Available in a range of sizes, Carradice's Longflap is the big daddy of saddlebags, expanding to a capacious 24l of stowage space.
As the name suggests, an extra flap can be unfurled, allowing bulky kit to be stowed under the lid. There are two side pockets to fit inner tubes and spares, and a protective patch on the underside so mud and muck can be wiped off easily. Build quality is excellent and the bag wears in like your favourite Brooks saddle.
The fibres of the cotton duck material expand when wet to provide almost complete waterproofing, though I'd still recommend a thin, canoe bag liner for prolonged heavy rain. In the unlikely event that you manage to rip it, it's easy to repair with old fashioned cotton and thread. Leather straps aren't as quick as buckles but are ultimately more reliable, and more in keeping with the traditional looks.
There's a loop to attach a rear LED and a reflective patch too. To stop the bag rubbing against your legs, you'll also need the SQR fitting (£24.95), which is strong and robust, or the Bagman pictured (£36.95) which is more elegant and better suited to road riding. Both are rated to 10kg. The Longflap is fairly deep (23cm), so won't fit on smaller frames – the shallower Nelson or Barley would be better.
Saddlebags seem to have fallen out of fashion, yet provide the perfect means to carry enough kit for a lightweight tour, especially one as big as this.
What's more, positioning the load centrally under the saddle has less impact on handling than panniers, and you can mount a saddlebag to pretty much any road bike (note that we'd recommend swapping out the seatpost for an aluminium one if yours is carbon).