Shock absorber and method for operating a shock absorber for a bicycle wherein a relative motion of a first and a second component interconnected via a damper device is dampened. The damper device includes a controllable damping valve having at least one field generating device with which a field-sensitive medium can be influenced by applying a field intensity of the field generating device. A parameter for the current speeds of the first and second components relative to one another is obtained in real time. For damping, a current field intensity to be set is derived in real time by way of the parameter from a characteristic damper curve and by the field generating device the field intensity to be currently set is generated in real time for setting in real time a damping force which results from the predetermined characteristic damper curve at the parameter obtained.