The gyroscopic theory is incomplete but at 25+ MPH there are significant gyroscopic forces.
Also, while a riderless bike is fairly stable, a rider overpowers the autocrorrective nature when they hold the handlebars. So, really bikes are stable in large part because the rider balances for the bike as seen by your ability to keep a bike upright without moving and it becomes far easer to do so at as you speed up.
Also, while a riderless bike is fairly stable, a rider overpowers the autocrorrective nature when they hold the handlebars. So, really bikes are stable in large part because the rider balances for the bike as seen by your ability to keep a bike upright without moving and it becomes far easer to do so at as you speed up.