It’s false that cyclists routinely ride on the sidewalk in Paris, let alone at full speed. They ride on the road (car and bus lanes) and in bike lanes. It’s true, however, that on some very popular bike routes (rue de Rivoli, boulevard Saint-Michel/Sébastopol), there are enough cyclists that don’t stop at lights that pedestrians can’t easily safely cross. This is a solvable issue that’s independent from the modal share or infrastructure.