So if we wanted to order exactly what you have shown what would we ask for?
So if we wanted to order exactly what you have shown what would we ask for?
I thought my CF mountain bike handlebars were sexy too until they snapped on me while riding. That's one trade off you risk with any ultralight component that's subjected to any kind of load.Originally Posted by LuvmyBonnet
But yeah, whether it's a pole or a canoe... Carbon fiber is definitely sexy.
Basically, don't scratch it. Scratch marks or slight gouges will eventually develop into cracks.
I agree that definitely know where your carbon is made and how because it makes a big difference. Also this guy in this video highly advised making sure that the repair shop installing carbon on bikes to be sure they user proper torque or the carbon would fail.
https://youtu.be/-qsLYlVWkbQ
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"What lies behind us and what lies before us are tiny matters compared to what lies within us" - Ralph Waldo Emerson
I asked for fat guy carbon fiber spreader bars and he sent me a PayPal invoice for RR Hammock Spreader bars(710 head, 600 foot) rush order for $90.00 USD + Shipping $6.00 USD = $96.00 USD Total.
Got them in 4-5 days and the were in 4 sections. 2 section header bar size 710 and 2 section footer bar size 600.
I believe they are based on the sizes listed on his tent poles page.
http://www.rutalocura.com/Tent_Poles.html
710 Info: http://www.rutalocura.com/tent_pole_710.html
600 Info: http://www.rutalocura.com/tent_pole_600.html
"What lies behind us and what lies before us are tiny matters compared to what lies within us" - Ralph Waldo Emerson
I really like these and like everyone else I wonder about the durability since when you get out there...I mean really out there where you don't want any issues where you get hurt. Even though I just got these, I've been thinking about rigging a failure test in the name of Hammock science for us all both on the stock WB bars and the RLCF bars. Let me know what you think and if I should do this. I have all the supplies except for the scale. See my chicken scratch sketch below:
SpreaderBarTester.JPG
"What lies behind us and what lies before us are tiny matters compared to what lies within us" - Ralph Waldo Emerson
I'm assuming as long as these bars are as straight as an arrow they can easily handle hundreds of pounds of compressive pressure squarely applied on each end....??
Don't know...i don't think anyone knows exactly how much load from what understand.
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"What lies behind us and what lies before us are tiny matters compared to what lies within us" - Ralph Waldo Emerson
Generally-
The 600 and 710 is simply an easier way to type the bar diameter and is .600" or .710" and I believe simply comes from the sizing of the raw tube.
All tube is not created equal or laid up the same... but the mysteries, flavors, and properties of CF pole mockups are not my area of expertise.
That was why I reached out to Josh for my needs.
I basically think of them as roughly equal to our common pole sizes in AL. .625" (5/8") and .75" (3/4")
Bar length- over 36" you should bump up to .75" or .700" Carbon. Regardless of weight.
So doing a mixed diameter set for the RR is a good plan as well. That said- there are some folks lighter than 200lbs who are using .600" bar at head and foot.
There is also the potential to use smaller bar diameter at the foot end if you are lighter.
Two piece poles are stronger than three piece... if nothing else because you introduce less chances for movement or deflection that could cause off-axis loading.
Or to put it another way... to go from 'straight as an arrow' to a compound bow.
From what I understand- all these poles are very strong in compression. Though I don't believe tensile strength directly corresponds to compression strength.
The issue with any bridge is that you are not guaranteed to load these completely inline.
With a recessed bar bridge like mine you also introduce the higher possibility of bumping the bar in some way.
So the problem isn't if the pole is loaded perfectly in compression in a static situation, but what happens if you sit on the edge of the bridge a bit too hard, bounce your weight, twist as you roll over... or dozens of other dynamic loads you could introduce.
There have been some broken RR pole sets. A couple of forum members have reported breaking poles. Usually from a harder than intended entry.
SO... long story short...
My current take is to treat the carbon poles as equal in strength to AL. It might be possible to push them further with more testing- but cutting the weight in half (roughly) without a compromise in strength seems to be a fair enough trade to this point in my opinion.
I think it's way to early to say that CF poles exceed the strength of AL poles.
Is the potential there... perhaps... but do I want my head near them while we sort that out... no.
For what it's worth for those who don't know- I build the lightest bridge which uses Easton .490" poles to support up to 200lbs. So I am not a conservative person when pushing SUL stuff. But the risk compared to the reward is too high and we are already getting a big bonus with CF poles in terms of weight savings. When an AL pole breaks it typically bends and then collapses. CF has a potential to shatter, shred, or splinter. So pushing AL may lead to a bump on the bottom or surprising shock as you end up in your bridge taco. But CF failure has a very high potential for serious injuries.
I've been thinking of rigging up something similar once I move.
I believe that the weighted portion though should be a single piece. In your sketch you are loading them in 'ideal' conditions.
If you turned those two cables into a single loop- then attached a small basket (like a milk crate) I think that would better simulate the single point loads that a bridge has to deal with.
Basically- one of the hardest things on a bridge is simply getting into it. Your full body weight is sitting down onto a roughly 2'x2' area and concentrating that load onto the fabric before transferring it back to the suspension.
When you sit down on one edge, nearly your whole weight is on that side... so in theory you are cross loading the pole, and as you rock your bodyweight into the bridge that load rolls across to the far side before reaching a balance.
So the sketch you have... might be enough for a static test if the failure load produced was very high.
Much like rope or suspension you loaded up 1000lbs before failure that would produce a 5:1 for a 200lb occupant and be quite encouraging.
To that point as well- I think it would be important to use the actual suspension components too (rather than cable).
For the RR... that would mean the webbing and buckle (or at least the hardware so we don't are not testing the stitching)
For mine... that would mean the spliced amsteel.
I would be very interested in consulting Grizz and a few others here about how best to establish a test and would be willing to put some money where my mouth is in regards to testing.
Might be time to start a new thread?
I do really like the engine hoist idea!
I've been debating where and how I could test safely considering that a failed CF pole could shoot splinters and any pole could really cause some issues.
Anybody who has ever used a recessed bar bridge and had a pole shoot through the body knows that they shoot with considerable force.
I don't have access to anything like that and it's either hang the rig off the steel in the basement or a tree in the backyard. The issue with both is adding weight safely. I figured I could rig some type of system to hoist the load with climbing gear... but hiding behind a sheet of plywood while you pump the engine hoist lever seems safer for sure.
To give you an idea... here's a video I made to demonstrate bridge loading.
I was thinking that adding the load in same condition I am using the piece of webbing I sit on would best test the poles.
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