Mayor Boris Johnson said the buses were "much-loathed vehicles"
It may not be possible to scrap bendy buses from London before 2015 due to contracts, Mayor Boris Johnson said.
Removing the "much-loathed vehicles" was one of Mr Johnson's key pledges during the mayoral election last year.
The mayor's office said many would be phased out by 2012 when contracts ended, but some may remain operational.
This was due to a deal by the previous mayor which gave bus companies the right to a two-year automatic extension of contract, the mayor's office said.
Of the total nine bendy bus routes, contracts for five will expire by 2011, the contract on the sixth route will expire in early 2012.
The contracts for the three remaining routes end in 2011 and 2013 but because of the automatic extension deal by former Mayor Ken Livingstone's administration the buses on those routes could potentially operate until 2015.
This means that contracts for bendy buses plying on four routes will not come under review until after the next mayoral elections in 2012.
It is "most cost effective" to let the contracts expire rather than to breach them and compensate the bus companies, the mayor's office said.
Mr Johnson, said: "The fact that the bus companies are starting to sell off these beasts of the road shows that our promise to rid London of the much-loathed vehicles is being realised."
Last October critics of the plan said scrapping bendy buses from London would cost an additional £60m.