The men’s touring bicycle had been parked and secured in the rear car park behind Ye Olde Whyte Swanne pub and Louth Town Hall.
At some point between 9.30pm and 11pm, the bicycle was stolen. The padlock and chain were also taken.
The bicycle is described as a Dawes Super Galaxy with a green frame, a saddle bag on the rear, 27 gears, and a front and rear light.
If you have any information, call Lincolnshire Police on 101 and quote incident number 491 of October 18.