What We Test For and Why
Testing for the Correct Conditions
We have found that standard bearing industry testing for ball bearings does not necessarily relate to bicycle applications. Most bearing industry testing for the smaller radial bearings used in bicycles are performed at very high RPM (over 5,000-10,000 RPM), and with only light loads applied in a radial direction. In contrast, bicycle hub bearings spin at just 200-300 RPM and bottom bracket bearings rarely exceed 120 RPM in most situations, and both with much higher radial and axial loads. For this reason Enduro designed and built a custom test machine which more closely replicates the conditions of load forces and speeds of bicycle bearings. The first machine we built almost 20 years ago, and we are currently building the latest generation which will be running later this year giving us more information to improve our designs.
Using comparative analysis against many well known brands and lesser known brands, we have been able to develop testing parameters and minimum expectation benchmarks to determine what is an acceptable bearing. And to determine what is a better bearing, and what is the best bearing.
A recent example of our testing process and results is shown below for the 6902 bearing size. For this particular testing cycle, we included over 20 brands and types, but are showing only the top 4 bearings tested below. The testing parameters were as follows for this particular run: 160 lbs. of radial force applied, 65 lbs. of thrust force applied to the outer race against inner race, 120 RPM for 20 hours. Ambient temperature 68º F. Bearing pressed into a 6061 aluminum “typical” section of hub.
The average measurement across of actual galling pits after testing are as follows:
Enduro XD-15: 0.04 mm
Enduro Zero: 0.09 mm (x2 larger galling pit size)
Famous Competitor: 0.2 mm (x5 larger galling pit size)
Famous Competitor Coated: 0.3 mm (x8 larger galling pit size)
The Image to the right shows the inner race of the competitor’s bearing after the 20 hours of continuous testing. Even after just 20 hours of running you can see pits starting to form that are in excess of 0.2mm depth.
The Image to the right shows the inner race of an Enduro XD-15 bearing after the 20 hours of continuous testing. When compared to the competition, there is almost no discernible wear on the XD-15 inner race at all and there is still a mirror finish on the groove
(Note the width and depth of the Enduro XD-15 bearing groove is also considerably deeper and wider)