Thanks all
First of all, thank you Piedmontbuckeye for talking like "Jiminy Cricket" and YES I DO need to get my micrometer out and do some measuring.
Pity the bike is in Italy and this Ural wheel is in Russia...
Badwolf, THANK YOU for explaining the bearing idea, I had NOT thought about this one !!!
Dave, ABZZ-olutely right !
BUT...
...a bike mechanic expert at lacing wire wheels ?
You mean like pink elephants and that thing about being rarer than hens' teeth ?
Unfortunately... many mechanics don't even know how to setup points&condenser ignition, never mind lacing spokes...