Overnight cycling. you can also come up with different activities to in the midst of the cycling to get the people to fulfill a task together or just having some sorts of challenge. It's all up to your creativity.
If your group is too old for games, then perhaps you can bring them on an eating session. cycle around Singapore to different landmarks and get them to try out different food for the whole night. Can exercise, can eat, can also enjoy the cooling breeze in the late night.
By saying all these, you can also plan a daytime cycling activity too if night time is not feasible.