I congratulate you on getting you son started so early. So many kids today are told to strap on a helmet along with their underoos and they don't leave the house without a layer of bubble wrap to keep them safe.
I think kids need things that allow them to experiment, learn their boundaries, get in trouble (a bit) be held responsible for damage to themselves and to others and to property.
Don't just yank the training wheels off, hand him the wrench and talk him though it. Not only will he learn "lefty loosy", he'll learn pride in accomplishment and confidence with his hands. Next comes the spark plug wrench and when he cracks the frame from jumping over the septic tank hand him the torch and teach him to weld.