The blue bike was stolen from Parthian Avenue in Boston on Tuesday, September 14.
The man is described as white, stocky build, with a tattoo on his neck, and short dark hair. He was wearing a blue top and grey trousers.
If you have any information which could help their investigation, call 101, quoting crime number 21000536027, email [email protected] putting the crime number in the subject line.
or contact Crimestoppers anonymously on 0800 555111.