Originally Posted by
maartendc
Could I reuse the spokes if the ERD of the old rim is 598mm and the new one is 602mm? Can I account for that 4mm variation you think?
There is some room for judgement/preference/fudging WRT spoke length, so it depends on where your current spokes ends in the nipples.
If your current build is kinda long, then 2 mm shorter can be OK.
If your current build is mid-range, then 2 mm short will leave a questionable build.
If your current build is kinda short, then 2 mm short will leave an outright poor build.
Unless you tinker around with longer nipples, a method usually frowned upon.