An Taisce said the plan, which will involve large illuminated advertisements across the capital, was against EU law.
Its request to An Bord Pleanála to bring a review of the project before the High Court was refused.
The board began the first of four days of hearings on the plan, which has been submitted to Dublin City Council.
Local councillors, city centre businesses and residents are objecting, claiming the advertisements could distract drivers and divert attention away from existing shops and it is not a good deal for the city and its residents overall.
The council’s deal with operators JCDecaux would see at least 450 bikes provided free at 25 locations, and four public toilets, in exchange for 120 advertisement boards.
In Paris, the company has given more than 2,000 free bicycles to the city, where residents and tourists use a card with a deposit to travel from one location to another.
It is hoped the project in Dublin would see a crop in the number of cars entering the city centre.
However, An Taisce says the additional advertisements would clutter city landscapes. Maurizio Passi, with local business Tiffany Blinds, warned the advertisements would distract from city centre businesses themselves.
Hearings at An Bord Pleanála are due to continue for at least another three days.
Others due to appear before Inspector Jane Dennehy include representatives from Arnotts and Eason, residents from North Great Georges Street, local advertisement companies and local councillors.
The free bikes scheme already operates in cities including Vienna and Paris. Plans in Dublin would see some commercial signs as big as seven square metres erected on structures or buildings.
Some city councillors are objecting, saying other cities have received more bikes and better deals than that agreed with the Dublin City Council.
Hearings will continue today.