Originally Posted by
urbanknight
..only reuse the spokes if you're using .. EXACT same ERD.
There's some leeway in ERD, an exact match isn't required and is mostly a question of build aestethics. But first one needs to know how the current wheel looks - are spokes flush with nipples, protruding a little, or already a little submerged?
If they're already protruding then going to a smaller ERD is a definite no-no, as that would bring a high risk of spokes bottoming out on the threads before reaching full tension.
But if current spokes are sitting flush there's no functional objections against using a rim with something like 5 mm bigger ERD.
Some adjustments can also be made by going to longer nipples, just make sure that the offset in ERD is big enough to keep the longer nipples from bottoming out.
Supposedly a little more risky would be to re-lace the wheel for a different cross.
For a hub with average flange height dropping/adding one cross would change the required spoke length with about 10 mm.
Established lore regarding hub re-use recommends that no of crosses and spoke orientation(inbound/outbound) should be maintained to prevent undue strain on the hub flanges - sounds reasonable, but then hub flange failures aren't particularly common.