The lightest bikes would be 26 inch audax bikes with 50 mm wide tyres or 650B audax bikes with 42 mm tyres (650B is an old French tyre size that is becoming increasingly popular again, though not yet very much in the UK). If you go to a custom builder you can have them from 11 or perhaps more realistically 12 kg, including rear rack and mudguards. A much cheaper alternative would be to get a second hand steel 700c road bike and do a so called 650B conversion with 42mm Grandbois Hetre tyres (New wheels and new brakes is all you will need). If you can find a bike with enough clearance for the Hetres, this would be a cheap, comfortable and very classy option. I would also keep the drop bars. Finally, I would fit a Thudbuster ST seatpost. These are the best you can find, and are far more comfortable than sprung saddles. You need a bit of seatpost length, but if you have that, they are great. I think they are ugly, but I was very happy to use one on a part off road tour in Norway last summer (I have a bad back).
With respect to the current bike, I would look for wide, flexible and light tyres such as the 50 mm Schwalbe Kojak (unless you want to ride trails, in which case use light modern mtb tyres or Marathon Extremes for serious off road touring). Use ultralight tubes in them and you will have saved more weight. Don't waste money on a new bike that may be 2-3 kg lighter, at the very best.
On balance, it is much easier and cheaper, however, to reduce the weight of the luggage (and of your own body) than to reduce the weight of a bike. Once you are back in shape, think about a custom bike if you still think you need and deserve something lighter, and when you know what kind of touring you will do (so you can get the bike that is just right). Or get a 650B conversion for road use, and use your slightly lightened existing mtb for the trails.
It is no problem at all to tour with camping luggage that will fit in just two rear panniers (did that, even in Norway). A total camping luggage weight of 15 kg for western European conditions is quite easy, and 12 kg is possible. Below that, you will have to compromise on comfort.
Willem
With respect to the current bike, I would look for wide, flexible and light tyres such as the 50 mm Schwalbe Kojak (unless you want to ride trails, in which case use light modern mtb tyres or Marathon Extremes for serious off road touring). Use ultralight tubes in them and you will have saved more weight. Don't waste money on a new bike that may be 2-3 kg lighter, at the very best.
On balance, it is much easier and cheaper, however, to reduce the weight of the luggage (and of your own body) than to reduce the weight of a bike. Once you are back in shape, think about a custom bike if you still think you need and deserve something lighter, and when you know what kind of touring you will do (so you can get the bike that is just right). Or get a 650B conversion for road use, and use your slightly lightened existing mtb for the trails.
It is no problem at all to tour with camping luggage that will fit in just two rear panniers (did that, even in Norway). A total camping luggage weight of 15 kg for western European conditions is quite easy, and 12 kg is possible. Below that, you will have to compromise on comfort.
Willem
