The calculated distance (air line) between Gerolstein and Bochum-Hordel is approximately 91 miles respectively 147 kilometers.
By car or train, the actual journey to Bochum-Hordel is certainly longer, as only the direct route (as the crow flies) between Gerolstein and Bochum-Hordel has been calculated here.
Air line (approximately)
147 kilometers
79 nautical miles