Read The Pacific Crest Trail Hiker's Handbook by Ray Jardine, I read the first edition in the 90s, may be different title now. Summary: He hiked the Appalachian trail with typical pack of mega weight, I think over 60 lbs, decided there was a better way. Ray was a rocket payload engineer. Lower the payload, you need less fuel. Less fuel, the whole rocket can be lighter. That lowers fuel requirements even more.

He ended up with a simple pack, I think 8 lbs for that and contents, not counting food and water. With less weight, he could hike in running shoes, much lighter, and cover far more distance in a day, which also meant less food to carry between resupply boxes at mailed intervals. He could also descend quickly from high altitude on the Pac Trail if needed, so less critical to carry heavier outerwear.

The big 3 are:
- backpack: sewn himself, one compartment with only shoulder straps.
- shelter: he used a simple tarp.
- sleeping bag: he used a simple quilt he made himself.

I went a la cart, adopting some of his practices:
- 3000 cubic inch pack, with shoulder straps and good hip belt, about 3 lbs, less than half of the biggies.
- rectangular dome tent, 2 person, only a pound heavier than 1-person and way better to sit out rain in, room for gear inside, freestanding so easy to set up on solid rock if needed, easy to move, 5 lbs I think.
- sleeping bag depending on the weather, fleece pants and jacket for more warmth if needed, and can use on trail, perhaps 4 lbs for all.

That's 12 lbs. Add stove and fuel, food, water, oh and I like adjustable height hiking poles, poles allow using my arms to climb too, way more efficient and faster, easier on knees. And these days there are tents and lean-to's that use them instead of tent poles. But I also require bug screens, not open. I also need a sleep mat or my shoulders and hips ache in the morning. So I think I'm below 20 lbs on the pack with food and water, but I haven't thru-hiked yet.

So apply the above to bike touring:

No pack, but simple panniers with ultralight ditty bags may be lighter and tougher than more complex panniers.

Compactness of stuffed sleeping bag is as important as weight. Down has traditionally been best there, but it's useless if wet and slow to dry. I think there may be better synthetic substitutes these days, that don't loose their loft as much from constant tight stuffing, and dry out easier each day from just sleep moisture.

Shelter: That varies a ton based on where you are touring. I may want to be able to fold my bike and bring inside the tent for anti-theft. I traded out my old tent for one with vestibules on both sides, had terrible hot weather ventilation versus open fly on my old one, plus heavier, I got my old tent back from my brother, gave him a car-camping tent, better suited to him.

It's about a philosphy, questions to ask. Oh and I also dried my own food, rather than the expensive freeze-dried.