How long should a 70 year old ride a bike?

Good day, I'm curious about the recommended duration for a 70-year-old individual to engage in cycling activities. As we all know, exercise is crucial for maintaining good health, but it's also important to be mindful of age-related factors that could potentially impact an older person's safety and well-being. With that in mind, could you please provide some insights into the optimal length of time for a 70-year-old to ride a bike, taking into consideration their physical fitness, health conditions, and any potential limitations? Thank you for your attention to this matter.