Originally Posted by
Pop N Wood
Not sure how a rim gets ready to bend into an S.
From improperly trained techs truing wheels by not caring what the spoke tension of a wheel feels like by just turning spokes till the wheel looks right. It leaves imbalanced tension that doesn't take much to warp a rim completely past a certain point. Can also happen with an improper wheel build, particularly in the rear, where the spoke tension is exceeding forces that the rim is meant to handle, usually someone new to building trying to get the non-drive side tension up to what they think is best. Any sudden change in tension, squeezing the drive side spokes or bumping them into something, will completely pretzel the rim before you know what's happened.