The Kaipara District has an ever-increasing number of trails and routes to explore by bike. From the purpose-built mountain bike park in Dargaville to the gentle wide Ruawai Stopbank Trail. Or check out the Kia Iwi Lakes trails, and finish up with a swim in the lakes. If you are more of a gravel rider there are numerous rural roads to explore. Including the route between Dargaville and Auckland titled the Kaipara Missing Link.
The Kaipara District Council has more information on their website on the Walking and Cycling page.