Charity Cycling UK said that a “long-term and well-funded communications campaign” is needed to make people aware of the update.
The Highway Code, which contains advice and rules for people on Britain’s roads, is expected to be amended next month to introduce a risk-based hierarchy of road users.
For the first time, the law will require those who can do the greatest harm to others to have a higher level of responsibility to reduce the danger.
This means for example that someone driving will have more responsibility to watch out for people cycling, walking or riding a horse, and cyclists will have more responsibility to be aware of pedestrians.
The Department for Transport (DfT) insisted it will ensure “all road users are aware” of what is happening.
Provisional figures from the department show 4,290 pedestrians and 4,700 cyclists were killed or seriously injured in crashes on Britain’s roads in the year to the end of June.
Other key amendments to the Highway Code include clearer guidance for drivers to leave a minimum distance of at least 1.5 metres when overtaking cyclists, and instructing drivers to give way to pedestrians waiting to cross roads at junctions.
There will also be a recommendation for car users to reduce the risk of opening a door into the path of a cyclist by using the hand on the opposite side to the door, as this will often lead to them looking over their shoulder.
This is known as the Dutch Reach technique.
Cycling UK’s head of campaigns Duncan Dollimore expressed concern that the revisions to the Highway Code “are not being communicated”, and “will be of limited benefit if the public aren’t aware of them”.
He said: “Many people won’t have read the Highway Code for years so it’s essential that the key changes are clearly explained, with simple, accurate and memorable messages.”
A DfT spokesman said: “The department has established a working group of key organisations to ensure that messages about the changes are as widespread as possible.”
Changes to the Highway Code will come into force on January 29 if they are approved by Parliament.