The Couzy route offers a nice short climb on the north face of the Aiguille de l'M. The overall rock quality is really good. The route is like all classic routes before the introduction of modern bolt climbing: it follows a logical system of cracks and fissures. You can find several old pitons on the belays and lengths, (luckily) no bolts!
For an experienced climber, it's probably a nice day out when the weather is not stable enough for a long tour. However, it's definately not a beginners route and only suitable if you have alpine knowledge and know how to deal with alpine circumstances.
This page is to give an overview of the route, not to give a complete topoquide, you should buy the topo yourself.
From Plan the Aiguille or the Montenvers station, follow the big high trail between both stations until you arrive under the north face of the Aiguille de l'M.
From there, scramble up the moraine, there are a few undefined traces. Walk in the direction of the spacy storage building, right there you can find the start of the Couzy route.
see the main page for more info.
First of all, a proper topo is always indispensable for alpine climbing. This description is not enough as information and the text below is how I recall the route. However the route is quite logical and probably you won't need the topo at all during the climbing. For the start of the route you should climb some II graded rock, afterwards you'll arrive at a platform where you put on the climbing equipment and start belaying. The first two pitches are easy (IV), first climb straight up and then to the right. The following pitches are around V-V+ with several pitons on the crucial places. The key pitch is a nice pitch with two small overhangs, free climbed around VI, with the aid of the quickdraws a friendly V+/Ao.
After that, follow an obvious fissure to the ridge in 2/3 pitches, graded V. The Couzy route is finished now, but after you traverse 20m in horizontal terrain you can climb in one pitch to the summit. Look for the most logical place to climb it up.
Descent: Descend in one pitch to the horizontal band where the Couzy ends (bolts on the summit). From there, two options, descent the couloir on the west side as described in the Lindsay Griffin topo. However, it is subject to severe rockfall so please be very careful with this option. The second option is to rappel the Couzy itself. The belays are old but solid. The route meanders a little but it's no problem to rappel. You should strenghten the belays when you judge them to weak.
Twin 50m rope, 10 quickdraws, 5-6 friends, rack of nuts, helmet, slinges, small ropes to reinforce belays. Pegs and hammer are not necessary.
see for more pictures and info the main page about the Aiguille de L'M,