Originally Posted by
cny-bikeman
Even a 2.5mm difference from round (assuming the high and low are equally far off) is too much for a fairly evenly tensioned wheel. I would consider that rim to be defective.
I would agree with you if the rim started out that way before lacing the spokes. But a hop or dip of 2.5 mm once the lacing has been done and the preliminary tension applied could easily just be due to errors made in the early part of the process that will be ironed out as the truing and tensioning continues. It is not necessarily due to an initial defect in the rim. The real way to tell is how easily the wheel comes to final true and balanced tension. If it all smooths out easily, then there wasn't much wrong with the rim to begin with. The most troubling rim defects are the ones that need big spikes in tension to pull into shape like you sometimes have at the joint/seam.