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PU covered depower line check?

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happytrees
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PU covered depower line check?

Postby happytrees » Mon Nov 16, 2020 9:45 am

Hello :D
Do you check this line? Never. Only if pu cover stuffed. Occasionally?
Any breakage incidents?
Thanks for help

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Re: PU covered depower line check?

Postby evan » Mon Nov 16, 2020 10:04 am

There are two methods to cover a line with pu:

- tight fit, sand can't get inside the tube and the line inside will last longer than the outer tube.

- loose fit, sand gets into the tube and wears down the line. These will fail with no visible clue on the outside.

Sadly the majority of the industry chooses the second option as it is way easier (cheaper) to just loosely slip a pu hose over a piece of rope instead of making a sand tight fit.
Shockingly they often even put a line inside that is just barely rated for the maximum load when new and it depends on the user if they will get more than a few sessions out of it. Sharpness, grain size of the sand and how often you flush the sand out of the tube will determine the amount of sessions you can get out of it.

A good example is the duotone click bar: the red loaded flagout line that runs loosely through the tube can be destroyed in weeks when not cared for, while the grey line that runs tightly through the other chamber of the rectangular tube will outlast most other components of the bar.
Both lines are loaded equally and both run through the bar experiencing the same amount of abuse, yet there is a huge difference in wear between the two only because one has some wiggle room and the other none.
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Re: PU covered depower line check?

Postby Herman » Mon Nov 16, 2020 11:33 am

Maybe the only semi accurate answer you will get - not often enough. In truth I don't use pu covered centre lines because I did not like the sticky feel in the bar dugout but that has probably improved from the early stuff I tried. However I use chicken loops and the same problem arises. I would like to be inspecting them much more than I do. In my dreams I would have a loop that was plugged in at both ends so that it could be replaced with a spare while inspecting/replacing the inner. Arguably if you cannot inspect you should replace after a given amount of use in defined conditions, including abrasiveness of sand................ A good question but I will be surprised if you get a definitive answer.

PS From a development point of view you could start by inspecting every 5 sessions. This rate could then be extended after gaining experience but I doubt that anybody will have done that. I can think of one manufacturer that stipulates an annual change of dyneema in their chicken loop but I believe this might be driven by national HASWA regulations.
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deniska
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Re: PU covered depower line check?

Postby deniska » Wed Nov 18, 2020 2:36 pm

evan wrote:
Mon Nov 16, 2020 10:04 am
There are two methods to cover a line with pu:

- tight fit, sand can't get inside the tube and the line inside will last longer than the outer tube.

- loose fit, sand gets into the tube and wears down the line. These will fail with no visible clue on the outside.
Do you have any examples of tight fit designs that never failed (until visible wear on the plastic)?
I presume core sensor2s is tight fit.. I snapped PU line in the first 6months with no noticeable wear on the white plastic shell.
my guess is that salty water still gets in and perhaps helps to create salty crystal deposits?
I also snapped "loose" fit designs (RRD v7-8 bars)..
the issue as you mentioned - sand is pretty hard to clean with regular rinsing...

So my personal stance is to get uncoated lines whenever possible.. way more predictable and easier to service...
Sadly fewer brands produce "uncoated" bars these days..

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Re: PU covered depower line check?

Postby evan » Wed Nov 18, 2020 3:25 pm

deniska wrote:
Wed Nov 18, 2020 2:36 pm
Do you have any examples of tight fit designs that never failed (until visible wear on the plastic)?
I presume core sensor2s is tight fit.. I snapped PU line in the first 6months with no noticeable wear on the white plastic shell.
my guess is that salty water still gets in and perhaps helps to create salty crystal deposits?
I also snapped "loose" fit designs (RRD v7-8 bars)..
the issue as you mentioned - sand is pretty hard to clean with regular rinsing...

So my personal stance is to get uncoated lines whenever possible.. way more predictable and easier to service...
Sadly fewer brands produce "uncoated" bars these days..
Older Ozone with a 5mm cord in a 8x5mm tube.

Core is indeed an exception as they are running a very thin line through the tube that is rated too close to the breaking strength when new already.

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Re: PU covered depower line check?

Postby Herman » Wed Nov 18, 2020 6:38 pm

Bear in mind with covered centre lines. To inspect properly you will probably have to disassemble the chicken loop rotor head. These rotor heads look neat but will often only take a small line. Another reason I avoid this type of system. That’s not to say that it cannot be done well, it is just that this sort of design philosophy is not for me. I generally rig my own bars.

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Re: PU covered depower line check?

Postby Faxie » Wed Nov 18, 2020 7:30 pm

I have a custom bar with a tight PU cover, and replaced it after 150 sessions or so because the line is one part that includes the trim, and the clamcleat frayed the line a bit. Had a chance to inspect the part of the line that went underneath the PU, and it had no damage whatsoever.

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Re: PU covered depower line check?

Postby JakeFarley » Wed Nov 18, 2020 10:26 pm

A couple of years ago I replaced the PU centerline tube on my 2010 Cabrinha Xbow as it had cracked. The old tube had two chambers, one for the centerline and one for the flagout line and was pretty loose fitting (I could spray water on one end and rinse it out the other end). When I disassembled the tubing, there was no wear on the centerline or flag out line (probably because I rinsed my bar after every use). The new tube was tight fitting so no sand could get in. It was difficult getting it all set up correctly. About a month ago I had to use the flag out when overpowered and it worked good (except that the old Xbows flagged out to the two front lines - high Y setup). I think I got the PU tubing at Home Depot.


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