A Filipino domestic worker who went cycling with two friends on Pulau Ubin on Sept 27 ended up in intensive care for 10 days.
Ms Calapini Marilou Garcia, 50, underwent two operations because of swelling in her brain.
Exactly what happened to her on that Sunday outing remains unclear as her friends suspected something was amiss only after reaching the bottom of a slope without her.
They backtracked and were shocked to find Ms Garcia lying on the ground in a daze next to her rented bicycle. All three riders were not wearing helmets.
"She was still conscious. There were no bruises or bleeding, but she kept saying that she was feeling giddy as she was lying on my lap," Ms Clarissa Rigdao, 43, one of the friends, told The New Paper (TNP).
Two passers-by who stopped to help called the police.
Ms Rigdao said her friend started vomiting before the police arrived.
Ms Garcia's employer, Madam Jeanette Mok, told TNP that Ms Garcia was conscious when taken to Changi General Hospital, but her condition deteriorated quickly.
The doctors had to perform two procedures - the first to insert a pressure monitor into her brain and the second to remove a part of her skull to ease the increasing pressure because of swelling in her brain.
Madam Mok, a 37-year-old couples counsellor, said: "The surgeon told us that based on the areas of the brain that were injured, she could lose her ability to speak, her motor functions and her memory."
Early last week, though, Ms Garcia showed signs of recovery, as she was able to move her eyes and squeeze her fingers.
Last Monday, Madam Mok arranged a video call between Ms Garcia and her family in Ilocos Norte province in the Philippines. Ms Garcia was able to wave to them, and recognised her teenage son.
Last Wednesday, she was moved to a high dependency ward after 10 days in the intensive care unit.
Ms Garcia, who also has a daughter, has been working in Singapore for almost 20 years. She started working for Madam Mok in January.
Madam Mok said she and her husband, Mr Brian Mak, 37, who works in technology, have been waiting anxiously for good news throughout Ms Garcia's ordeal.
Describing Ms Garcia as responsible, conscientious and caring, Madam Mok said: "She takes care of us very well. She is also affectionate towards our pet dog and spoils him regularly.
"This ordeal has been difficult because she is a good person and we cannot believe something like this has happened to her."
Ms Rigdao, who has known Ms Garcia for about five years, described her friend as cheerful and said she was like an older sister to her.
Mr Steven Lim, Singapore Cycling Federation's vice-president for safety and education, said: "The helmet is a mandatory requirement for anyone cycling on Singapore roads.
"Rules aside, it is about taking precautionary measures against serious injuries. A helmet will protect the cyclist should he encounter a fall and run the risk of a serious head injury."
Mr Lim said cyclists should bring their own helmets when renting bicycles, as rental of helmets may not be feasible for hygiene reasons.
Madam Mok said the hospital bill has reached $52,000 so far, while the insurance coverage for Ms Marilou is only up to $20,000.
Madam Mok and her husband have gone on fund-raising platform Give.asia to raise money, as the bill is estimated to exceed $200,000. As at Saturday afternoon, more than $76,000 had been raised.
