Just wanted to share my experience with falls while riding backward:
When I ride backward, my butt leads my shoulders slightly, which puts my center
of gravity “ahead” of the wheel (relative to the direction of travel) but keeps
my upper body in a position which feels more natural than the leaning-backward
posture one might expect to be necessary for riding a unicycle backwards. I find
that this in itself makes falling off backwards less hazardous, as I can simply
put my feet down.
This works fine at low to medium speeds. Just train yourself to take your feet
off the pedals and put them on the ground if you feel yourself losing it. When
you “bail out” you should spread your legs apart so your feet clear the sides of
the pedals-if you simply lift your feet and try to put them straight down you
will often find that your legs or feet get tangled up in the pedals.
In a turn while backward riding, try to get the inside foot down first. And of
course, train yourself to grab the nose of the saddle with one hand so you don’t
drop the unicycle.
It gets a bit trickier the faster you go–you have place the feet a little
further behind you and/or lean a bit further forward, but anyone coordinated
enough to ride a unicycle at all should find this nearly instinctive. You will
fall off a lot when learning, but you will be going slowly so it isn’t really
anything to worry about.
If you get a foot on the ground but are still so unbalanced that you can’t avoid
falling down, bend your knees as you go down, tuck your chin to your chest, draw
your arms together with your elbows and forearms close together, palms facing
your forehead, and try to roll through instead of simply going ka-thud. It might
be a good idea to practice falling as described above beforehand.
In fact, falling down without hurting oneself is a very useful set of skills for
just about anyone involved in physical activities and increases one’s confidence
level dramatically. Many times it’s the fear of falling that turns a no-big-deal
fall into an injury accident.
With so many martial arts schools around these days, it would be easy to take
some beginner’s classes in judo, jiu jitsu or kung fu (for instance), or read a
book and practice the techniques.