How long you should exercise on a stationary bike per day is dependent on your goals and experience level. Those new to the stationary bike should ease in with around 30 minutes, 2-3 days per week. This could advance to 40 minutes, 3-4 times per week and eventually an hour, 4-5 times per week. Ultimately, however, consistency makes the biggest difference. For example, someone who does log an hour every weekday racks up five hours per week while someone doing 30 minutes twice weekly only logs one. However, if the hour-long rider quits after a month, the consistent, twice-weekly rider will surpass their effort in four months. The key is to find a frequency you can stick to for the long-term.