It was a path well off the beaten track that John Key thought most appropriate to launch the New Zealand Cycle Trail project.

The Prime Minister turned the first sod to launch the cycle project he first promoted in February and construction of the final two sections of the 100km long Waikato River Trail at Little Waipa Domain, north of Tirau, yesterday.

The $50 million cycleway, which will run from the Far North to Bluff, will be built in stages over the next two years.

Asked why he chose to launch the 1400km series of national trails in the South Waikato, Mr Key said it was important to complete the Waikato River Trail in time for next year's world rowing championships at Lake Karapiro.

Mr Key, who admitted he was "probably not a fan" of spandex, said the trails would also open up isolated parts of New Zealand not only to locals but the tens of thousands of tourists he expects to visit long-term as a result of the initiative.

"That was really a big part of the idea behind the cycleway, to open up the countryside and bits of NZ that are harder to access and people hardly ever go to."

Green Party MP Kevin Hague, who rode 30km from Cambridge for the sod turning, said the tourism benefits of the project were enormous but its success depended on cyclists' safety.

"If visiting overseas cyclists feel unsafe riding on our roads their enthusiasm for our cycle trail back home will be muted at best."

Mr Hague said cycle trail projects were highly successful overseas, with 386 million journeys recorded last year on the UK National Cycle Network.

Cycling Advocates Network co-chairman Glen Koorey also welcomed the project, saying the initiative could give motorists likely to ride the trails a better appreciation of some of the issues cyclists face. But he hoped in the long-term the Government would look at a network which linked into urban areas.

"I think that is going to help make the difference in terms of safety," he said.

Mr Key said work had also begun on the $1.03 million, 245km Tongariro and Whanganui National Parks trail.

Decisions are yet to be made on the feasibility studies on four other trails on the Hauraki Plains, the Far North, Central North Island Rail Trail and Southland/Queenstown Lakes, although work is expected to begin on most of these next month.

Mr Key allocated $9 million out of the $50 million set aside for the cycleway in the Budget for the tracks.

The idea of a national cycleway was presented at the Job Summit in February to help get NZ through the recession.

Seven cycleway projects are scheduled for quick starts, including the Waikato River Trail. Among these are:

* The Hauraki Rail Trail - two linked trails running from Paeroa to Waihi and Paeroa to Thames, in the Thames Valley. Feasibility study to be completed by December 18.

* The Far North - possible routes being examined for a 90km trail. Feasibility study expected by December 18.

* Central North Island Rail Trial - a proposed 60km trail costing $4m awaiting further study on design and construction.

* Mountains to the Sea - construction of two trails creating a 245km ride in Tongariro and Whanganui National Parks. Initial construction begun in parts, with date of completion not yet known at an expected cost of $1.03m.

* St James Trail - 50km mountain bike trail being built by Conservation Department by late 2010.

* Southland/Queenstown Lakes - Decision on potential 175km trail expected by December 18.