tourer versus mountain bike
I’m trying to decide what type of bike to get for a cycle ride across china and central Asia. I'm going to be heavy loaded, with front and back panniers and riding across a variety of terrains, from corrugated and rutted tracks, to packed dirt roads covered in sand, to the finest metalled European roads. I have no idea what to buy, I'm paranoid about breaking stuff (so I’m going for a weldable steel frame- i think that would be more comfortable too), and about not being able to get parts. Any help would be heaven sent!
I was thinking:
Should i get...
a) A steel touring bike with 700 cc wheels (but quite chunky tyres)
This seems to have the advantage of having long chain stays, and being more comfortable, and possibly more efficient (is this right, would it be less tiring to ride than other bicycles?). I'll be riding several thousand miles, so i want something comfortable.
The big disadvantage is the wheels: apparently you can’t get replacements in the middle of nowhere, so I’d have to carry spokes and tyres and inners all the way with me, and if it went wrong, I’d have to get parts dispatched to me. Should i worry about parts, or just cross that bridge when i come to it? Will stuff break?
The other disadvantage is that while it would be easier to ride on good surfaces, i worry that it wouldn't be responsive enough on trickier terrain.
b) A steel mountain bike with 26" wheels
I just worry that'd id feel really cramped, and that I’d find myself kicking my panniers all the time, and that it would feel like a real slog to ride on the metalled roads (is this my imagination, will small wheels really make that much difference?). The advantage is that I’d be able to get parts for it anywhere.
If so... can anyone recommend a good steel mountain bike frame with braze ons for panniers?
c) Something i haven't yet thought of
Someone at work mentioned a cyclo cross bike (i think he was wrong) but maybe that's good idea... any ideas welcome!
I'd really appreciate any advice on this, even if it's just "stop worrying and buy something!"