In which part of Rumble Fish does the climax occur?

The climax to the Susan E. Hinton novel, Rumble Fish, occurs near the end of the story in Chapter Eleven. After the two brothers meet up at the pet shop earlier in the day, Rusty-James realizes that The Motorcycle Boy is casing the store. They return later that night but not to rob the store; instead The Motorcycle Boy frees all of the animals and takes the Siamese fighting fish--the "rumble fish"--to free them into the river. But he doesn't make it: He is shot dead by Officer Patterson, and the fish die, too. Because of his recent head injury, Rusty-James realizes that he is now color blind--like The Motorcycle Boy--and he is arrested and sent to the juvenile reformatory school.

Where do the first and last chapters of Rumble Fish take place?

The book Rumble Fish by S.E. Hinton begins and ends in the same place and at the same time.  The book opens with Rusty running into an old friend, Steve Hays, five or six years after the main events of the book take place.  The physical location is a beach.  The two men get to talking, but inevitably their past lives come up.  Chapter Two is a flashback and tells Rusty's story, starting five or six years before the present. Rusty's flashback story ends in Chapter 11. In Chapter 12, readers are placed back into the present, with the men talking on the beach.  Steve explains why he left, and then he invites Rusty to dinner.  Rusty politely refuses, because he does not want to be around Steve.  Steve is a reminder of the awful past.