Two bikes were stolen in a shed burglary on Barmoor Bank near Hepscott.
The incident took place between 6pm on Sunday and 8.30pm on Tuesday.
One of the bikes is a 2013 black Merida Speedster – a hybrid mountain bike with bar ends on the handlebars and a small saddle bag under the back seat containing a spare tyre with orange stripes on the crossbar.
It has a mini pump attached to the frame and a Cateye trip computer on the handlebars.
Inquiries are on-going and any witnesses are asked to contact Northumbria Police on 101, extension 69191, quoting reference 231 070715, or email firstname.lastname@example.org.
Alternatively, call Crimestoppers anonymously on 0800 555111.