Julien,
I believe Paul has asked the key question here...
Why does your Nomad weigh 20kg?
Speaking for myself, my own Nomad Mk2 weighs 20kg because of how I have it outfitted compared to my less heavy-duty, more road-oriented steel-frame tourers, which tend to spot-in at about 14.5kg.
The difference for me is in the component and accessory weight...
• Rohloff hub
• Wider, longer mudguards
• Fatter, more robust tires and tubes (big contributor)
• Ryde Andra 30 rims (big contributor compared to, say, Mavic MA-2 on my randonneur bike)
• Bottles and cages for carrying 6.5l on the bike
• 2 Accessory T-bars...and the accessories for them, like my handlebar bag mount
• Heavier, more robust racks
• Thudbuster LT suspension seatpost
• SON dynamo hub and related charging system and full dyno- and battery lighting
• GPS and mount
• Frame lock and cable or chain (heavy!)
• Chainring bash guard
• etc, etc, etc.
It all adds up! it is all "worth it" to me as these things make the bike more pleasurable to ride and better suited to purpose as a true expedition touring bike for me...when I need "heavy lifting" capability for hauling 26.5l of water between sources for desert travel and for solo, self-supported touring with the additions of camping kit, food and fuel for 3 weeks at a time.
When I need to carry less or go on tours where I can readily resupply I take one of my lighter, less-robust bikes, as the extra sturdiness and cargo capacity are not needed and would only be a hindrance. For me, it is horses for courses and nothing in my fleet matches my whole Nomad for what it can do. Unfortunately, that comes at a price -- it is heavier as I have it equipped and as needed to do the job. The same bike with fewer accessories and components chosen for lighter duty/less weight might very well weigh about 16kg, about the same as my steel Enduro-Allroad bike with derailleur drivetrain. I agree with Paul; the frame weight is the least of the difference.
My lightest camp-touring setup requires only a Carradice Camper Longflap weighing 6.41kg that allows me to sleep warm, dry and comfortable, dine on hot food, accommodates rain and cold clothing and a change of riding clothes and attaches to even my lightest bike. See...
http://thorncyclesforum.co.uk/index.php?topic=11787.msg85858#msg85858Agreed, less weight makes for a more pleasurable tour and ride but isn't suited for all rides!
Best, Dan.