They were taken from a securely locked shed at a property on Hamilton Avenue in the town, between 8am and 4.20pm on Wednesday 19 September 2012.
The thieves stole a black Specialized mountain bike as well as a red Scott and red Avanti Corsa, which is a unique New Zealand model, road bikes. The three bikes have a total value of around £6,000.
PC David Minto, of Harrogate Safer Neighbourhood Team, said:
If you have been offered any of the these bicycles or can help to identify the people who stole them, I urge you to contact the police or Crimestoppers straight away.
Anyone who can assist with this investigation is asked to contact Harrogate police on 101, choose option 2 and ask for David Minto. Alternatively, information can be emailed to firstname.lastname@example.org quoting reference number 12120157179.