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Installing Ceramic Hybrid bearings
Ceramic Hybrid bearings can provide performance benefits but to reap those benefits and attain good bearing life it is critical that they are properly installed.
Actually all the installation requirements of a ceramic hybrid are those that apply to any bearing but the nature of the hybrid means that it will fail more readily if these requirements aren't met. The strength of the ceramic ball (Si3N4 is approx 4 x the strength of steel) means that any misalignment or stress will damage the races at an accelerated rate causing premature faliure of the bearing.
The two major causes of failure of a ceramic hybrid (and these apply to all cartridge bearings) are:
These steps are general in nature but should provide a guide for most bearing installations
1. Check the new bearing first.
2. When removing the old bearing you will get a feel for how tight a fit it is. Suspension pivot bearings are often very tightly fitted where wheel bearings should be (but are not always) a looser press fit. Regardless of how the bearing is removed ensure that it comes out as straight as possible to keep the bearing seat in good condition. Removing a bearing almost always relies on pressure on the inner race which may 'bruise' the balls or races.
3. Clean the bearing seat. All grease, dirt , sealing and retaining compounds need to be removed from the bearings seat. You may need to use a dental pick or fine blade to remove some retaining compounds as used in BB cups. For wheels, if the original bearing was very tight to remove, use a coarse wet and dry to clean and smooth the seat. Finally use a very fine grit wet and dry to ensure the surface is smooth.
4. Once the bearing seat is clean use a very thin smear of light grease on the surface. Press the bearing into the seat using only the outer race for contact. As with removal ensure the bearing goes in as straight as possible. Ensure the bearing is fully seated.
5. Now that it is installed check the bearing for smoothness. If there is any roughness or catching that wasn't present before installation it would indicate that the bearing seat is too tight. This will almost certainly lead to premature failure so it is best to remove the bearing carefully and further prepare the seat, perhaps using a coarser wet and dry paper.
Deep groove cartridge bearings such as those used in most bicyles aplications are designed to run with no side load. They can and do accept brief side loads under normal operation, but what we are concerned about here is side loading caused by the set up and installation.
Some hubs etc the position of the bearing in the hub and on the axle is preset but others allow the user to set preload/side load. Examples of these are the Shimano external bearing BB's Mavic Ksyrium hubs.
In almost all cases there should be no preload set on the bearing. The aim is not allow side movement, that is the axle moving through the bearing, but in practise it is best to err towards side movement rather than sideloading the bearing.
The easiest way to check for side loading is to spin (the wheel or crank) and test as you are tightening the adjuster. As soon as you detect a reduction in spin, or feel any roughness, backup of the adjuster. If any side play is detected you may need to tighten more but it better to accept a little side play than to load the bearing. Often after a short running period this can be re-adjusted for a better result.
Regardless of the construction of the hub/bb check the spin of the bearings at each step especially when tightening any caps or adjusters. This allows you to identify and fix any problems now rather than after a bearing fails.