Tom_hampton wrote:
That's tough. We'll, it's easy to say... But, the reactions have to be instinctive to be effective. The problem is the natural instincts are wrong. We all want to catch ourselves. But that puts all the fragile parts in the way when going down. The only way to unlearn the wrong instincts and learn the right ones is practice. Who wants to practice crashing?
So I think actually falling a lot in other sports - that is tumbling, skiing, dance, gymnastics, martial arts, volleyball, etc. - will help instinctively with falling on the bike. You're spot on that we should not try to catch ourselves when hitting the ground - rather we should slide or roll.
That said, if the OP is concerned about crashing, perhaps a more useful thing would be to practice not crashing in the first place. Here's something I wrote about that
https://medium.com/@johntomlinson/staying-up-607a3bf88de4
http://www.jt10000.com/