Written around 2012. Maybe updated sometime.
This is the last in the four part series. Please check out part 1,2,3 if you haven't already. This one is about the luggage set up. I find that using a trailer is preferable because it takes weight off the frame and the bike is more maneuverable. I would recommend the Extrawheel Voyager trailer.
The design is now extremely simple with the panniers attaching onto a lightweight frame. It is good on rougher terrain (its the best option for mountain biking on rocky terrain) and the spring metal fork attachment is also the best of any trailer I have tested.
It is more reliable than the attachment on BOB Yak trailer which uses lynch-pins which are attached by pieces of rubber. I managed to lose one of these the first time I used the trailer. A new way of attaching could be designing quite easily (or modified).
The Yak is extremely strong and sturdy with a steel frame and platform. Its better for carrying larger objects (possibly for non-touring use - I've used mine for carrying wood). I was surprised at how well it worked for light off road use (South West Coast Path) as I was very sceptical beforehand.
However, by nature of its design with the small wheel, its not going to be able to tackle the rockier stuff as well as the Extrawheel with its 26 inch wheel. The carrying space offered by the Yak with its huge bag is fantastic and I found it more convenient to have all my kit in the one bag and then in drybags. It can be easy to forget which pannier you put stuff in - maybe the panniers could be colour coded to indicate their contents?
I used Exped drybags, however, I also used another no-brand bag and this was more durable e.g. one from Decathlon would probably be fine. I used two waterproof Crosso panniers that come with the Extrawheel trailer and two of the Carradice Super Cs. I usually carried food in one of the rear panniers and clothes in the other and then sleeping kit in one trailer pannier and the stove and other utility items in the other.
Check out my kit list post for general information on what to carry. The Tubus Logo rear rack is the strongest for carrying rear panniers. It attaches onto the frame either by bolting it into a rack eyelet or by using the rack mount bracket which I would recommend doing anyway because it reduces the strain on the frame.
I've never used front panniers for various reasons - no need with the trailer, affects bike handling, didn't fit on the forks. I used an Ortlieb bar bag which was incredibly useful. In it I would usually carry objects which it was handy to have quick access to such as a camera. However, even having this on the handlebars affected handling.
For all my trips I strapped a 60 litre Extrawheel drybag on top of the rear pannier rack for holding the tripod, tent poles, roll mat or other long objects in. It protected them from dust and moisture. I strapped it on with a bungee which then created a place to quickly attach other items wedged underneath the bungee,like a jacket for quick access. However, this drybag is something which could likely be dropped to save weight.
On the Mongolia trip I took a decathlon roll-top, drybag-rucksack combo bag which was very useful because I was able to use it to carry all the luggage in on public transport. However, I've heard they don't sell them anymore. I still use this bag daily as it can be rolled down to a small size or carry many things if needed.
That is the end of the series on building the perfect expedition bike. In reality I have described my own experiences and choices and there are many variations and possibilities. Please leave a comment below if there is anything in the series you would like to leave feedback on.