？
Who'd ever want a bike with squeaky brakes?
Literal
Brake [subj-が] squeak-squeak say bike [like-なんて] wants person exists [reason-わけ]?
キーキーいう (literally 'going squeak-squeak') shows the productive pattern [mimetic]+いう for 'making the sound of X.' なんて adds a dismissive 'something like / a thing like' tone to the preceding noun. 欲しがる is the third-person/observational counterpart of 欲しい: Japanese reserves 欲しい (pure desiderative adjective) for the speaker's own wants, and uses がる-marked forms for observable desires of others. The sentence-final わけ? turns the whole utterance into a rhetorical 'there's no way...?' question.