The calculated distance (air line) between Bochum-Hordel and Troisdorf is approximately 48 miles respectively 77 kilometers.
By car or train, the actual journey to Troisdorf is certainly longer, as only the direct route (as the crow flies) between Bochum-Hordel and Troisdorf has been calculated here.
Air line (approximately)
77 kilometers
42 nautical miles