Although 90 kilometres may seem a bit of a stretch, this ride is almost completely flat and, with a tail wind, can be completed in a single day. The first leg of this trip takes you along state highway 2; busy, but safe enough, with mostly wide road margins through to Te Puke (a pleasant service town with camping, supermarket & cafés).
Soon after Te Puke the Tauranga/Rotorua traffic turns off onto highway 33 while you continue along the now considerably quieter highway 2. Here you wind your way a further 20 or so kilometres through farm land till you reach the coast. There are several camping options along the coast, at Pikowai, Kohioawa, Matata (store, café) and Thornton.
Whakatane is a large-ish town and has everything you need. The campground here (there is only one) is very pleasant indeed - set in a reserve along the banks of the Whakatane River and just a few minutes from town.
From Whakatane you have the opportunity to take a boat excursion to White Island, one of New Zealand's most active volcanos. The island is visible right along the cape, often covered in a plume of smoke.
While in town make sure you visit the information centre and pick up a free copy of Opotiki, East Cape & Beyond via the Pacific Coast Highway. This excellent booklet provides useful background on the settlements along the East Cape, including camping options and places where you can get something to eat or stock up on supplies.