The Cauberg has a maximum gradient of 12%, la Redoute 17% and the Mur de Huy a whopping 26%.
With a total elevation gain of 1,347 metres over its 32.4km and a maximum gradient of 18%, it's a terrifying prospect, but I'm far enough in that I can't turn back.
One of the world's steepest is the Katoomba Scenic Railway in New South Wales, Australia (info.mountains.net.au/rail/scenic.htm), which has a maximum gradient of 52 degrees from the horizontal.
The Koppenberg hits the riders with a maximum gradient of 22%, forcing all but the strongest to climb off their bike and run up the cobbles as if the Ronde is nothing but the hardest cyclocross race in the world.
3.48pm BST 3.47pm: Apologies, it's the third of four climbs of the day: Santa Maria de Criptis, a third category climb of 3.9 kilometres with a maximum gradient of 14%.
ALPE D'HUEZ YOU SAY > ALP DOOOO – EZ (rhymes with fez) ALTITUDE > 1,850m HEIGHT GAIN > 1,150m AVERAGE GRADIENT > 8% MAXIMUM GRADIENT > 13% LENGTH > 14.5km LOCATION > French Alps The Alpe d'Huez is probably the most famous mountain climb in cycling and certainly the most glamorous in the Tour de France, where it was the scene of the first ever mountaintop finish in the race.
ANGLIRU YOU SAY > ANG (rhymes with hang) – LEE – ROO ALTITUDE > 1,573m HEIGHT GAIN > 1,245m AVERAGE GRADIENT > 10% MAXIMUM GRADIENT > 24% LENGTH > 12.2km LOCATION > Picos de Europa, Spain The Alpe d'Huez might be more famous, but the Angliru is one of the hardest climbs ever used in cycling where it forms part of the Vuelta a España.
He placed great emphasis on two features: (1) maintaining a level roadway with a maximum gradient of 1 in 30 and (2) building a stone surface capable of carrying the heaviest anticipated loads.
The stage was the toughest of this year's race, with a 136-mile trek from Caldes culminating in a 14-mile ascent up the snow-covered Stelvio, which has a maximum gradient of 12 percent.
However, the railway's lower potential maximum gradient requires deeper cutslopes.
Figure 8 Local edge detection and maximum gradient variation.
