Cotacol nr 62, a tough slope of 1600m and 9.7% average. If you want to climb a bit less steep, 2 recommendations: -Côte d'Oneux 2800m and 6.9% a bit more …
Very nice climb in the shade with good road surface. On paper quite hard, but I found it quite bearable. Cotacol nr 297, length of 2100m and average 8.4%.