The National Transport Authority is concerned parts of the city centre could be off limits to cyclists once the new Luas Cross City Line is up and running.
A draft report in today's Irish Times shows transport chiefs believe certain sections of the line will be too dangerous for those on bikes.
That's because there either won't be enough space for both trams and cyclists, or certain junctions could prove lethal if wheels get stuck in the grooves.
A draft report in March highlights how crossings should be made at 90 degrees to reduce the risk of wheels getting caught. The NTA warns that if that isn't possible it will mean cyclists have to divert.
However that could mean large tracts of the city like the Henry Street area would be out of bounds, which in turn would dissuade people from getting on their bikes.
The NTA is asking the city council and Transport Infrastructure Ireland to take action to address their concerns.