Cyclists in London could be forced to use new bike lanes and banned from other parts of the road, according to Boris Johnson.
The mayor is in talks with senior officials at Transport for London about making Cycle Superhighways 'mandatory'.
A ban on cyclists using other traffic lanes appeared to suggest the possibility of fines.
The rule is likely to apply only to fully segregated bike lanes where a physical barrier protects cyclists from other traffic.
TfL is spending more than £60m to create two new superhighways from Kings Cross to Elephant and Castle and from Tower Hill to Lancaster Gate.
Some existing bike lanes are also being upgraded to fully-segregated status.