A bicycle transmission shifting device that includes a cable having a portion of the cable attached to a derailleur and also having another portion of the cable attached to a cable drum. Rotation of the cable drum in one direction pulls the cable to move the derailleur to move a bike chain in a first direction to change gears. Rotation of the cable drum in a second direction pulls or releases tension in the cable to move the derailleur to move the bike chain in a second direction to change gears.