Isobars are mostly curved and the distance between them is rarely even. This prevents geostrophic winds from developing.
However, wind can still blow parallel to isobars. Besides the pressure gradient force and Coriolis force another force is needed for a balance. The centrifugal force balances these forces by pushing away from a high/low pressure center.

High pressure system
In a high pressure system everything goes vice versa. The pressure gradient force wants to go away from the center and the (strong) coriolis force pulls to the center. The centrifugal force pulls away from the center, balancing the forces and in order to create a wind blowing parallel to the isobars.

Coriolis is the force which develops because of the rotation of the earth. It makes global winds bow. See also: Coriolis force

Isobars are lines on weather maps which show pressure areas. See also: Isobars

A center where all the pressure around it is higher (in case of high pressure center) or lower (low pressure center) See also: Pressure centers

A force created by difference in pressure. This triggers the initial movement of air. See also: Pressure gradient

The centrifugal force pushes objects that rotate around a center away.

Coriolis is the force which develops because of the rotation of the earth. It makes global winds bow. See also: Coriolis force

Isobars are lines on weather maps which show pressure areas. See also: Isobars

A center where all the pressure around it is higher (in case of high pressure center) or lower (low pressure center) See also: Pressure centers

A force created by difference in pressure. This triggers the initial movement of air. See also: Pressure gradient

The centrifugal force pushes objects that rotate around a center away.