... 25x52x20.6 ... 25x47x12 ...
If you search for "bearing 25x52x20.6" and "bearing 25x47x12" you'll find these are standard off-the-shelf bearings available at your local supply house ... or am I missing something?
Sorry it has been so long,
And yes, You are indeed missing something. Took the time to do the research and to educate myself and this is some of what I found.
The Bearings for my bike are of a "deep groove" roller or double roller type(Depending on which bearing). The part numbers are:
3205-2RS for the 25x52x20.20.6 bearing
and
6005 RSR for the 25x47x12 bearing.
The smaller one (6005 RSR) is easy to find just about anywhere on the net. The larder one (3205-2RS) I found for $30-ish dollars each on Amazon. Was extra lucky in that they are INA's which is the modern name of the OEM.
Now back to details. When ordering bearings for you "must" make sure that they have the RS code which means that they are sealed/sealed roller bearings. A Z or ZZ code means that there is a metal shield for the bearings but this shield does not seal/ keep the grease in or dirt out.
Last note is to remind again that you want a "deep groove" roller or double roller type. When you type in the bearing dimensions you will get every conceivable variation for this size bearing.
Basically, use the part number off of the bearing to avoid headaches, trying to order by size makes you have to go through all of the engineering choices that the designers made i.e. ..."tapered" or "angular contact" or "flat" or "roller' or "double roller" and does it need to be deep grooved and or sealed?
I was making thing way to hard on myself by searching by size. Searching by part number made thing easy and rescued me from a labyrinth of decisions.
Later,
Freelancer