Completion of the Great Glen cycle route linking Oban to Inverness has been brought forward as part of the funding package announced by Transport Scotland.
Upgrading the route by 2015 will set in motion a major new tourism attraction in the north as well as boost the economy in the surrounding communities, Transport Scotland said.
Cycling body Sustrans is already engaged in a programme of improvements on the route but the additional £3m funding announced on Wednesday will ensure cyclists can avoid trunk roads, where they have to travel alongside lorries and cars travelling at up to 60mph, for the entire journey.
A further £500,000 has been earmarked for improving cycle access to stations and routes alongside the £300m Airdrie-Bathgate rail link, completed in 2009, and another £400,000 will be spent on increasing cycle parking at schools.
The investment was welcomed by cycling groups who said the cycling element had been protected despite a drop in the overall level of funding.
Campaign group Spokes said it took the level of investment in cycling to just more than 1% of the total transport budget, though this is less than the 5% it has claimed is necessary to ensure the Scottish Government meets its target of 10% of all journeys being made by bike by 2020.
The announcement comes after Transport Minister Keith Brown said he aimed to make 2013 the year of pedal power following a surge in interest created during the Olympics.
Mr Brown said: "The Great Glen cycle path will be an iconic route that will boost the local economy through the additional tourism in an area which already attracts more than 20,000 spectators to the World Mountain Bike Championship each year in Fort William."
The bulk of the money – £2.6m – will go on the Corron Ferry to Inverness section of the Great Glen route, taking cyclists off the A82, with a further £400,000 spent on the Oban to Appin section, creating an alternative to using the A828.
In 2010 – the most recent figures available – bike journeys accounted for 298 million kilometres, an increase of 23% compared to a decade earlier.
John Lauder, Sustrans Scotland director, welcomed what he described as a "windfall" investment but said he would like to see funding increased in a more planned way.
He said: "It will help provide a planned, signed and mapped alternative to using trunk roads between Oban and Inverness. It shows we are moving in the right direction and that the Transport Minister has got confidence this investment is producing results."
The number of cyclists who were killed or seriously injured increased 12%, from 145 to 163, in 2011, according to Scottish Government figures released last year, though part of this was thought to be due to more people travelling by bike.
Dave de Feu, a spokesman for Spokes, added: "Given that we have this target of making 10% of all journeys by bike by 2020, having just 1% of the transport budget spent on cycling is just hopeless.
"If you look at European countries that have been successful in achieving a significant increase in cycling levels, 5% is a much more appropriate figure."
He added that, of Scotland's 32 councils, only Edinburgh had agreed to spend 5% of its transport budget specifically on measures to boost cycling.