The move was to protest at the current ban on even bicycles on the system, with campaigners aiming to highlight the ease with which bicycles can be carried on.
Pedalpushers said their life-size cardboard bicycles and sculptures fitted easily in the fold-down seating area opposite the wheelchair spaces - proving that wheelchairs, buggies and bikes can easily co-exist.
Andrew Richards of Pedalpush-ers said: "It is absurd that even on a fairly empty tram on a Sunday Supertram don't see fit to increase their revenue and green credentials by allowing bikes of the non-cardboard variety to travel."
But Julia Shaw, commercial manager for Supertram, said: "Bikes would be dirty, greasy and can have sharp points. We were also concerned about people tripping over them and catching themselves in their chains or wheels.
"We did have a one-day trial last year and had few adverse comments from passengers or staff, but it was very tightly controlled and at busy times we feel it could cause conflict.
"At the moment it is difficult to see how to move forward."