"It's not uncommon in the summertime for us to have bicycle accidents," Tiburon fire Capt. Sloane Valentino said. "It's unusual that we have two in exactly the same spot. It was pretty much deja vu."
Valentino said two men crashed their bikes in separate accidents at Paradise Drive and Antilles Way at about 8:30 a.m. and 10 a.m.
Both suffered head injuries and were taken to Marin General Hospital.
"We suspect that the two that were up by Antilles were caused by a dip in the road," Valentino said.
"It's a fairly fast turn," he explained. "Once you come to this dip in the road, if you come to the wrong spot there's nowhere to correct."
At about 12:15 p.m., a third accident was reported at Paradise Drive and Teaberry Lane, about three and a half miles from the site of the first two crashes.
In that crash, a woman apparently lost control of her bike after a wheel went off the roadway, Valentino said. She suffered a shoulder injury and was also taken to Marin General.
Valentino said helmets saved the day in all three cases.
"All three of them hit their heads on the pavement," he said. "It would have been much worse if they hadn't been wearing their helmets."
Valentino said firefighters had been expecting a problem or two related to this morning's Tiburon Triathlon, but that none of the three accidents was connected to the event.