Gary Soto's short story "The Bike" is a first person narrative. The narrator, a five year old, is telling about a bicycle ride onto Sarah Street (a street named off-limits by his mother). The narrator tells readers about a few of his mother's thoughts (ones which are assumed to be old wives' tales or warnings). She tells him pointing at a rainbow will cause freckles. He points at them, apprehensively. As no freckles raise on his skin, the narrator questions some of his mother's ideas.
Later, as the narrator is venturing out upon his bike, he recalls another piece of information of his mother's: hungry dogs with red eyes live on the street and bite little children with hardened throats (made hard by bone). Questioning his mother's warning, the narrator ventures onto Sarah Street. He finds nothing out of the ordinary, and he even tries to show off for another boy on a tricycle. He allows the boy to ride over his legs with the tricycle which ends up injuring the narrator (but he acts as if it does not hurt).
Wounded ankle and spirit, the narrator decides to go home. As he turns the corner, a dog barks. Frightened, the narrator's pant leg becomes caught in the chain of his bike. The narrator falls to the ground. As he comes around the corner, the narrator's mother sees him. She is carrying a belt (in order to punish the boy). The story ends with the narrator taking complete blame for the injury and punishment.
A theme is the central idea within a text. In regards to this text, one could argue that the theme is "mother knows best" (a colloquial saying which refers to the "fact" that parents know what is best for their children--typically used to point out the irony behind a child doing something, getting hurt, and the parent saying "I told you so"). The theme could also be knowledge or lack of knowledge (in regards to the parent knowing about limitations (knowledge) and children testing the limitations (lack of knowledge)). Therefore, you are correct in stating that the theme revolves around listening to one's parents.