Cycling groups welcomed the Big Bike Revival scheme but said it should have been staged earlier in the year and much more was required.
The £450,000 initiative by Cycling UK - the former Cyclists Touring Club - follows a similar project in England.
Some 21,000 of those who took part last year said they now cycled more often.
The Scottish scheme, which runs to the end of October, will offer free bike checks, maintenance classes and cycle training to get former cyclists back on the road for short journeys.
Organisers said it would help towards the Scottish Government’s vision of 10 per cent of everyday journeys by bike by 2020, compared to the current 1-2 per cent.
Pop Idol winner Michelle McManus, who is an “ambassador” for the scheme, said: “I want to get fit and healthy and this seemed like a fun and environmentally-friendly way to do that.”
Mr Yousaf, who is due to officially kick off the scheme at bike recycler Recyke-a-bike in Stirling, said: “Cycling is healthy, cheap, fun and good for the environment. This exciting new project will provide a significant boost to community-led cycling and bicycle recycling projects right across the country.”
Cycling UK head of development Scotland Suzanne Forup said: “We all remember how fun and enjoyable a cycle ride was when we were kids, and that same feeling can be captured as an adult, too.”
However, Dave Brennan, of the Pedal on Parliament lobby campaign, said: “Whilst it is pleasing to see that the government wants to encourage cycling, there is no prospect of it reaching a 10 per cent modal share of cycling with initiatives like this.
“A significant increase in cycling will only come with a significant increase in funding for properly-designed infrastructure.”
Ian Maxwell, of Spokes - the Lothian Cycle Campaign, said: “Although the target of encouraging 20,000 people to get on their bike again sounds challenging, Spokes knows from our support of [bike recycler] Edinburgh Bike Station that there are a lot of unused bikes out there.
“Starting a campaign like this in September seems a bit late in the year. We hope there will be plenty of follow-up work in coming months to encourage people to use bike lights and making preparations for cycling through the winter.”