One change at Köln Hbf separates RB25 from Cologne Bonn Airport
RB25 runs as the Oberbergische Bahn between Köln Hbf and towns like Gummersbach, Marienheide and Meinerzhagen, but it does not start at Cologne Bonn Airport (CGN). From Terminals 1 or 2 you first ride S13, S19 or a Regional‑Express about 15 minutes to Köln Hauptbahnhof, then change to RB25 for the onward leg into the Oberberg region.
Trains on RB25 typically run every 30 or 60 minutes during the day, with some gaps in the late evening after around 22:00 depending on the section of the line. A single DB ticket from CGN to, say, Gummersbach usually prices between €10 and €18 if bought as a standard local fare, covering both the airport–Köln Hbf segment and the RB25 part on one itinerary.
RB25 uses standard regional train stock with 2nd class only, no 1st class cars, and no restaurant car. Regulars report limited luggage racks on these units, so suitcases over 70 cm often end up in the door area or between seats, which gets awkward on a busy run between Köln Hbf and the closer suburbs like Rösrath or Overath.
Overcrowding on RB25 is most common in weekday rush hours roughly 07:00–09:00 and 16:00–18:30 between Cologne and the nearer stops. Commuters on rail forums also complain about occasional “Kurzzüge” (short trains) and delays of 10–20 minutes, which is why they avoid planning a flight check‑in around the very last usable RB25 from their town.
Regulars often pull live data from the DB Navigator app before leaving home and sometimes choose Regional‑Express lines like RE7 or RE1 to Köln Hbf instead of RB25 if those show better punctuality that day. Some also deliberately arrive at CGN 90–120 minutes earlier than the airline’s minimum, padding their schedule in case the RB25 segment from places like Gummersbach or Engelskirchen runs late.
Watch out for the change at Köln Hbf: platforms for S‑Bahn from CGN (often Gleis 10/11) and RB25 (commonly Gleis 1–9) are in the same station but require a short walk and stairs or lifts. Build a 10–15 minute buffer for the transfer, and in bad weather or peak times, simply take an earlier RB25 and have coffee at the airport before security.