Tire size

One of the questions you have to deal with in building a touring bike is what size of wheels to use. My current bike is a standard road bike, with 700 mm wheels - so my first thought was just to stick with what I know.  Then I opened up the web (often a mistake).  Seems like wheel size brings out quite the collection of "expert" opinion and associated invective. I can't say that either the partisans of 26" wheels or 700 mm wheels were convincing.  The basic argument for smaller wheels (26" - standard mountain bike wheels) is two-fold: (1) for size XX components (e.g. spokes, rim thickness, etc) the smaller wheel is stronger, and (2) in countries that don't have bike shops serving road racers, replacements for tubes, tires and rims for 26" wheels are really common while 700 mm stuff is rarer.  The arguments for 700 mm wheels seem to be mostly that the 26" wheel arguments are bullshit and your mother wears army boots. Actually the main argument for 700 mm wheels seems to be associated with the smoothness of ride over potholes due to the larger diameter - I was thinking a bit about what the actual difference would be in the arc length of either tire and I'm not convinced - I'll agree that a 10" or 14" wheel would feel really different over potholes, but I can't see the difference between the 26" and 700 mm rims being significant compared to the rim width, tire diameter, and inflation pressure.

Then I started reading about the (relatively) new 29'er wheels (which are really 700 mm rims that can handle wider tires) and decided to shut down my computer.

In the end, Surly Bikes came to our rescue - for short people (frames smaller than 56 cm) the Disc Trucker is only designed for 26" wheels. This makes a lot of sense to me, because the larger wheels on smaller frames can lead to an "overlap" problem - where turning the front wheel at low speed puts the tire into the rider's foot if the pedal is all the way forward - not something you really want to happen with fully loaded panniers.  So we'll be using 26" wheels.