More than 800 miles - around 80% - are to be removed from Northern Ireland's cycling network and reclassified due to the danger of increasing traffic.
The National Cycle Network (NCN) currently has over 1,000 miles of routes running through Belfast and Londonderry and connecting many towns with the countryside.
Most of the land is owned by the Department for Infrastructure (DfI) and is used for around 30m journeys a year, two-thirds of which are by cyclists.
The cycling charity Sustrans, which created the NCN, conducted a national review in 2018 which showed that many sections are no longer suitable for cyclists due to an increase in the volume and speed of traffic.
A spokesperson for Sustrans NI said 848 miles will now be reclassified in July and promoted as part of new named routes. This means some sections of the named cycling routes will not be part of the official national network. In addition, a further 6% (37 miles) will be removed from the network altogether and cease to be promoted.
The aim is create a smaller but safer network, allowing cyclists to make an informed choice about different routes they take.
The Sustrans spokesperson said the new network should help to bring more business from cyclists to rural areas in Northern Ireland.
"Over the past 20 years many of the routes which were once on quiet, country roads have become much busier, with fast traffic making cycling or walking on them both dangerous and unpleasant.
"In the long-term, Sustrans' aim is to reroute on-road parts of the NCN to new traffic-free sections, or create new protected infrastructure."
The NCN review follows a recent announcement from Stormont minister Nichola Mallon of a £20m infrastructure investment that includes cycle and walking greenways.
Local councils have also been drawing up community development plans which Sustrans says provides a further opportunity to expand the network.
Just 14% of the cycling network is traffic-free at present, but this accounts for most usage, with routes connecting major urban centres in Belfast, Londonderry, Portadown and Newry.
The remaining 86% is on roads, including the coastal Belfast to Ballyshannon route and the Kingfisher Trail which runs through the Fermanagh Lakelands and across the border into Donegal, Leitrim and Cavan.
Sustrans say they will use the reclassification to promote cycle tourism in Northern Ireland with the use of new named routes.