[pct-l] 1977 Thruhike disqualified. Go back and do it again.

[reynolds@iLAN.com (Reynolds, WT)]

A Yoke shoulder suspension system is typically used on an upscale internal
frame pack. The shoulder straps proceed over the shoulders and down the back
meeting in the center of the backpack creating a "Y", hence Yoke system.
Usually the exact location on the backpack where the yoke meets is
adjustable since, with most internal frame packs, the relationship of the
pack bag to the waist belt is fixed. Moving the Y [the location where the
two shoulder straps meet] up lengthens the effective length of the pack
while moving it down shortens the effective length. Understanding the theory
of carrying a load, one BIG benefit of the Yoke system is that it allows
salesmen to sell packs that don't really fit. Lenghting the pack length will
allow the pack to be worn by a hiker who is too tall but the load will be
too low. A real benefit of the Yoke system, however, is that the shoulder
straps are in contact with the hikers body over both the front and back of
the shoulders. This makes the pack feel like it is more "connected" to the
body, a condition which many hikers like, [at least initially when they try
on the pack before buying it] and does in fact add a modicum of control of
the load [most of the load control attributed to internal frame packs comes
from their lower center of gravity. This is why internal packs are better
for off trail scrambling but inferior for on trail walking]. Obviously the
problem with the Yoke approach is that there is nothing to prevent the pack
from pulling back on top and creating pressure on the shoulders when it
does. To overcome this, pack manufacturers add stabilizing straps that run
from the shoulder straps to the top of the pack bag. These stabilizing
straps should run upward from the shoulder at a 45 degree angle to the bpack
bag. This is to avoid shoulder compresson when the pack pulls backward.

With the Kelty Tioga SOME pack length adjustment was available by moving the
hip belt up or down a bit but, in reality, one simply needed to be the right
height for it to fit properly. Later Tioga's provided two horizonal stays
and the straps could be attached to either of them but this was only
marginally better. This is why most women hate external frame packs. They
don't fit. Although Dick Kelty was the inventor and pioneer of the hip belt,
the Jansport people soon designed a better pack. On the Jansport pack the
horizonal member is adjustable vertically as are the swing arms. It is
possible to set the pack length exactly and position the load relative to
the shoulders, up or down as desired.

Looking at the 77 Kelty Kids, it is clear that the pack lengths are too
short. Dick had not yet added that second horizonal stay yet. The load is
carried high enough but any pulling back on the pack [a given with a load
carried high]would compress the shoulders. In later years Jansport went to a
yoke system on its external frame packs. The added control was a big plus. A
real strength of the yoke system is the ability to keep the shoulder straps
loose while walking down the trail [the stabilizing straps prevent the pack
from tilting backward] while tightening the straps [and loosening the
stabilizing straps somewhat] over rough terrain. 

It would be trivial to add stabilizing straps to the 77 Kelty pack. Simply
sew the strap on the shoulder strap just before the shoulder and attach them
to the vertical center stays. I make this suggestion in an effort to help
out the 77 thruhikers on their mandatory 2003 thruhike.

And to John who wants a custom pack custom fit to his body, I will loan my
Jansport frame.

-----Original Message-----
From: John Musielewicz [mailto:jm@bluebuzz.com]
Sent: Wednesday, June 26, 2002 12:27 PM
To: pct-l@backcountry.net
Subject: Re: [pct-l] 1977 Thruhike disqualified. Go back and do it
again.


I donno. I've used external frame packs with the size of load you are
talking about with straps at less than a 45 and now an internal with
straps at a 45 find about equal carrying capacity at a medium heavy
load like 75+ (up to maybe 85 or 90). If I was carrying a  heavy load
now and carrying it any distance I'd want to use a good custom pack
frame, probably something along the3 lines of a packboard,  anyway
with the load properly distributed and lashed which you really can't
do with these commercial packs. Then I would be worrying about the
angle of the straps and want the angle custom fit to my body. I would
certainly want space between the upper part of the straps. Curious to
know what a yoke suspen is since a yoke is quite diferant in design
from a backpack suspenstion.



On Wed, 26 Jun 2002 14:31:53 EDT, you wrote:

>Reynold writes:
>
>> You were carrying the load too LOW. On a non-yoke shoulder system the
>> shoulder straps should go up from the shoulders at a 45 degree angle to
the
>> frame. Generally, this means the location where the straps join the frame
>> should be 2-3 inches above the top of the shoulder.
>
>Yea, right.  Just try to carry that large of a pack, filled to the gills, 
>weighing it at 75+ lbs with the shoulder straps going back at a 45 degree 
>angle!  You would have to have the damn waste belt pulled into what the old

>Aussie convicts used to call a "gut pinch".  The waste belt would be so
tight 
>that it would cut off circulation to your hips and legs and you'd fall down

>like a pigmy overloaded with an elephant just twenty yards down the trail.
>
>With that much weight you HAVE to balance the load of the weight between
the 
>shoulders and waste or else one or the other wears out.  It typically is 
>shifted back and forth to lessen the deadening of nerves in either place.  
>
>What the hell is a "non-yoke shoulder system"?  I'll take mine sunny side
up 
>with the yoke please, but throw away the white!
>
>Oh, any any salty '77er worth his damn wouldn't turn states evidence on a 
>comrad for all of the polarguard in China!
>
>Greg
>
>"Salvitur Ambulando"
>(walking solves all things)
>            St. Augustine
>
>
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