Is it possible to learn to ride a bicycle as a grown man if have never rode one in my life?
Yes it is certainly possible to learn to ride a bike as an adult. Although it will take more time than it would have taken you as a kid it is never too late. How long it takes varies from person to person, but don't be discouraged if it takes a few days. Here are some tips:

- Try to enjoy the learning process and don't get discouraged if it takes some time.
- Get a bike that is the correct size for you. 
- Consider getting a helmet. 
- Find a safe space to practice.
- Practice getting on and off your bike.
- Practice breaking.
- Try coasting without pedals first.

Good luck! And don't forget to have fun!
yes, as long as you can still use both of your leg.
Yes, it's true that the ability to use both legs is important in learning how to ride a bicycle. However, there are adaptations that can be made for individuals with physical disabilities. For example, individuals with prosthetic legs or individuals who use wheelchairs can learn to ride a bicycle with the help of adaptive equipment and the guidance of an experienced instructor. If you have any concerns about your physical abilities, it's always best to consult with a doctor or physical therapist for advice.