Inflatable spreader bars?

[cmoulder]

If 28oz is your target weight, hammocks already compete favorably with ground setups. A Dutch Half Wit (GE) with Venom straps for suspension and a LL Operator UQ weigh right at 20 oz, and a DCF 11' hex tarp weighs about 7 oz with guy lines, so you're there already. Ditto for bridges if you use trekking poles that double as spreader bars.

If you want to try to make even lighter carbon fiber spreaders, here is a good source that I have used. Excellent quality and relatively inexpensive... a hard combo to find for small quantities.

I've made my own trekking poles for a few years, some of them with well over 2k miles (probably over 3k) on them with no damage. I'm not hard on gear but I don't baby them, either. They weigh 4.1 oz each (same as GG LTs), and one pair I modified slightly to make them double as spreader bars. IMO/IME they are rock solid, and carbon fiber is (or can be) a lot more durable than many assume... at least the roll-wrapped 3K stuff linked above.

For those trekking poles I use 11mm and 13mm OD with 1mm wall thickness, but I would venture a GUESS that for dedicated spreader poles you could use tubes with 0.5mm wall thickness with an OD of 15-16mm, thereby getting the weight down to about 4 oz/pair for 36" long, 3-section poles with ferrules. I would highly recommend 3-section mainly because you don't want a ferrule in the center, and 3-section would of course fold down more compactly. I ordered the 16mm/0.5mm and 15mm/1mm material and am going to make a pair of these.

No manufacturer or cottage folks are going to recommend any of this, and certainly would not sell such a thing to the general public.

[Just Bill]

Thanks for the words, JustBill.

I got curious about this in pursuit of the question, can a hammock compare to ground gear in weight? I'd always assumed it was no, until I took a closer look.

Considering that I use a 12oz insulated mattress (NeoAir X-Lite), and any durable ground cloth will weight around 2oz, one metric to judge a hommock by is 14oz for hammock + suspension + UQ. The other is based on a 1lb ground shelter (full bug/rain protection), plus that mattress, so 28oz, all in.

Setting aside the spreaders, I figured bridge hammocks could get lighter since they use less fabric. Thus the focus on spreader weight. But again, I'm new to the hammock world. And I am curious about the comfort factor - this isn't entirely in pursuit of shaving a few ounces.

JustBill - can you offer any details of your 9oz bridge?

I'm also wondering how this would fare scaled down to a spreader, and if carbon tent poles would be strong enough: https://backpackinglight.com/forums/topic/106769/ That could be in the realm of 3oz/pr.

If you want to talk UL bridges... you gotta start where I started with the man himself-



I started making bridges because I simply hated gathered ends. Too much fiddling, playing, and setup issues night to night. For speed hiking you need to slam up camp and get a good night's sleep.
Granted a bit of that was simple ignorance and lack of experience but as a hammock newbie I found the consistent pitch and easier to control bridge more appealing.
I also needed to retain the ability to sleep on the ground... I owned quite a few pads but no UQ's... and pads sucked in the gathered end.

As you mention... without springing for Cuben... a good UL ground sheet is always a challenge. A bivy that doesn't let you down when you need to throw down in any conditions.
You can get some UL fly material at a good price that performs well. Getting off the ground lets you remove the heaviest component (waterproof floor) and improves your comfort. In wooded areas it also extends your camp selection, speeds up packing/setup, and greatly reduces managing wet sloppy gear. If you retain the pad... you can still throw down in a shelter or cowboy camp in an open meadow, distant peak, or in the bushes at the post office waiting for them to open. So for a fast and light long distance system it really is a compelling piece of gear.

By sleeping inline you can also cut down on tarp size a bit... or at least more predictably design a tarp you won't be poking out of every time you change position.
This also gives you the opportunity to go to a stakeless system which further reduces setup... bringing you back to the general 'Air Bivy' idea.

As far as I know... I'm still the only one brilliant (dumb) enough to hang on .490 easton Aluminum poles. That took quite a bit to work out but that is the lightest pole material I am aware of.
Granted this was before the days of carbon fiber poles as well... which greatly improve our options.

That 9 ish ounce bridge was based upon one simple concept, 'Beat Grizz'.
Float a sleeping pad in the air, use it to help give the UL bridge a little structure and rigidity... and get the lightest pole I could find- 26" Easton .490.

The other reason to chase these is the 2lb challenge. Rain, insulation, bugs, shelter for summer 45* and up conditions... ideally in a package you'd actually want to use. Best I did at the time was 36 ounces.
I also was designing these for a very specific FKT on the Florida Trail where there are sections where you cannot sleep on the ground... having the bridge in the arsenal meant that the person making that attempt was not limited to specific campsites and could literally sleep in the swamp if needed.

Here's a collection of random early bridges. https://1drv.ms/f/s!Apygyt54yYPwhIMYHi-tYOLz1NdsuA

The Black and Olive ones are what became known as the Micro Bridge. They were based upon a Large Neo-Air/Xtherm.
I don't actually sell it anymore as it's really a bit silly... and I'm creeping up with some of my full size bridges on that original weight anyway.

There is my summer and winter stakeless tarp systems in there too. The Summer tarp can intentionally be pitched very high (like a sunshade) for mild conditions.

There's one with my wife and daughter that took the 'floating pad' concept literally. But that ended up being a bit of a bust IMO, but it was cool.
Besides the double layer (who needs all that fabric )... the pad was trapped in there so if you did want to just toss down the pad for a quick sleep... you had to throw the hammock down too. I found I preferred to have the pad just dropped in the bridge, especially on the AT or in some areas around here where you might be running 50/50 on the ground air mix.

In real life... people like breakdown spreader bars. Even my craziest super anal SUL FKT athelete wanted to add the ounce back to the micro bridge to breakdown the 26" poles.
So in part that was one reason I got away from the micro sized bridges as I had to custom build those to get them to work.

lately I've been going with Carbon. Cmoulder is ahead of me for sure, and I simply turned to Josh at Ruta Locura for my needs. I was never a trekking pole guy, but as I have crossed past 40 I probably will need to revisit it. So I cannot say how far his suggestion is pushing it... but a thinner wall, single piece CF spreader may indeed provide a means to lighten things even further. I would think a 5/8" or so thin wall 30" bar would be a likely single piece candidate to play with. That's typically the maximum manageable size people can handle...

With spreader bars... the larger the diameter... the stronger they are.
The least amount of joints, the lighter.
While I agree with Cmoulder... a three piece is often stronger. Might be worth a careful look to see if a three piece 5/8" set might not weigh more than a two piece thin wall set in 3/4"... I don't know the answer actually.
I haven't really taken the time to nerd out on CF bars and the possibilities. I just turned to Josh to see what worked and went with it. As Cmoulder mentioned though... what you can do for personal use is often different than what I can do for commercial use... so I suspect there is room there to improve.


Cmoulder also has a fine trekking pole set that seems to be working in a bridge thus far and you don't need to go full Tiggerworkz on a trekking pole to get it to work.
I worked with Ruta Locura to develop a set. https://1drv.ms/f/s!Apygyt54yYPwg7g3TpmRntjgzkvFlA


With no straps... the poles are just under 8 ounces. The bits and pieces to convert the trekking pole to bridge use adds about 2 ounces. That gets you a solid 36" spreader bar pair for 9.25 ounces total rated to 200lbs (I'm 230+ these days) You want to do some spreadsheet magic from there... that's up to you. Me; I've always been in Colin Fletcher's camp and consider 'from skin out' a much more useful tool than baseweight and shoving 2lbs of stuff in your pockets and carrying half your shelter in your hands all day to pretend you're SUL on your gear grams app. If you need to take it... it counts. If your shelter system doesn't work without your trekking poles... then count em. Really all you do is limit your options and thinking if you don't look at ALL your gear as a full system.

[cmoulder]

I received the 1Mx16mm/0.5mm tubes in the mail today. Two of them weigh 71.3g (2.51oz). The 0.5Mx15mm/1mm tube for ferrules is coming from China but shouldn't take much longer.

A sub-4oz (maybe 3.5oz?!) pair of 36" 3-section spreaders is entirely possible, maybe even with shock-corded sections. First-pass opinion is that these tubes are more than rigid enough for the task.

[Just Bill]

I received the 1Mx16mm/0.5mm tubes in the mail today. Two of them weigh 71.3g (2.51oz). The 0.5Mx15mm/1mm tube for ferrules is coming from China but shouldn't take much longer.

A sub-4oz (maybe 3.5oz?!) pair of 36" 3-section spreaders is entirely possible, maybe even with shock-corded sections. First-pass opinion is that these tubes are more than rigid enough for the task.

So.... how would you plug them for bridge use? 15mm I.D. or so?

16mm is close to .625"... I wonder if a standard locking tip for the AL pole would fit.
I can check some I have... just figured you might be ahead of me on how you plan to put on tips.

Honestly... I'd be more excited about a straight pole with no ferrules/joints.
The tips are fairly heavy... though I could potentially get some milled with a hollow center.

If I recall... the Micro had 3.75-4 ounce poles at 26" fixed length.
Since working on these new prototypes like the one you have I've been daydreaming a bit on a combination of my medium and micro in a hybrid recessed bar design like the micro was.
Maybe a 30-36" bar... In a fixed length pole with no ferrules.

Even discounting a revisited Micro or smaller size.... the Hybrid 1.2 version of what you have (Hexon 1.6) is 1.625 ounces lighter in the body.
My notes are a bit messed up but either way....

5 ounces for body, dogbones, and ARL
3 ounces for poles

That's an 8 ounce full sized bridge with little reason to even talk much about reducing the size much further.

Though in a hybrid design I can reduce the RL distance by roughly 2' or more... which would slip you under a 10' tarp vs a 12'... so that would be the compelling reason in my opinion to look at it more.
The Micro squeezed under a 9' tarp... but that's unrealistic with 36" bars to keep stress down on the poles.

[cmoulder]

I don't know just yet precisely how I'm going to handle the ends, but I have a general idea to layer up a laminate of smaller CF tubes and use a small, solid CF rod in the center to finish, OR I have some small aluminum tips I got from Quest. I'm pretty sure I can keep it well under 1 oz (for all 4), but I'm going to weigh (literally!) both options before gluing anything.

The hammock (your prototype) I have weighs 213g (total, with CLs), Venom straps are about 52g/pr, and with spreaders of ~106g (3.75oz) the total would be 371g (13.1oz) for a pretty darn robust setup, and decently roomy with 2x 36" spreaders.

I've messed around enough with it that I find it pretty comfortable with 36" spreaders, and could see how 30" at the foot could work. But 26" (head and foot?) seems like it would be very tight for me.

I don't know how to calculate the increase in compression force as the RL/dogs are shortened, but the seat-o'-pants engineer in me screams that it's a bunch. As presently configured, this force is handled easily by my trekking poles and I'm optimistic that it's not going to stress the light spreaders too much. But it's easy enough to go up in diameter and experiment with tighter rigging, I suppose.

Most of the FKT guys seem to weigh about 140 lbs so you can go really light with their stuff.

[MiteyF]

I'm just going to drop off a quick anecdote here, feel free to ignore it.

My buddy in college was a competitive cross country skier. During one race, a fellow in front of him with carbon ski poles planted incorrectly. The pole snapped and went clean through his palm. Composite poles (especially carbon and kevlar) placed under extreme stress can be much more dangerous than you may think. I'd hate to have a jagged projectile a few inches from my head, only to save an ounce or two in my backpack. I'm all for improving gear (and DIY/experimentation in general), just be careful!

[cmoulder]

Absolutely going to be careful with this, as I am when trying anything that's new or pushes the envelope a bit.

[Just Bill]

I don't know just yet precisely how I'm going to handle the ends, but I have a general idea to layer up a laminate of smaller CF tubes and use a small, solid CF rod in the center to finish, OR I have some small aluminum tips I got from Quest. I'm pretty sure I can keep it well under 1 oz (for all 4), but I'm going to weigh (literally!) both options before gluing anything.

The hammock (your prototype) I have weighs 213g (total, with CLs), Venom straps are about 52g/pr, and with spreaders of ~106g (3.75oz) the total would be 371g (13.1oz) for a pretty darn robust setup, and decently roomy with 2x 36" spreaders.

I've messed around enough with it that I find it pretty comfortable with 36" spreaders, and could see how 30" at the foot could work. But 26" (head and foot?) seems like it would be very tight for me.

I don't know how to calculate the increase in compression force as the RL/dogs are shortened, but the seat-o'-pants engineer in me screams that it's a bunch. As presently configured, this force is handled easily by my trekking poles and I'm optimistic that it's not going to stress the light spreaders too much. But it's easy enough to go up in diameter and experiment with tighter rigging, I suppose.

Most of the FKT guys seem to weigh about 140 lbs so you can go really light with their stuff.

https://1drv.ms/u/s!Apygyt54yYPwgvJ60JtdMcYlM6KxzA

That's the Micro- you'd need to go to something like that to drop to 26" bars.

I didn't mean to imply that you could/would/or should slap smaller bars into the one you have.

Simplest way to say it- I start with the bar, then design the whole bridge around that.
So with mine you can't really play with the bar size or dogbones at all.
Can I cheat a little for an FKT... sure. But I'd only do that for the actual attempt and with good reason.... like say there is a fella who really loves his cuben poncho tarp and you need to get a few inches back on the RL distance so he can pair it with that piece. And he's only 160lbs and very well informed about the gear he's using. (I only work with the 'heavy' FKT athletes, lol).

I was inspired by trying to go head to head with Grizz's counting grams video... the only way to do that was to start with the lightest bar I could find and work backwards from there. As a result of that... I actually tend to be more conservative than Grizz or any other vendor in balancing my bridges. I couldn't rely on a heavier bar to take up the slack. Using grosgrain on the edge rather than webbing... everything has to transfer very cleanly and be just right to avoid blowing out 1 ounce fabrics. I can't crunch the numbers to demonstrate any of it... But I do have my own math I use for things to balance all the forces as evenly as possible. The key variable is the bar length.

So basically... you come up with a SUL bar... and my mind spins to other designs and older failures that might see new light.

While the 26" micro was about the floor in my opinion of usable bridges (Dutch had a thong sized bridge skin prototype at one point for example)... A micro type design with a 30" no-ferrule bar might represent a more practical option than the 26" micro... but in real life 26" was the furthest I could push the .490 pole at the time. So a thin wall Carbon pole that's even lighter... opens up that possibility.

That said... as you point out... the current prototype you have is an excellent example of what happens when you take a step back from stupid light, and one more step back from FKT light... to get a fairly sturdy, good sized, and usable piece of gear. It is a good bedspace for average size people... generous even for slimmer trimmer backpackers. With all those things coming together in a 10-14 ounce package; It's hard to argue to keep pushing things into a smaller package. If you come up with a practical pole that trims another ounce off that design... even better.

The prototype you have is the result of several factors, one being new materials.
So my mind is racing on several fronts as I consider the possibilities and revisit old ideas.
The oldest is the same basic premise of this thread: Could a bridge hammock form the core of a very solid SUL kit?

I still believe the answer is yes even if we remain a few ounces away... that's all we are down to at this point really.
I have most, if not all the parts and pieces floating around... but likely I need to see how this spring and summer goes with testing.
Might even be better to think of the prototype you have as a design premise more so than a finished product... if the construction technique holds up and the idea is working... I have other places I can apply it to greater effect. A good sized, solid, light, affordable bridge is a worthy product. But ultimately I think a hybrid style bridge will form the basis of that Harmony system I keep chasing.

[cmoulder]

JB thanks for all the additional info... and I think the prototype I'm playing with is going to be a big winner for you, with a Goldilocks combo of low weight and durability.

I am doing the UL spreader project purely for fun and will send them to you after I play with them a bit. (Assuming I don't crunch them.)

[autox]

Hey guys,

I've been enjoying this thread and learning what the state of the art on UL bridge hammocks is. Very informative.

Cmoulder, if you arrive at a 4oz set of spreaders, that will indeed address the ends I was hoping to reach with inflatables. Life has gotten in the way of further work on that from my end. I think I'll just wait and see how you fare.

On that note, have you considered making a 2 segment pole with an off center split? Saves the weight of a ferrule. 12"/24"?

Is there a reason metal end fittings are favored over fabric pockets? Or how about this: cut a 1.5" segment of ferrule, glue on a 1/4" segment of pole stock 1/4" from one end, drill a <1/4" hole in the short end of the ferrule (yup, just barely fits), run your suspension line through that, and finally insert the 1" end in to the end of your spreader bar. This will require some adaptation to get it to work, but you get the idea. All carbon fitting the inserts in to the end of your pole. The insert length can be rather short as there no bending moment around the pole tips. Maybe wrap some adhesive Velcro around your pole ends to secure the inserts via a mating strip attached to the suspension.