Both of my girls had issues with learning to ride bikes. Dd11 was somewhat harder, though, b/c she is very cautious by nature. Both of them were impacted by perfectionism. It didn't help that dh kept insisting that putting the seat down low was a bad idea, so we didn't have the parents on the same page in terms of how to teach them.
I wasn't really worried when they were your ds' age - maybe b/c that's about the age when I learned to ride myself. With dd11 we put our collective feet down on learning to ride when she was 10 b/c she was a 6th grader at that time and it was becoming a social issue. She kept insisting that she was going to fracture her hip if she fell. Like most things, she finally got it down when we gave up on trying to teach her and let her teach herself in whatever manner she could.
