The woman was admitted to the Ryhov hospital in Jönköping, southern Sweden on Saturday. According to local news reports it was a single-person accident.
On Saturday afternoon, Eva-Lena Frick, CEO of Vätternrundan, told news agency TT that the organizers did not have any details about the circumstances of the accident but had received notice that the woman was in a stable condition.
"We do not know what caused the accident," Frick said.
Vätternrundan is an annual event in which around 20,000 participants complete a 300-kilometre circuit around Lake Vättern.
The event started at 7.30pm on Friday night and finished at 6.30am on Saturday morning.
Every year, around 50 cyclists end up in hospital during the race, according to TT.
"We get a few wrist fractures, collarbone fractures, grazes and the odd concussion. Accidents with cars involved are thankfully extremely rare," said Frick.
All participants have to sign a form vowing not to drive for at least six hours after completing Vätternrundan.
The event got off to a dramatic start on Thursday when a dog attacked one of the participating cyclists. He flew off his bike, landing on his face.
The dog, called Atos, had been missing for over a week and Facebook page titled "Atos wants to go home" was set up to help find him.
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