foam core

TECHNOLOGY OVERVIEW:

The Partington R-Series PERFORMANCE and PERFORMANCE Ti wheelsets use a foam-core rim construction in place of a hollow carbon layup. The foam core serves two functions: it damps road-borne vibration, and it stabilizes the carbon fiber structure so the laminate can be tuned independently for stiffness and compliance.

VIBRATION ATTENUATION:

Foam has an inherent vibration-damping characteristic that a hollow carbon structure
does not. Embedding foam through the rim's cross-section reduces the transmission of high-frequency road vibration into the wheel, lowering rider fatigue and improving comfort over rough surfaces.

STRUCTURAL STABILIZATION & COMPLIANCE:

Beyond damping, the foam core supports the carbon laminate from the inside, preventing the local buckling that limits how thin or compliant a hollow carbon layup can be made. With that support in place, the laminate architecture can be tailored for increased radial compliance — improving comfort — without the stiffness or structural penalties that would come with softening an unsupported hollow structure.

PMI FOAM MATERIAL:

The core uses PMI (polymethacrylimide) foam, a rigid structural polymer foam. PMI foam is widely used in aerospace applications, including helicopter rotor blades, due to its high stiffness-to-weight and strength-to-weight ratios. When paired with carbon fiber composite, PMI foam produces a sandwich structure with specific stiffness (stiffness relative to weight) that exceeds what either material achieves alone.

MANUFACTURING PROCESS:

Partington has developed proprietary processes to manufacture this foam-core structure with high structural efficiency, high repeatability, and a refined surface finish. Each core is precision-machined before layup, producing a consistent substrate for the carbon laminate that is free of distortions, wrinkles, and other imperfections. This consistency allows carbon fiber to be applied more efficiently — using only the material needed for the required structural performance — resulting in a lighter, higher-performing wheel.

APPLICATION:

The practical effect is most noticeable on rough or broken road surfaces and over
long ride durations, where cumulative vibration is a primary driver of hand, arm, and upper-body fatigue. Because the compliance is engineered into the core-supported laminate rather than achieved by reducing wall thickness or stiffness elsewhere in the rim, the wheel maintains lateral stiffness and power transfer under load while still isolating the rider from high frequency road buzz.