The grey Forme bike was snatched from the Piccadilly area on Monday (February 3) at about 11.45am.
North Yorkshire Police said the bike “had been attached to some railings” near Infinity Motorcycles before it was taken.
The force urges anyone with information about the theft, or who knows where the bike is, to get in touch.
Those with information that could help the investigation are asked to email nabiel.galab@northyorkshire.police.uk or phone 101, select option two and ask for Nabiel Galab.
Crimestoppers can be contacted anonymously on 0800 555 111 or via its website.
Quote reference number 12250020813 when passing on information.
