I'm in the process of designing MYOG packs for my growing kids. I've come up with a few ways to make the torso length adjustable, but none are very easy to implement. Anyone have any ideas for me?

Strong velcro strips (ala Osprey packs) or daisy chains. If you're using stays then look at the new zpacks Exo for inspiration.

http://www.youtube.com/watch?v=FuskqsfW7Tg

I use a carbon fiber frame for all my packs. To adjust the torso length I replace or shorten the vertical stays. Replacing a vertical stay only takes a few minutes with my pack design. In the case of a child one could replace the stays with longer ones as the kid grows.

Here's a link so you can see what I mean:

here

Edited by lyrad1 on 01/19/2012 12:38:23 MST.

When I worked at REI I usually recommended people get a Kelty Coyote backpack for kids, especially Scouts looking for an adjustable pack. The shoulder straps run along the stays toward the sides of the pack and are sandwiched between the frame sheet and the back panel. The straps secure in place with Velcro between the back panel and the strap assembly. Something like that would probably give you the most adjustment and longest use out of the pack.

Edited by bobgengeskahn on 01/19/2012 12:51:13 MST.

I've been thinking that the easiest to build would be a (flat)daisy chain up the back and then you could attach the top of the shoulder straps to the daisy chain with plastic zip ties. (I'm picturing a tunnel through the top of the shoulder strap assembly for the zip tie). You might need to add a extra padded tongue to the shoulder straps to go over the bit with the zip tie. Then when the kid grows just replace the zip tie.

Need to know what kind of pack you are designing; mostly:
frame or frameless
type of frame if frame
desired weight range

Thanks.

Edited by scfhome on 01/19/2012 15:49:42 MST.

Thanks, all, for the tips. The pack will built with a sleeve behind the back panel that I will slide a myog frame into, so I anticipate needing a way to adjust straps up and down externally. Right now I'm thinking some type of daisy chain attachment using velcro straps. Still open for ideas of course.

check out how deuter or six moon designs does it on their packs. There are a series of horizontal webbing straps sewn in the center of the backpack. The shoulder straps are actually a single strap that goes around the back of your neck and in the middle of this harness there is a velcro strap that loops around 3-4 of the webbing loops and closes. Seems to carry well (I love my SMD Starlite with this strap arrangement) and my friend loves her Deuter (with very similar strap arrangement). On top of that it seems like it would be pretty easy to make since there really aren't that many components, and it is very easy to adjust on the fly.

Still unclear about type of frame.

Are you are willing to have at least one curved adjustable horizontal cross-bar?

It will help keep the frame's rails, or sidebars, in the position you want for it to function at its best in holding the shape of the 'envelope' and will help keep the pack contents from bulging or poking against the wearer's back.

The adjustment doesn't have to be fancy. It could be just a couple plastic hose or rubbery polymer kite T-fittings that can be moved up as the kids grow. You would not want too tight a fit on rubbery polymer fittings, as they would then not be able to be moved once the lubricant you used installing them dries out. (Mineral spirits work well). The Ts can be cut shorter at the top for easier movement, or bored slightly for a less tight fit. Worst case, you could cut the fittings off and replace them - they are inexpensive - buy some extras. If you are using larger tubes for your frame rails, you might want to look at PVC plumbing T-fittings, for some that fit with just enough friction to stay put until you want to move them. These can be bored also. With larger tubes you could used tiny screws or pop rivets at the outside to hold the fittings in place - not a good idea with tent pole size tubes whose integrity would be destroyed by that.

Then you would create a series of horizontal slots, running directly on top of each other, around shoulder height in the center of the backpanel, reinforced with heavier material bonded and sewn on. In the old days, it was a leather patch. Nowadays it could be a plastic sew-on patch, or even Zpacks 2.92 oz cuben/nylon laminate if you want to get fancy. You can also 11use two such patches, side-by-side, to precisely locate the width between the shoulder straps at their top. The webbing exiting the top of each shoulder strap goes into the slot, under and around the cross-bar, back out through the slot, and is secured with a small buckle, also attached to the top of the strap where the webbing comes out. The excess strap coming out of the buckle can be tucked into the slot to keep it out of the way. You may want to slide a short collar onto the cross bar to keep the straps separated inside the envlope at a predetermined width. Allow enough width for the kids' growing.

As the kids grow, you remove the frame, raise the cross-bar, reinstall it, and reinstall the straps through a higher slot. Voila!

Without knowing more about your frame, that's my best proposal.

Edited later for to add info.

Edited by scfhome on 01/21/2012 10:15:51 MST.