Just starting to plan for doing the La Marmotte in France next year - 174km
taking in the col du Glandon, col du Galiber and finishing with the climb up
to Alpe d'Huez. Currently I have a Shimano Ultegra groupset with a 53/39
octalink chainset. My lowest geared cassette is a 12-27 giving a bottom gear
of 37.7. Having studied the race profile I am thinking about taking
something a bit lower just to be on the safe side. Alpe d'Huez with 160km
(100 miles) in my legs looks a bit daunting.
My initial thoughts are either a triple 52/42/30 which would get me down to
29 with my 12-27 or sticking with the 53/39 and going for a 12-34 cassette
to give 29.9.
I would welcome any advice on the most economical way to go. Mostly this
comes down to what will work with what. E.g. will a triple fit on my current
bottom bracket. Can I cut the cost by using a 105 or perhaps a lower spec (I
doubt if I'll use the kit for more than one or two of these adventures).
Will my current Ultegra front mech shift a triple. What rear mech can I get
to shift a 12-34 and if not Ultegra will it be compatible with my Ultegra
STIs etc