A shock absorber for a bicycle or another, at least partly muscle-powered, vehicle has a damper device with a damper housing in which a first and a second damper chamber are separated from one another via at least one damper piston. A piston rod connected with the damper piston extends from the damper piston through the second damper chamber out of the damper housing. The first damper chamber is in communication with the second damper chamber via a flow duct that leads through the piston rod out of the damper housing toward at least one throttling device. The flow duct, at the throttling device, has a damping duct provided with a field-sensitive rheological fluid which, by way of a field generating device disposed at the throttling device, can be exposed to a field of a predetermined strength to influence the pass-through flow of the field-sensitive rheological fluid through the throttling device.