The latest NML Enduo™ Evolve has been carefully designed and tested to ensure high efficiency power transmission and set a new standard for cycling drivetrains. This article presents the efficiency of Evolve sprockets as compared to standard Shimano CS-R8000 roller chain sprockets using a Shimano Dura Ace CN-HG901 - 11 speed chain. This efficiency testing was conducted by the National Physics Laboratory (NPL), an independent laboratory based in the UK. The test methodology and chain preparation process are described and the averaged results are shown and discussed.
Two identical sprockets were set up at the input and output shafts of the NPL test rig as shown in the diagram below. The sprockets were laterally aligned and the centre distance set to allow some slack in the chain; this centre distance was kept constant throughout all of the tests. Each test took approximately 5 minutes. The time intervals between tests were identical to make sure that any effects of temperature change from test to test were comparable in all cases.
Chain / sprocket setup
Two identical Shimano Dura Ace CN-HG901 - 11 speed chains were lubricated and “run-in” (see section 2.2) prior to testing to maximise their potential performance. Each chain was then tested on each sprocket setup in turn.
In order to determine whether the running duration of the chain on the NPL rig had any effect on the results, the second set of tests on the second chain were performed in the reverse order.
All the efficiency tests were carried out at a constant rotational speed of 480 rpm.
<aside> 💡 As typical track cyclists ride with a cadence between 100 and 120 rpm and a gear ratio between 4 and 5, the 480 rpm test speed sits comfortably within this typical range.
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For each test, the relationship between the applied power and the drive efficiency (measured as output torque / input torque, expressed as a percentage value) was determined by varying the braking torque over the power range of interest (300 W to 900 W).
The following procedure was followed to run in the chains for optimal performance: