https://swhs.home.xs4all.nl/fiets/index_en.html
By lacing my saddle while it was yet new and un-sagged my Swift will never sag.
It cannot sag because its shallow sides cannot now splay outwardly.
Now, if experience proves me wrong, I will say so in an edit to this posting.
But Wouter and some thought have convinced me that simple things really are as they appear. I will avoid riding it wet, and carry the rain cover for it always, but as it is dry, and laced with just two zip ties through holes simply made with a sharp, slender awl, this Swift cannot ever sag:
View attachment 23595
View attachment 23596
When first ridden, I had soaked the new saddle in tepid water for about 15 minutes to allow it to conform quickly with my sit bones, which it did. But the sides also splayed out and the top stretched and sagged. I came home after a 5 mile ride, bandaged the saddle with an elastic wrap while it dried, and thought. I removed the sag by tightening the adjuster bolt. And the next day I did what had to be done: poked holes with the awl. And while I could have used shoelace, I had none. I had zip ties. And they are super easy to install and tension just-so, and so I think I will retain them.
The Swift has very shallow sides. Which look nice. But if the Swift saddle gets wet the leather becomes stretchable and with such shallow sides, those short sides give very little I-beam support to the top, and worse, they splay outwardly, even more destroying the support for the top.
Brooks saddles such as the B17 always have deep sides, presumably to always provide support for the top against hummocking.