Francine Paula Pascal was an American author best known for her Sweet Valley series of young adult novels. Sweet Valley High, the backbone of the collection, was made into a television series, which led to several spin-offs, including The Unicorn Club and Sweet Valley University. Although most of these books were published in the 1980s and 1990s, they remained so popular that several titles were re-released decades later.
11-year-old Ari Jacobs is the youngest in her family, which she hates. She gets picked on by her sister and brother, and inherits all their hand-me-downs.
Liz, her older sister, was given a beautiful and expensive 10-speed bike for her birthday. She keeps it in the garage of their apartment building, but is very protective of it and double locks it, covers it, and checks on it every night.
Rhona is a girl in Ari's class, whom Ari considers her best friend (although it is only one-sided). Rhona bullies Ari into letting her use Liz's bike for the school bike race the following day.
Ari gets up early the next day and sneaks down to the garage. She takes the bike to the park and waits for Rhona to meet her. She spots a homeless man getting harassed by some boys, and leaves the bike to go help him. She is able to retrieve the man's hat for him and they sit down together for a minute. When she gets up to leave, she has the sickening realization that Liz's bike has been stolen. She searches the entire park for the boys and the bike, but they are long gone.
Seems to be the first work by Pascal and is involving typically a teenage girl navigating the pitfalls of growing up and finding her identity in life. Reasonable and the template for what she would later turn into a franchise.