• Parkinson's disease
• freezing of gait
• cycling
• motor control
• basal ganglia
• gait
• movement disorders

We recently described two patients with Parkinson's disease (PD) who presented with severe freezing of gait (FOG), but who also manifested a remarkably preserved ability to ride a bicycle.1 2 Following these publications, we have been approached by many patients who reported a similar discrepancy between severe gait difficulties and an often striking ability to ride their bicycle. Stimulated by these anecdotes, we carried out a semistructured interview with 53 consecutive outpatients with PD (diagnosed according to the UK Brain Bank Criteria). This interview was based on predefined questions about FOG, the ability to cycle and any subjective experience of ‘freezing’ during cycling (operationally defined as intermittent blockades of one or both legs during cycling). The precise question was ‘Have you ever experienced the feeling of being glued, or experienced freezing or blocks of the legs, while you were riding your bicycle?’ This question was asked by an interviewer with considerable experience with FOG, and more clarification was given if necessary. Also, when a subject answered positively, additional detailed questions were asked to confirm with more certainty that this was truly freezing. We excluded eight …