You need to know How to do a Wheelie
My wife just about had a hissy fit when she learned that my physical therapist was teaching me how to do a wheelie. She said she'd kill me if I died on her. She couldn't see any reason for me to learn how to do something that seemed dangerous to her. I don't consider doing a wheelie any more dangerous than riding a bicycle. It takes several hours to learn how to ride a bicycle and it takes about the same amount of time to learn how to do a good wheelie. But why do a wheelie in the first place?
If you are fairly mobile with good arm strength and coordination you will probably spend a lot of time outdoors on some pretty steep slopes. You will need to be able to go up and down steep hills and driveways. Going up takes strength. Going down takes a wheelie - alllll the way down!
Going down a steep hill on all four wheels is dangerous because it tips you forward to the point where you can actually fall out of the chair or tip the chair over. Not good. The solution is to tip back into a wheelie and use your hands as brakes to control your descent. The wheelie position is comfortable because it is always a balanced rocking-chair position no matter how steep the hill. I am wearing gloves here because friction will burn my bare hands if I go down a long hill. This doesn't look like a steep hill, but I assure you it is.
You may want to cross a yard or section of dirt in your wheelchair. Grass and soft ground can stop you in your tracks if you try to cross it on all four wheels. The front caster wheels tend to get stuck in holes. Tipping back into a wheelie to cross the grass keeps the casters from sticking.
You will eventually run into a situation where you have to go down a six inch curb because there may not be a ramp from a sidewalk to the street. If you fail to raise the front wheels when you go over the curb you'll end up on your face in the gutter. The solution is to tip back into a wheelie, carefully drop over the curb to the street, and only then drop back to all four wheels. If you feel like showing off, you just stay up on two wheels and roll away to the amazement of friends and family. If you get good at going down six inch curbs, you can even learn to go down consecutive curbs - stairs! But, don't try this if you haven't had proper training! I know a really athletic, talented paraplegic who broke a vertebrae going down stairs. Well, actually, he was going down an escalator backwards in his wheelchair, but that's another story.
A related skill is going UP a six inch curb. First, you have to practice on two inch and four inch curbs. (I'm practicing on a four inch curb here.) Going up a curb requires a short wheelie followed by leaning forward and pressing forward on your big wheels when your tires touch the curb. It take practice to perfect the timing.
Not every paraplegic needs to know how to do wheelies. But, if you're young and athletic and participate in a lot of outdoor activities, wheelies can help you. Just be certain you get the proper training before you try them. A trained physical therapist taught me, and then my wife helped me, and then I graduated to training on my own with a helmet to protect my thick head and gloves to protect my fingers. Even then, I've accidentally gone over backwards in my wheelchair seven times. Would you believe it? My physical therapist even taught me how to do that safely!