I rode la Marmotte this year
I rode la Marmotte this year without doing any particular training and got round. I rode a few sportives – Forest of Dean, Gran Fondo Cymru, Archer, Dragon Ride and also Sunday rides of about 80-90 miles fairly regularly also London to Brighton and back (out over Ditchling, back over Devil’s Dyke – thanks Jo!) and then Bristol 12hr solo.
I cracked on Alpe d’Huez but was still walking and talking afterwards.
You’ll need to get used to riding in a group, and also 2 hour climbs ;o)
The real problem with riding the etape is that as a Brit you set off last so you’ll always be chasing the time cut off.