The calculated distance (air line) between Frenštát pod Radhoštěm and Liberec is approximately 163 miles respectively 262 kilometers.
By car or train, the actual journey to Liberec is certainly longer, as only the direct route (as the crow flies) between Frenštát pod Radhoštěm and Liberec has been calculated here.
Air line (approximately)
262 kilometers
142 nautical miles