The red and white Kona Four Deluxe Nissan Special Edition pedal cycle was stolen between Tuesday 6 and Saturday 10 September 2011.
It is believed that the bike has been seen in the Jennyfields area since it was stolen.
PC Leah Champion, of the Harrogate Safer Neighbourhood Team, said:
I am urging anyone who may have seen the bike since it was stolen or has any information about the person who stole it to contact that police or Crimestoppers as soon as possible.
If you can assist with this investigation please contact PC Leah Champion at Harrogate police station on 0845 60 60 24 7 quoting reference number 12110153875. Or call Crimestoppers anonymously on 0800 555 111.