When I first started climbing I was instantly attracted to this exercise and after trying and failing many times, I made it a goal to be able to do this exercise. Well after some research, hard work, and experimentation, I am now able to pull a pretty decent front lever.
I have worked with many different athletes thus far in my career and feel as though this movement can be trained and performed by a variety of athletes other than climbers and gymnasts, but it takes proper progressions to get to that point. And yes, I know body proportions will make this movement much more difficult for some to complete, but the gentleman above (John Gill) was over 6'2 and was said to be able to hold a front lever for over 30s while holding a conversation.
Here are some progressions to experiment with, along with some suggested set and rep schemes for each exercise. Still working out the kinks of this whole video making and posting so bear with me until I get it on lock down! Part 2 will focus on other progression schemes as well as some advanced front lever variations.