In Porto bikes can be transported in trains and metro.
In the STCP bus company bicycle transportation is prohibited.
CP (Porto urban trains)
The Porto urban trains call at 82 stations within a 60 km radius of Porto along the following lines: Aveiro line, Braga line, Caíde/Marco de Canaveses line and Guimarães line.
Timetables and prices can be found here and Port network map can be found here (file in portuguese).
Bike transport is free every day and at all times on the Porto urban trains on all lines.
You can also leave your bike at one of the bike parks at the stations on the Aveiro, Braga, Guimarães and Caíde lines.
Metro do Porto
Metro do Porto has 6 lines, serving 87 stations distributed across the counties of Póvoa de Varzim, Vila do Conde, Maia, Matosinhos, Porto, Vila Nova de Gaia and Gondomar.
You can plan your trip and consult the tariffs in the webpage of the company.
It is authorized bicycle transport from Monday to Saturday at the times comprised between 10:00 and 17:00 and between 19:00 and 24:00 hours. Sundays and holidays transport is allowed anytime. This transport is free.
Bicycles have to enter the vehicle through the back door and are only allowed four bikes per vehicle, with the condition of not harming the comfort of other passengers.
The Trindade, Casa da Música, Senhora da Hora, Fórum Maia, Pedras Rubras and Póvoa de Varzim stations have parking facilities for bicycles.
Photos:
bicicletacomboio.wordpress.com(2); bragaciclavel.blogspot.pt; oprojetopedal.wordpress.com; livrodeviagens.wordpress.com; bicicletanoporto.blogspot.pt