Concern over possible cuts to cycling promotion cash
Campaigners are calling on the Scottish government to abandon plans to cut the amount it spends promoting cycling and walking.
Environmental groups argue the funding cut, of about a third, would make it harder for ministers to meet many of their own targets.
But the government insists it is committed to reducing car use.
Cyclists gathered for a rally outside the Scottish government's headquarters at St Andrew's House in Edinburgh.
Encouraging Scots to cycle or walk more, and use their cars less, is seen as a relatively cheap and environmentally-friendly way to reduce carbon emissions, congestion and obesity.
However, sustainable transport campaigners Transform Scotland said there had been a 33% reduction in spending to promote walking and cycling, from £18.5m in 2011-12 to £12.6m in 2012-13, when the overall transport budget had increased.
Tom Ballantine of Stop Climate Chaos Scotland said: "The decision to cut funding to support low carbon transport measures such as active travel is deeply worrying.
"A number of parliamentary committees have echoed our concerns that the budget and spending review is not aligned with Scotland's climate change ambitions.
"The government must now step up and fully fund all of the measures set out in its own plans to meet our climate change targets."
But the Scottish government has defended its record on investment in cycling and walking.
Transport Minister Keith Brown said: "We've spent more than £80m on active and sustainable travel since 2007. We have substantially expanded the cycle networks, for example.
"There is no question that we would like to spend more but we have a 36% cut to our capital budget and we have to live within the resources that we have."