Like wiki, riding a bike can be easy to do but hard to learn. Both are elemental. They have exactly what is needed and little more. More would make it not a bike or not a wiki.
# Tipping
A bike will tip side to side. Learn to tip yourself with the bike whenever you want.
Sit on the bike while someone holds it still. Tip a little each way back and forth. Try this with your feet off of the pedals and then back on again. Continue until you know the feel of tipping.
Sit on the bike while someone holds and pushes you at a walking pace. Learn to use the handlebar to tip whenever you want.
Keep your feet on the pedals whenever the bike is moving. You and the bike should always tip together.
Wiggle the handlebar just a little and wait for the bike to tip. Wiggle and tip both ways, back and forth, slowly at first then faster or further. Continue until you can tip either way without thinking.
# Stopping
A bike's brakes will make it stop. Learn to tip yourself and the bike together while stopping.
Sit on the bike while someone holds and pushes you at a walking pace. Tip one way or the other with the handlebar and then stop with the brake. Put one foot down to hold the bike up the exact moment it stops. Practice stopping while tipping both ways.
Your helper will spend less time holding you upright as you take more control of your bike. Continue until you can stay upright starting and stopping with your helper only pushing gently with one hand.
# Pedaling
A bike's pedals will make it go. Learn to pedal slowly in a low, easy gear.
Sit on the bike while someone holds and pushes you at a walking pace. Turn the pedals so that you feel pressure in your toes all the way around. Push a little harder. Feel more pressure. Now harder still. As you go faster your helper will be getting tired. Press harder still and ride away alone.
Stop with the break to let your helper catch up. Start together again. Ride away. Steer in gentle turns both ways. Continue until you can pedal, steer and stop without thinking.
# Starting
A bike will get going with one half revolution of the pedals. Learn to start moving fast enough to tip and turn without more pedaling.
Sit on the bike holding yourself up with one foot on the ground and the other foot ready to push a pedal half way around. Halve someone nearby to catch you if this doesn't work first time. Press firmly on the one pedal while lifting your other foot to its own pedal. Tip, steer and pedal as needed to keep going.
Try starting with the other foot on the ground. Continue staring and stopping tipped both ways until you are comfortable without your helper nearby.
# Riding
A bike will be easier to ride when going faster than a walking pace. Learn how steering changes when you speed up and slow down.
Have your helper get their bike to ride with you. Ride side by side with your wheels spaced like those of a car. Steer to stay this distance. If you get too close, stop.
Start and stop over and over. Let your helper match your speed while you steer to stay comfortably spaced.
Try riding faster. Try following your helper's speed. You will be traveling over more ground than before. Continue riding until your mind is free to choose directions and watch for hazards.
# Skills
There are many new skills to master once you are riding. Learn new skills that are small variations on things you already do without thinking.
Try starting your bike with you standing beside it. Standing to the left, put your left foot on the left pedal. Push to start and coast while you lift your leg over the seat, find its pedal, sit down and start riding. Try the other side too.
Watch how other people ride. Learn how they go fast while saving energy. Watch how each rider chooses positions on the road, avoids hazards, and finds their special joy riding. Make that your joy too.