The whole process is beginning to sound a little tricky and I'm thinking only a person very qualified in replacing the bearings should be doing the job.
Is there any difference replacing the entire kit using HB-HY100 or just replacing the bearings using HB-HY123?
Is the process any easier or less tricky if only HB-HY123 is replaced?
As said before, the only part of the upgrade that seems impossible (to me at least) to carry out yourself is to replace the cups from the Bora Ultra hubs with the Cronitect ones.
The rest is very straightforward and in no way different from replacing steel bearings in other cup and cone bearing wheels.
Other than that all you need are two M5 Allen keys to remove the axles, one 2M5 Allen key to remove the bearing adjustment nuts.
Replacing just the steel bearings with ceramics would bring the wheels up to current USB level (as per Hyperon Ultra from a few years ago) and you could just as well use either HB-HY023 or the newer HB-HY123 kit.
HB-HY123 is said to have a superior quality retainer, in casu PEEK instead of the phenolic material used even for the HB-HY023 kit.
The ceramic balls of the HB-HY123 kit are also reportedly higher grade.
If anyone could confirm this?
The next step up would be to replace the current cones for the Cronitect ones which are hardened to the point that they approach the hardness of ceramic.
But after all this you're still stuck with the current cups which need special tooling to replace and someone willing to work on your wheels.
So the Cronitect cups as per HB-HY100 kit are useless to us and your bearings will be rolling on a very hard cone on one end whilst on the other it will be riding against a cone that's said to be ceramic ready but not nearly as hard a surface as the Cronitect treated ones.
My point being is that if you intend to keep the Bora Ultras and want to upgrade them to CULT level yourself it's pretty much impossible.
If, however, you want to upgrade them to USB level it's very easy as all it takes is either 4 HB-HY023 (cheapest) or 4 HB-HY123.
In the latter case I'd think it's wise to use special ceramic bearing grease (Dupont de Nemours Krytox 200 or similar) instead of oil.
Or use oil for all bearings except for the one at the driveside as it's invariably that bearing that takes the bulk of the torque transfer, it's also the most exposed to contaminants.
If using oil you'll inevitably will have to check the bearings on a regular basis as it just won't stay put as grease would do.
As for the asking price of the HB-HY123 kit, I wouldn't know.
There's just not enough on the net yet to start comparing.