The Oberbergische Bahn (RB 25) is a Regionalbahn rail service running between Cologne Hansaring and Lüdenscheid in the German state of North Rhine-Westphalia (NRW).

Oliver Wittke, the former NRW transport minister, turned down a proposal to reactivate the entire section in 2005.

[3] The section of the Volme Valley Railway between Meinerzhagen and Lüdenscheid-Brügge was finally reactivated at the timetable change in December 2017.

In March 2011, the Nahverkehr Westfalen-Lippe (Westphalia-Lippe Regional Transport) awarded operations of the Cologne diesel network (Kölner Dieselnetz) to DB Regio Rheinland from December 2013 for 20 years.

This contract requires the following actions on the Oberbergische network to be undertaken: Alstom Coradia LINT 54 and 81 railcars are used for the service.