A brave article, considering the responses you’ll be getting. You don’t need to learn how to ride a bike. You need to learn how to start and stop a bike. In between is just coasting and steering. For that, you can get a velocipede. (or take the pedals off your bike to get them out of the way).
Also, don’t listen to the idiots at bike shops that adjust your seat too high so you can’t get on and off comfortably. Not everyone is going to enter that stupid race in France. Maybe borrow a woman’s bike for a while (much easier to ride, and to get off when you start to fall).
Being tall myself, I empathize with your altitude sickness. Let us know when you’re ready to get a motorcycle. ;) I think it’s a lot easier than a bike. Pedaling is a distraction from the scenery and the armor looks so much better!