WOW! So Bill, is a big reason for the recessed bars to get a shorter RL, and thus less required distance between the trees and tarp length? Great posts!
WOW! So Bill, is a big reason for the recessed bars to get a shorter RL, and thus less required distance between the trees and tarp length? Great posts!
Depends who you ask...Originally Posted by BillyBob58
If you were to ask Grizz (at least if I were to heavily paraphrase a few things he said in his 'history videos' and a decades worth of contributions):
The reason to move the bar has more to do with getting the most possible spread out of a given bar size, and therefore increasing comfort.
If you were to ask me...
Reducing pack weight is an interconnected spiral... design more accurately a meditation spiral.
If you put the bar just where you need it... you can use a smaller bar.
If the bar is smaller... you can use a shorter dogbone length.
Getting results with those two... leads to a shorter RL... which leads to a shorter tarp.
Once you've reach the center, you can turn around to a spot along the path you're comfortable with.
In this case- 26" .490 easton aluminum poles with an 8' RL was the closest to the limit I could find... so I turned around and built back up from the center.
Which puts you back at the start as you can then take the bridge itself out of isolation and approach the tarp, or UQ, or next item in your kit with a fresh perspective.
Part of design is realizing how something works. Walking all the way down a path and turning around brings you new perspective on that design from different angles and uses.
An end bar is elegant in it's own right... but limited by the fact the user has to fit between the two bars. That limitation limits other options like RL length and tree to tree distances.
All designs have rules for them to function... and if you focus on a certain feature you can drill down to the reasoning behind those rules.
You have to 'break' the design in order to break the rules it imposes... to me that's what recessing the bars allows you to do with a bridge.
I’m not the expert that the professor or Bill is... but I believe recessing the bar allows you to achieve the maximum width of the hammock body to reduce shoulder squeeze...
That also why a lot of folks use shorter bars at the foot end... I have never heard anyone complain about “foot squeeze”,,
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“The only thing necessary for the triumph of evil is that good men should do nothing.”
- Edmund Burke
Way back in the day, about 09, the Jacks built me some custom bars- made and shipped for free- after a phone discussion about problems closing tarp ends due to spreader bars. Just something they made on the spot and sent to me to experiment with. The thought was that if wind was coming in the ends, you could put the foot end into the wind and use these bars in place of the wider stock bars. This did allow me to close the tarp up, or mostly so, and I don't recall any noticeable decrease in comfort. Maybe some, but not significant.
You can see the ends closed here, using the longest of the shorter bars, and how much room there is on the side pulled out with Grip Clips.
And in this next pic, even with the normal sized JRB bars, you can see how much room there is, with the 11X10 tarp closed on the ends, on the right sid which is pulled wide using a Grip Clip:
Last edited by BillyBob58; 05-31-2019 at 21:38.
Since we're having a more technical discussion- a finer point.
The reduction is shoulder squeeze is a side effect... sorta like shorter RL length.
You could reduce shoulder squeeze in an end bar bridge by increasing the bar length without resorting to recessed bar design.
You could compare the BMBH to the RR to see this concept in practice as that's nearly exactly the difference.
So to better clarify;
Early on spreader bar materials were very much a mystery. Short of custom fabrication or just using a dowel, pipe, or branch it did take a bit for a member here (schrokum or something?) to give tent poles a try. Even then that was considered pretty sketchy early on.
So while we are pushing further now with 3/4" Dia Easton poles... about 36" was a pretty decent limit early on as far as spreader bar length that was safe to work with.
The impetus to recess the bars then becomes "If I have only 36" of bar to work with, how do I get the most out of it?"
Yar: the point is to reduce shoulder squeeze and improve comfort.
To your point- you don't actually want the maximum width of fabric possible. Much like a gathered end requires a RL length that is neither too long nor too short... that's a good way to picture the ratio of bar length to fabric length.
So what you want is the 'right' length of fabric to match a given spreader bar size.
If that's not working you need to move the location of the bar relative to the user... or change the bar size.
If you simply increase the width of the fabric... you just make the bridge deeper and deeper... actually increasing shoulder squeeze.
With an End bar design- increasing bar length is really your only tool if you're working with the minimum bed length.
Simply moving the bar is what breaks the design and lets you play from there.
Grizz and I have our own 'magical numbers' though since I believe in voodoo mysticism as much as science I put a bit more emphasis on those ratios and use them to help balance bridge designs out. Too little fabric and you kiss the bars... too much and you squeeze the shoulders.
So ultimately- think of the bar/fabric like a gathered end seen from the side. (in cross section of the bridge).
Then you can move that cross section around to just where you need it.
My original micro ideas actually started with the premise that your butt is the heaviest part. So the primary bar is actually recessed to about your mid thigh or just under your butt cheek. To get the occupant in... the head is an end bar with minimal fabric. You slide in a bit like a sleeping bag with a half zipper. But since the 'bridge' part was running head to butt... the bedspace was very small... and the RL was as well.
The point being- in that case the bar was recessed to the other extreme (from the foot end) to both maximize a 26" bar as well as reduce RL distance to a minimum with zero concern about shoulder squeeze as it was designed for side sleeping. Since it was a side sleeper... it had a much different bar to fabric ratio as well.
Skinning kitty cats all around really.
And for what it's worth- heel/ankle squeeze is a real thing and a complaint I get about other models.
A bit how some GE users complain about that foot on the edge of the hammock getting torqued by the edge... with the heels or ankles forced together it can torque your knee or joints if you've had injury or wear there... or just limit your sleep positions on the lighter side.
All things in balance.
Definitely much more technical...
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“The only thing necessary for the triumph of evil is that good men should do nothing.”
- Edmund Burke
A random thought: has anybody tried adding tie-out points to the bottom "corners" of a bridge hammock to shock-cord them out to the ground? If so, what obvious problem am I missing with it? It seems, from first glance, that it would flatten out the bottom of the bridge, allowing for less shoulder squeeze without needing longer bars/wider fabric.
The force on the compression bars is roughly equal to the occupant- So you'd break nearly any shock cord you tried.
Grizz built a 'barless' bridge at one point.
A wonderful two part that covers early bridge development- part one covers the bars and the introduction to recessed bars.
Part 2 shows FJR's narrow foot concept as well as a bit of a nice hodgepodge of what was going on.
You might note Brandon popping up in the hodgepodge as the BMBH predates this bridge series but the Ridgerunner does not.
These videos are 10 years old but to be honest... since then you could primarily follow Grizz and VW who jump out at me as the bigger innovators along the way since then as the early fire cooled and nothing else really sticks out to me as truly unique. Grizz produced his 'counting grams' video which for me was the most pivotal... closely followed by his Ariel videos since then.
V.Allen did produce a 'Big Guy' bridge for a short bit for a few here. I think one or two are still bouncing around but there were some durability issues.
And you've heard enough about me, lol.
Last edited by Just Bill; 06-01-2019 at 12:53.
Hi Just Bill,
Thank you for such an encompassing discussion of bridge hammocks.
JIM
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