Susan MacLucas specializes in teaching cycling to adults who never learned as a child. But personally I think the method she uses is safer for children, too. Occupational therapists who specialize in helping children with sensory integration issues use a similar method. The key is in taking off the pedals and learning to glide and balance first, rather than using training wheels to give the immediate impression that one is riding a bike only to require intense supervision and re-learning as the training wheels rise and come off. Once my kids could glide and had the hang of steering, which happened fairly quickly, I felt much better letting them be alone as they mastered the skill. And they felt better, too. Who needs the pressure of surveillance when you might feel weak or frustrated?
If you can’t arrange for personal instruction at her Bicycle Barn in Somerville, MA, you can read about how to teach yourself or your child at her website.