"It's a cycle, the only point of difference is you don't have to steer it and you don't have to balance it so it's accessible to a whole lot of people."
The company was also working on an electronically-assisted version, and eventually one for paraplegics.
It has only built the prototype so far but plan to build about 200 tandem bike units
"We based the numbers on what the Otago Rail Trail's doing and we think we'll do the same sort of numbers, which will mean we're setting off two or three hundred people a day," he said.
"We all know how cycling has boomed in the last five, 10 years so we wanted to fit in with that trend and we believe that this does quite nicely."
The bikes were designed so that, should a pair want to overtake slower cyclists, the bikes can be easily lifted off the tracks and fitted ahead of them.
"The other side of that is if you see a place where you want to have a picnic, of which there are hundreds, it's a very beautiful area, you can just stop, pull the bike off an have lunch."
The trail had been designed as a two-day ride, with people setting off from Gisborne, staying the night in Mahia, then heading to Wairoa the next day.
"You're in the saddle for about four hours a day; it's a pretty easy day."
Main hoped the first tourists would be on the trail by early 2018.
"We're supremely confident that this product is going to be an absolute winner," Main said.
"We're just over the moon that we've got it. It's taken six years to get to this point."
It would be up to New Zealand Transport Agency to decide if cyclists would be required to wear helmets on the bikes.
In November 2016 KiwiRail asked for expressions of interest from tourism operators to run services on the section of the Napier-Gisborne line, which was closed after major storm damage in 2012.
KiwiRail has reached separate agreements with Gisborne City Vintage Railway for the Gisborne-Muriwai section and with Napier Port for the Napier-Wairoa section.
KiwiRail spokesman David Gordon said Railbike Adventures would help to grow the region's economy by bringing a new, innovative tourism experience to New Zealand.
"It was important that we found the right fit for this section of the track, not just for KiwiRail but for the local community," Gordon said.