On the boulder of Bicarburation, at the end of a quarry, under the plateau, to the left of de La Route des Gorges de Franchard, in direction of La Gorge du Houx. Sitstart at the right pillar of the bivouac as for Bloc l'Éponge and continue in Bicarburation.
NB: this is the original line in this roof, many variants have now been climbed and all kinds of new combinations are possible; we've decided not to publish all of these and stick to the most logical lines.