I've found that good steel rulers (old Staedtler in my case) have been easily accurate enough to measure spokes with; just place the hook over the end of the ruler (as long as the mm bits go right to the end) and it has always corresponded with the stated size.
YRMV
I've found that good steel rulers (old Staedtler in my case) have been easily accurate enough to measure spokes with; just place the hook over the end of the ruler (as long as the mm bits go right to the end) and it has always corresponded with the stated size.
YRMV