Yesterday Daughter finally asked to practice without side wheels on her bike. I took her to the sidewalk with proper practicing gear (a helmet and vest to grab her when she falls) and for half an hour she tried. As she is a perfectionist she wanted to quit after two minutes, but with a little encouragement the practice session lasted half an hour. All with my support.
This morning Daughter wanted to try again. We went to the park. The idea of falling on the gras instead of pavement gave her more confidence. Within 20 seconds I felt she had balance and I let her go. She went on. And on. And on. She is now a proper biker!