If you're keen for an easy cycling cruise with lots to see, Warren Cole Walk and Cycleway along the riverside trail is superb. One trail end is by the Whakatāne River bridge on Landing Road; the other is near the Whakatāne Heads. It's fully sealed/paved.
You'll be alongside the river the whole way. Near the Whakatāne River mouth, you can watch the Pacific Ocean swell rolling in. Upriver from here, the Whakatāne wharves usually have plenty going on, perfect if you're with kids. About midway on the track, the river has large areas of salt marsh. If you enjoy bird-watching, there are many species to spot.