Two in three commuters think roads are unfit for cycling, according to a survey.
Many workers would be persuaded to cycle if roads were safer, the poll by road safety charity Brake and solicitors Bolt Burdon Kemp found.
Nearly half the 1,550 adults questioned, all of whom were in work or in education, said they cycled already.
However 64% of these only cycled occasionally and only 10% used their bikes as their main form of transport for commuting.
The survey also showed that 35% would switch to cycling to work if the route was less dangerous and 46% would make other journeys by bike if roads were safer.
Only 15% of those surveyed said they had widespread 20mph limits in their area.
Of those who do not have widespread 20mph limits, 73% would support having them and 83% would back measures like cycle paths being introduced in their community.
Brake deputy chief executive Julie Townsend said: "It's positive the Government is working to encourage cycling to improve health and reduce pollution, but it must also ensure roads are safe for cyclists.
"Widespread 20mph limits and cycle paths where people live and work would encourage more people to cycle, without their lives being threatened by fast traffic."