Legal Question in Business Law in California

Gosh, who knows? There is an implied warranty in most sales, but it's pretty limited as to what is covered. You may, hopefully, also have an express (written) warrantry. There is no general, one-size-fits-all, right to return purchased merchandise. You may have just acquired a bike, like it or not. Why do you want to return it? Do you want to return it for credit on another purchase, or for a full cash refund? Do you have a written contract? Does the store have a policy? Is the policy made clear by signs in the store or otherwise?

There is no legal 'right' to return things. Choose your purchases wisely. IF there is a legitimate defect or other valid reason to return under warranty, then you could file a small claims court case and try to convince the judge you are entitled to refund.