christy p said:
which would be better a backpack with /without a frame I know that weight is important What size backpack?
Religious wars have been fought over lesser topics than this!
To expand on the comments from scruffy, I would add that a "frameless" pack can be misleading. Many frameless packs still use a stiffening method (sheets of rigid plastic, sleeping pad, etc.) to enable at least partial transfer of the load to the hips. Absent load transfer, all of the weight is going to be on your shoulders, not your hips. If you pack light enough, that may not be a problem. However, even spartan packers aren't likely to go below 8 lbs of gear (clothing, toiletries, sleepwear, etc.). Add an extra 1.5 to 1.75 lbs for a frameless ultralight pack plus 2 to 3 lbs of food and water, and you're talking about hanging 12+/- lbs off your shoulders for 30+ days, which will either kill you or make you stronger. (At least, it would kill me; my son would be stronger for it.)
There are some really nice frame packs out there in the 3 to 3.5 lb range that do an excellent job of transferring weight to your hips. Yes, they are roughly 2X the weight, but I
personally find the load transference to be a huge improvement, resulting in far less fatigue even though I'm carrying more weight. Therefore, while I personally own true ultralight packs in the 1.0 to 1.5 lb range, which use sleeping pads as the stiffener, I almost always end up back with my 3.5 lb Gregory Z40 because I'm so much more comfortable and less fatigued at the end of a long hike.
The trick here is all about fit, since almost none of the packs are adjustable for different length spines/torsos. This means you have to really test them under load at a shop. For instance, equivalent packs from Osprey and Gregory with equivalent spine measurements, will still fit slightly differently. In my case, the Osprey digs ever so slightly at my hips, but doesn't with my son who wears exactly the same size pack (he has a negligible 1/8 inch difference in spine measurement from me). In both of our cases, a Deuter for the same length spine results in excess weight on our shoulders because we're just at the edge of that size of pack. All the statistics on the Internet can never replace what you'll learn by wearing one around a store for an hour or two with 15 to 20 lbs of load.
As to the question of capacity, 30 to 40 liters should be more than sufficient if you follow the packing advice of the more experienced members on this site. As a side note, methods of measuring pack capacity aren't standardized, and most pack capacity is overstated. Tests by the backpackinglight.com community have shown variations of 5% to 15% are common so you really want to test smaller sizes with the actual gear you will carry because a 30 liter pack from Brand X may actually only hold about 25 liters, whereas Brand Y may be 28 liters.
PAX,
Matt