this is it

Look on the red sealed bit of that bearing - you might see the code for it

Or it is lasered into the outer metal ring. Just from looking at the pic I would assume it is 6004 (42 mm outer diameter, 20 mm axle, 12 mm wide).

Did you try to get the bearings out? I see no place for shaft seals. On my Honda rims there is place to install the shaft seals into the rim.

Most bearings used on Hondas are "standard" automotive/industrial bearings, which means that they come in standard sizes and are identified by standard bearing codes, e.g., 6004 (Honda pn 91054-MN8-741), 32006 (Honda pn 91016-KT8-005). This web page (http://www.vsource.org/VFR-RVF_files/BBearings.htm) concerns my VFR750FP, but you will find that the NC30 shares a lot of the same bearings and seals. Some bearings are Honda-only, so most bearing suppliers won't be able to help, but there are sometimes alternatives that can be used.

Ciao,

JZH

Want to thank you all for the great help.
This is the ral meaning of the forum.
Ciao
Pietro