skewer stress?
No.
Can this replace the product manual?
No.
Quick-release cam references
- US Patent 4,033,627: bicycle skewer, reaction member, clamping head and circular eccentric cam producing longitudinal motion.
- European Patent EP0508436B1: eccentric cam with bearing bore and hand lever moving between clamped and released positions.
- Shimano Quick Release User Manual: internal-cam topology and device-specific adjustment, closure and inspection context.
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