The calculated distance (air line) between Arrasate / Mondragón and Bilbao is approximately 26 miles respectively 42 kilometers.
By car or train, the actual journey to Bilbao is certainly longer, as only the direct route (as the crow flies) between Arrasate / Mondragón and Bilbao has been calculated here.
Air line (approximately)
42 kilometers
22 nautical miles