What is the secret of two wheels

My husband and I have always encouraged our son to ride his bike.  At the age of 2, we got him a balance bike (a bike without pedals that allows children to learn the most important aspect of riding - balance).  He quickly took to it and would race around super fast.  Once he was buzzing all over and feeling really stable, we added pedals to the equation.  He was probably around the age of 3 and a half at the time. 

By the time we moved to Japan, our son was 4 years old and was really good at riding.  The thing he wasn't used to doing was ride around other people.  In the US he mostly rode in our long driveway and at parks.  For the longest time, he would ride at the park in Japan, but we didn't let him ride around the neighborhood or in streets.  We've finally crossed that bridge, but it has been very nerve wracking.

I've always been told that if a foreigner in Japan gets into a bike accident, it is automatically their fault.  I've even heard of non-Japanese people wearing GoPro cameras while they ride so if there is an accident, they can at least have the benefit of the doubt.  Because of this warning, I've been very nervous releasing my son onto the streets of Tokyo.  He typically rides on the back of my bike (safely secured in a child seat).  I feel like I'm holding him back by gasping and constantly reminding him "look out for other bikes"  and "are you paying enough attention?"  Typically, I'm a very relaxed parent.  But I cannot relax when I have this negative image in my mind that if something bad happens I won't be able to handle it and it will be all my fault.

My son is very capable on his bike.  I watch other moms and their relaxed attitude with their kids on bikes.  I need to show him the confidence that he has earned.