You are welcome. Think about how much and what kind of biking you want to do:
Want to climb 10,023 feet from the ocean to the peak of Haleakala? Go to Maui.
Want to tackle the Ironman Triathon route, visit a live volcano, go sports fishing or diving? Go to the Big Island.
Want to do a DIY vacation on a funky garden island, visit gorgeous, deserted beaches, climb a 10-mile, 3,000-foot deep canyon, enjoy plush resorts or rustic camping? Go to Kauai.
Want to visit Iolani Palace and the Bishop Museum, Banzai Pipeline and Diamond Head, Waikiki Beach, Punchbowl, the Battleship Missouri and the Arizona Memorial? Go to Oahu.
Want to get away from it all? Visit Molokai or Lanai.
You can't miss, but it's all different.