Using an exercise bike desk can potentially improve productivity by integrating physical activity into a traditionally sedentary work environment. Physical activity is known to enhance cognitive function, increase energy levels, and improve mood, all of which can contribute to better work performance. The movement involved in cycling can increase blood flow to the brain, which may enhance concentration, memory, and creativity. 
Moreover, exercise releases endorphins, which can reduce stress and improve overall mental well-being, leading to a more positive work attitude and increased motivation. The ability to switch between sitting and cycling can also help prevent the physical discomfort associated with prolonged sitting, such as back pain and stiffness, which can be distracting and reduce productivity.
However, the impact on productivity can vary depending on the individual and the nature of their work. Some people may find the dual task of cycling and working distracting, especially if their tasks require intense focus or fine motor skills. Others may benefit from the rhythmic movement, finding it helps them maintain a steady work pace.
Additionally, the type of work being performed can influence the effectiveness of an exercise bike desk. Tasks that require deep concentration or complex problem-solving might be better suited to a traditional desk setup, while more routine or creative tasks might benefit from the added physical activity.
In conclusion, while an exercise bike desk can offer health benefits and potentially enhance productivity for some individuals, its effectiveness will depend on personal preferences, work tasks, and the ability to balance physical activity with work demands.