The calculated distance (air line) between Saint-Imier and Biel/Bienne is approximately 12 miles respectively 19 kilometers.
By car or train, the actual journey to Biel/Bienne is certainly longer, as only the direct route (as the crow flies) between Saint-Imier and Biel/Bienne has been calculated here.
Air line (approximately)
19 kilometers
10 nautical miles