"The world is a darker place without her," said Heather Grimm, 30.
Diana Hersevoort, 58, and her husband were riding north on Foothill Road, near Golden Eagle Way, at about 1 p.m. when the two were hit by a car, according to police. Hersevoort was thrown from her bicycle and pronounced dead at the scene. Her husband Joe was taken to a hospital where he was treated for minor injuries and released.
The car, a 2004 silver Dodge Neon, was driven by an 18-year-old Pleasanton man who was also heading north, police said. The 18-year-old stopped at the scene and answered police questions but did not give a statement, police Sgt. Robert Leong said.
The driver has not been arrested, and the cause of the collision is under investigation.
Leong said preliminary information indicates that Hersevoort and her husband were riding single-file in the bike lane on the side of the roadway when they were hit.
He said several witnesses have contacted police.
"If we have enough to pursue a charge we will forward it" to the Alameda County District Attorney's Office, Leong said.
Grimm described her mother Tuesday as an animal lover and a "bright, loving person."
Her father sustained a broken leg.
"Physically, he's OK," Grimm said in a phone interview Tuesday from her family's home in Dublin.
She said she hopes the police investigation continues and that the 18-year-old is prosecuted. Grimm said it would help bring closure to the family.
"But anything that can be done now will not benefit my mother," she said. "What was taken cannot be replaced."
The bicycle ride was a weekly tradition of the couple, who rode together in various parts of the Tri-Valley region, Grimm said. They had been together for 35 years.
She said a private celebration of Hersevoort's life is being planned -- and will take place outdoors because her mother loved nature.
"She was a lover of animals and flowers," Grimm said.
Hersevoort was also a fan of tie-dyed clothing, something Grimm hopes people will wear to her memorial. No date has been set.
She was a stay-at-home mom to Grimm and her older sister and was a proud grandmother to Grimm's 7-year-old son and 2-year-old daughter, Grimm said.
Grimm said her mother loved animals, and that growing up, their house was a "zoo" with many cats and dogs. The couple still has two cats and three dogs at their Dublin home.
Grimm said the local community and her extended family are providing support.
A high school friend of her mother's stopped by with five bags of groceries after the accident, she said.