The calculated distance (air line) between Rheda-Wiedenbrück and Bielefeld is approximately 16 miles respectively 26 kilometers.
By car or train, the actual journey to Bielefeld is certainly longer, as only the direct route (as the crow flies) between Rheda-Wiedenbrück and Bielefeld has been calculated here.
Air line (approximately)
26 kilometers
14 nautical miles