Raoul remarked, If you get a rim that was made using brand-new-fresh-dies , the clearances on the extrusion machines were tighter , the rim has thinner walls , the rim is lighter in weight . If you get a rim made using a tired-out-old-die , just before it was replaced , the clearances were larger , the rim has thicker walls , the rim is heavier in weight ( and surely stronger as well ) .
Then asked: How much difference can it possibly make ?
So I replied,
Quite a bit. Since I was in a fog earlier this morning, and couldn't recount the difference between a tubular and clincher rim....hopefully someone will find this tidbit of interest: I'm sure other bikeshop employees (or former ones) have done this too: When a good size rim order comes in to the shop, throw them on the digital scale, and see what a range is. I've done this lots of times. Works with tires too. The catalog weight for a Mavic Open Pro is 425 grams. I've weighed them and found a range from over 500grams, and I think the lightest ones I've weighed are about 430 grams, most are like 460g. That's about 10%! Since you need two to build a bike, and it's rotating weight, that's not insignifigant. Classic content: since at least the 70's, Mavic has been lying about rim weights in their catalogs...
Grant Toronto, I weigh my rims before lacing,Canada