Carbon fiber bikes weighing about seventeen pounds have been discussed and used for touring.

TDF riders often use bikes weighing about fifteen pounds. These bikes usually hold up for thousands of miles of hard, fast riding. The riders have the strength, skill, and motivation to push them very hard. The bikes are stressed much more than a reasonably gentle light weight or ultralight touring cyclist's bike.

But these TDF bikes' weights are artificially high, because the governing organisation (the UCI) drew a line years ago, and disallowed bikes lighter than 6.8 kilograms. With newer materials and technologies, this could be safely reduced -- and there have been many calls for this.

In other words, even lighter bikes can be plenty strong for (reasonably gentle) ultralight (UL) and sub-ultralight (SUL) touring.

The question here is, How light can one go? What are the (safe) limits, while still maintaining sufficient performance and reliability?

And what components might be used? And could the costs be kept to a reasonable level?

(I once came across a website by a German guy and his son. Their enviable hobby was building bikes that were as light as possible. And they succeeded in building several mountain bikes that were down around ten pounds, and road bikes that were down around six or seven pounds.)

If they handle well and hold up, then why not -- this could make for some light touring. Some of us enjoy the lighter bikes, and riding them, in the mountains especially, with lighter loads.