Even so, the data transfer rate, the time it takes to read or write one full sector, is small compared to the time it takes to get to the right sector, which breaks into two parts:

1. seek delay -- the time it takes the stepper motor to move the read-write head to the right track
2. rotational delay -- the time it takes for the platter to spin around so that the start of the sector comes under the head

The larger the platter is, the longer the rotational delay because the tracks are longer. Another anomaly is that the bit density is greater towards the center than at the rim because of the differences in lateral (sideways) velocity when the angular velocity (rate of rotation) is held constant. Modern disk drives compensate for this in various complicated ways.