Bends on classic drops are like sections cut out of a circle - they have a constant radius.

On modern "new ergo" type of bars, the initial top part of the drop has quite tight bend to facilitate positioning of the hoods. The lower part of the drop bend is much wider to enable smooth transition between various hand positions in the drop. In technical terms, the initial radius of the drop is smaller, and it then increases toward the end of the bar - thus Variable Radius Drop.