Brisbane's CityCycle bike hire scheme has cost ratepayers more than $8 million since it was introduced in 2010, figures released by the Quirk council administration show.

But the Labor opposition believed that figure was closer to $20 million and has promised to renegotiate the contract with the scheme's operators, JC Decaux, should its candidate Rod Harding be elected as lord mayor next year.

Brisbane's CityCycle program has come under fire from the Labor opposition. Credit:Harrison Saragossi

A request was made for an interview with Lord Mayor Graham Quirk, but his office instead provided a written response to Fairfax Media's queries from public and active transport chairman Peter Matic.

Cr Matic said CityCycle had cost ratepayers $14.63 million since it started in 2010, which was offset by $6.3 million in revenue.