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