Originally Posted by invisiblehand
Actually, the Rivendell Saluki that your link leads to takes 650B tires, not 26". 650B (584 mm tire bead diameter) is a size somewhere betwen the 700C (622mm tire bead diameter) that is common on road bikes and the 26" (559 mm tire bead diameter) that is common on mountain bikes. Whatever the merits or shortcomings of this tire size, it is going to be difficult to find tires in this size.
Rivendell does make the Atlantis touring bike, which comes with 26" wheels in the smaller frame sizes, up to 56 cm seat tube length. My own Rivendell has a 58 cm frame and 26" wheels, and the appearance takes a little getting used to.
You might find a few more people with firsthand knowledge of Thorn bikes on the Cycling Plus forums,
www.cyclingplus.co.uk/forum/