In June 2002 I spent 10 days biking 650 km around Northland,
starting at Whangarei and going by way of Dargaville, Waipoua Forest, Rawene, Kaitaia, Cape Reinga (staying at Waitiki Landing 20 km south), Taipa,  Kerikeri, then back to Whangarei.

The terrain is moderately hilly, the forest and coastal scenery are magnificent, the people are very friendly, and the weather was showery but warm. Overnight stays in motels and cabins are easy to find, but campgrounds are usually closed in June. I recommend the extra 240 km (round trip) up to New Zealand's northernmost road access at Cape Reinga because of the great scenery.

In June 2004 I made the tour in 5 days, going in the opposite direction and using my road bike instead of the mountain bike of the first trip. Also, I went up the east coast during a high pressure weather system and down the west coast in the calm winds of the centre of the system, thus mostly avoiding head winds. I stayed at Kawakawa (Star Hotel) after an afternoon ride from Whangarei, Kerikeri (a very good YHA after the morning ride from Kawakawa), Kaitaia (Wayfarer Motel), Opononi (backpackers near the hotel), and Dargaville (Northern Wairoa Hotel). Hotels are usually in the centre of town, are clean, and don't cost much more than a backpacker dorm room.

(The pictures are in roughly geographic order.
Put the cursor over a picture to see its caption.)