Light-weight backpack (50ltr-ish)…

The obvious answer for NZ of course is one of the Macpac Ascents, but you're probably looking at almost 4lbs. That's NZ lightweight, not US lightweight.

Thanks for that. I actually have a Macpac Traverse at the moment which is a great pack. However, I tend to overpack due to its size and end up with one hell of a load…

Does the pack you mention have a removable frame to allow it to be folded small?

I'm not sure about the New Pursuit 50 tho. Check them out here.

http://www.macpac.co.nz/catalogue/category/d4205a90-eac6-464a-a2b4-4f5fba7860ab/NZ

Rod

I recommned one of several possibilities from CiloGear.com. A small but growing cottage maker from the East US.
I own two CiloGear packs including the 45 Liter WorkSack, it starts life as a fully-featured backpacking pack with external straps, lid, belt, internal plastic frame and frame pad, etc; yet strips down into various combinations, all external straps, the lid, the waist belt, the frame, the frame pad, etc. all come off in seconds.
If you want, strip it all the way down to a 700 gram summit-sack with the original shoulder straps, still 45 liters. Thats the configuration I use for short hikes to the crag with a rack, rope and essentials.

Most versitile pack I've owned, but they are not for everybody. Straps are not as comfortable as the gold standard of comfort, the Granite Gear UL series (but those dont have removable frames!)

Amazingly, with the frame out, it can be stuffed and then zipped up into its own LID; hows that for storing on your bike?

If you can stand more weight, the Black Diamond Predators also strip way down, but are heavier.

Search the forums for "predator" to see my earlier comparison of cilo vs. BD.

(my second CiloGear is the "Schoolbag" which is actually a very well thought out 30 liter clam-shell bag with many of the technical features of its big brothers, such as removable sit pad, compression straps, even a crampon pouch!)

Thanks Brett, I'm going to research those two thoroughly. I like the look of them both… And the former sounds very portable.