Work began on the Clutha Gold Trail extension from Lawrence to Waihola in August 2020.
The trail already runs for 73 km from Lawrence to Roxburgh, where it joins a further trail network extending into Central Otago.
The new section, available to riders this summer, runs from Lawrence to Milton, a distance of about 37 km.
Riders had already begun using the 11km Lawrence to Waitahuna section, which was "basically finished", Mr Paterson said.
"It’s fantastic to see local entrepreneurs have already started taking advantage of the opportunities this extension will offer, by setting up a coffee cart at the former Waitahuna [railway] station.
"The extension will be a great resource both for people who like to ride, and for those wanting to build businesses on top of that."
Figures for the past year show the original Clutha Gold Trail hosted 12,579 riders, an increase of 21% over the previous year.
On the Waitahuna Railway Station and Goods Shed Facebook page, coffee cart owner Ailsa Rose said support for the new venture during its opening weekend had been "amazing".
"We had another amazing day today, with lots of beautiful locals dropping in, and a few passing cyclists, too," she said in a message posted on Sunday.
She and partner Bob Corona began a restoration of the former railway station and goods shed - visible from State Highway 8 at Waitahuna - in 2019.
The project was still undergoing construction, Ms Rose said, and the century-old building’s eventual use remained to be confirmed.
Mr Paterson said a potential March opening date for the full ride to Waihola had hit "a couple of snags".
"We hope to be finished towards the end of next year, allowing people to ride from Roxburgh to Waihola.
"We’ve experienced some supply chain issues with materials, and some technical difficulties with boardwalks on the way to Waihola, but we’re confident everything will fall into place."
The final cost of the extension could be about $12 million, Mr Paterson said.
