Take a look at the Stumpy Creek Olympic course which goes right through Lake Norman State Park, but traffic starts to get thicker after 10:00:
http://jonesracingcompany.com/stumpy-creek/ If you are not leaving early I would recommend the Lake Norman YMCA Sprint course, you can bike to it and there is much less traffic. You will see many solo and group riders. You can easily add distance on any of the back roads headed towards Troutman or Statesville, there are not major hills but lots of rollers. Many weekends the Lake Norman Y holds open water swims and lots of bikers depart after that but there is not anything scheduled for the weekend of July 1st.
http://jonesracingcompany.com/...normanymcatriathlon/ Sprited Cyclist in Davidson used to have a 32 and 50 mile ride leaving at 8:00 (you could bike or drive to it from LKN State Park)
http://www.spiritedcyclist.com/about/rides-pg69.htm The Trek Shop in Huntersville (Exit 18 off of 77, you would probably want to drive to it) has Saturday morning rides also.