P-Biel/Solothurn (63km) cycle paths

Touristic route to go to Solothurn from Biel/Bienne; it's good if you want to avoid traffic, but it's really "touristic". On a Sunday sunny afternoon, there are lot of families and kids with their bicycles. Also, direction Solothurn very often it's necessary to be very careful (and stop) to cross main roads. From Solothurn, back to Biel/Bienne, the route is mainly off-road (it's possible to do with a road bike if it's sunny and dry).