Sheldon Atovsky and Terry Gorman had the pink tandem bicycle custom-made. They say they would ride it for hours along the lakefront nearly every day.
Atovsky says he would steer while Gorman, who is blind, would take the back seat.
"We noticed people would wave or smile. So, we count the smiles when someone waves or smiles. I say, 'Ring,' Terry rings, and we count them every ride," Atovsky said.
"It's just such a fabulous and wonderful experience, can't say how wonderful it is," said Gorman.
The two used four different locks to secure the bike Friday while Gorman went to a doctor's appointment at Northwestern Memorial Hospital.
But when they came back out, the bike was gone.
Anyone with information can contact Chicago police.