This work investigates bicycle drivetrain efficiency, with a focus on the understanding and optimization of paraffin wax-based chain lubricants. To enable robust analysis, a custom-built, high-precision testing rig and a novel in-situ chain wear measurement device were developed, allowing for systematic, long-term evaluation of chain and lubricant combinations under realistic cycling loads. These experiments were complemented by comprehensive material characterization, including calorimetric, rheological, hardness, and mass-spec analyses, to correlate wax chemistry and physical properties with drivetrain performance.

 

Results showed that paraffin wax lubricants with melting points between 60–70°C and higher molecular weight offer the optimal balance of drivetrain efficiency and lubricant longevity, outperforming waxes of low-melting that were soft and easily displaced, and high-melting that were brittle and flaky. Lubricants with lower molecular weight or microcrystalline structures gave rise to rapid wear and significant efficiency loss. These findings provide valuable criteria for wax selection and formulation for both high-performance and everyday cycling applications.

 

A novel Dowd-Cavanaugh-Mansson (DCM) model was introduced, integrating cadence and torque into a single linear predictor for drivetrain efficiency across a broad range of operating conditions. This model enables accurate prediction of drivetrain losses under scenarios not directly tested.

 

Beyond lubricant selection, experimental results demonstrated that drivetrain efficiency decreases approximately linearly with increasing gear ratio, producing up to a 2% change in overall efficiency across typical cycling configurations. By integrating the precision testing rig with lubricant material analysis, this work addresses key knowledge gaps and offers actionable guidance for cyclists, manufacturers, and sports engineers aiming to maximize drivetrain efficiency and longevity.