Summary of Results

• 19 models of derailleur pulleys were tested for efficiency.  All models were tested as a set of two pulleys (typically one upper, and one lower pulley).  Based on the data, the CeramicSpeed pulley is the most efficient pulley, consuming 0.033 watts/set.  The results showed the Shimano Acera as the least efficient pulley of the group, consuming 1.370 watts/set.
• The difference between the most efficient and least efficient set of pulleys is 1.337 watts.
• Of the three bearing technologies (Ceramic BBs, Steel BBs, and Sleeve Bushings) Ceramic BBs consumed an average of 0.056 watts/pulley.  Steel BBs consumed an average of 0.069 watts/pulley. Sleeve bushings consumed an average of 0.577 watts/pulley.

FRICITION FACTS EFFICIENCY STANDARD- PULLEY ENERGY CONSUMPTION

Graph 1: Efficiency results of 19 models of pulleys, per pulley set.

PULLEY BEARING TECHNOLOGIES- AVERAGE EFFICIENCIES

Graph 2: Average Efficiencies for Ceramic BB, Steel BB, and Sleeve Bushings, per pulley.

Complete Results 

Table 1: Individual Results and Bearing Technologies by Pulley Model

Test Details

The goal of the test was to determine the most efficient set of derailleur pulleys, and to compare efficiencies of common bearing technologies used within the pulleys. For the test procedure, the pulleys were subjected to a similar load and RPM as in a true bicycle drivetrain.  In order to provide a broad comparison of products and technologies, pulleys were selected that ranged from high to low price, with ball bearing and bushing technologies.  Pulley models were purchased through typical on-line bicycle retailers, and each model was purchased as a set of two pulleys; top and bottom. 

This test was performed to rate pulley efficiency on two different aspects.  Firstly, this test compares the efficiencies of multiple models of pulleys on an absolute scale, compared to each other, regardless of bearing technology used. Secondly, this test examines the efficiencies of three unique load bearing technologies; the ceramic BB, the steel BB, and the sleeve bushing (steel, plastic, and ceramic bushings all combined).

Test Method

This test used the Friction Facts Reactive Torque Pulley Test Method (RTPT).

• All pulleys were tested at 458 RPM.An 11T pulley would turn at this rate with a 53T front /11T rear gear combination at 95RPM cadence.
• All pulleys were loaded with a 4.5lb weighted wheel.This load is the approximate force to which the pulley is subjected by the tension in the chain spans (by the derailleur tensioning spring).
• The accuracy of the RTPT is +/- 0.001 watts.
• Each pulley was run for a minimum of 10 minutes on the test apparatus prior to the data capture. Data was captured at the end of each sample’s test run.
• Data was averaged at 1-minute intervals.Sampling rate was 25 samples/second.

Side note

As seen in the results page, often the lower and upper pulleys of a model tested relatively close to each other with regard to efficiency .  However, three specific models exhibited a substantial difference in efficiency when comparing the upper and lower pulley measurements.  These three models are the Shimano Dura Ace, Shimano Ultegra, and Campagnolo Super Record.  This variation is due to the manufacturer using dissimilar bearing technologies for upper and lower pulleys.

• The Campagnolo Super Record uses a ceramic BB in the lower pulley, and a metal-metal bushing in the upper pulley.The Campagnolo ceramic BB lower pulley tested very efficient (it is the second most efficient pulley, when looking at pulleys individually).  However, the upper bushing tested at a much lower efficiency, causing thetotal efficiency of the set to rate in the lower-third of all pulleys tested.
• The Shimano Dura-Ace uses steel BBs in both lower and upper pulleys.  The lower pulley uses a single row bearing.  However, the upper pulley uses a two-row bearing system, with relatively small balls when compared to the other bearings found in the pulleys in this test.  This two-row system used in the upper bearing tests at a lower efficiency than the single-row bearing in the lower pulley.
• The Shimano Ultegra uses a steel BB in the lower pulley and a ceramic bushing for the upper pulley.

Final note- This test was performed in clean laboratory conditions.  The test procedures do not take into account the effects of environmental variables on efficiency, such as road dirt, water, etc.  Many pulleys are designed to accommodate multiple facets of operational performance, not only efficiency.  Please keep this in mind, as this test solely looks at clean conditions efficiency