Re-shockcording Tent Poles – What type & length of shock cord to use?

[Ethan A.]

I've got a Sierra Designs Meteor Light CD which I use for car camping. Though the tent is in great shape and I always store the poles open to preserve the shock cord, with enough time the original shock cord has totally stretched out. I don't have the poles in front of me at this moment, but I think each of the three poles is around 162 in. long.

What type/width of shock cord would you use and how much shorter (% of total pole length) than the length of the poles would you make it, so it's effective but not too tight?

For width and type, I'm thinking 3mm marine or military grade shock cord, like this: http://www.uscargocontrol.com/Flatbed-Trailer-Products/Polyester-Shock-Cord

Found one recommendation on Instructables to use cord that's 50-75% the length of the pole and at least 3mm thick. 50% sounds too short to me and would probably lead to a shorter life for the cord.

[Stephen M]

Might be worth calling Sierra Designs
as they may send you replacement cord.

[Ethan A.]

Thanks Stephen, I have a call to them on my calendar for first thing Monday morning. i'm sure they'll have good guidance on the length of cord to use, though I'm not confident they use the highest quality shock cord themselves based on what I found in the poles, just what's good enough to get the job done.

The Meteor Light CD is an incredibly roomy double wall tent for two in terms of width, length, height and usable space. I wouldn't want to carry the weight backpacking, but it's very nice for car camping.

[Dan @ Durston Gear]

I've bought shockcord from QuestOutfitters for use inside tent poles.
http://www.questoutfitters.com/narrow_roll_goods.htm#ELASTIC%20CORD%20&%20SHOCK%20CORD

I think 1/8" is a pretty standard choice by manufacturers, but you can save a bit of weight using 3/32". Opting for 1/16" seems too light in my experience and it's not really useful.

It terms of length, just tie it inside the pole without gluing one of the end tips in place, and then you can re-tie to experiment with the tension until you're happy. You'll probably be happy with about 65% of the length.

[David Thomas]

E J: If Sierra Designs isn't forthcoming on some shock cord, PM me. I've got a roll of 1/8" and a roll of 3/32" – more than I will use in many years and could send you whatever lengths you need.

If you don't use it for backpacking, go with the 1/8". Who cares about weight while car camping.

Dan's estimate of 2/3 of the pole length sounds good, maybe a little long. I stretch it pretty tight so it does it's job more forcefully and quickly. A pair of Visegrips is very helpful while installing the shock cord in the poles. Stretch each length in each section to the max, Visegrip it, then you'll have plenty of length to feed through the last section.

[Roger Caffin]

For my tents I use a length of 3 mm bungee about 1/3 of the whole pole, but I add Spectra string to the ends to bring it up to about 3/4 pole length. I put the bungee cord in the middle, and make the first fold of the poles also in the middle. That way there is minimal movement of the cord inside the poles. Yeah, techie, techie, techie…

Oh yes – clamps (forceps, actually) on the string to get it all the way through – TOO RIGHT!

Cheers

[Ethan A.]

So according to what I found online and Sierra Designs, the industry standard is somewhere around 75% of pole length, but a little tighter than that I'm sure does no harm so Dan going with 65% sounds fine.

Roger that's a great idea about Spectra cord in the middle – which width of Spectra do you use and what knot do you use to tie to the shock cord?

David thank you for the kind offer. My best guess is that Sierra Designs used 3/32 in (2.38mm cord) for the original cord, which I think is fine.

Stored right the shock cord should last at least a few years.

One caution to share from a friend's experience – he stored his tent and other gear in an attic that would heat up more than the rest of the house – definitely reduced the life of elastic cord, PU materials and glues in footwear. Some of his gear that was supposed to be supple crunched when we handled it.

[Roger Caffin]

> which width of Spectra do you use and what knot do you use to tie to the shock cord?
Oh, pretty light stuff – 1 mm or less. Spectra and Dyneema are awfully strong. Rubbing and wearing would be the main concerns, but if you have to replace it once every few years … So?

Knots: more tricky, especially with Spectra. Dyneema is better. First I melt the nylon at the end of the shock cord to make a bit of a lump there, for safety. The knot itself is usually a clove hitch with some extra loops, pulled very tight. You will need to tie off the FREE end of the string as well, to stop the it from 'running'.

I drill a hole in the end of the pole foot and run the string through that before tying a figure of eight knot. The knot fits in a countersunk recess at the end of the pole foot so it doesn't abrade too much.

Oh – I had better repeat: I put the shock cord in the MIDDLE, with some string at EACH end. It's much easier to poke string through the pole foot than bungee cord too.

Cheers

[Eric Blumensaadt]

OK Roger, that idea of making the first fold in the middle of the sections to decrease folded tension sounds right for some reason.

But I am not going to try to fathom the exact physics of this suggestion (B/C it will make my head hurt). I'm just gonna place my faith in your tenting experience and do it to all my tent poles.

But I do see the reasoning for the Spectra tent cord at each end of the shock cord. Very sound idea. When I repair/replace a pole shock cord I'll make that mod. Since that cord does not stretch I'll make the total cord length 75% of the pole length and hope for good tension.

Gotta say Roger, you and I differ in a few ski touring bits but you have helped me choose stoves and inspired me to modify tents to resist snow and wind loads. I don't care what your wife says, I think you are a scholar, a gentlemen and a judge of good stoves and tents.

[Roger Caffin]

Hi Eric

> I'll make the total cord length 75% of the pole length and hope for good tension.
Eh – best allow for some tuning, because I do not know what shock cord you have. Probably different from mine. Tweak to taste.

> differ in a few ski touring bits
That probably reflects the differing terrain for each of us. I can't do what the guys with T3s and Tele skis do! But they can't keep up with us on the flat or the climbs!

Cheers

[Daryl and Daryl]

If the tension on the shock cord is too wimpy you run the chance that the tent pole ferrules will not be fully seated when you set the tent up (e.g. in the dark). This is a real easy way to break a pole.

For this reason I err on the side of stronger shock cord (e.g 1)/8"" and a lower % of pole length (e.g. 65% instead of 75%). U want the poles to be tightly seated when I set up the tent.

Caution, however, if you go with my logic you need to take care when assembling the poles. Don't let them snap together. You may damage the poles….especially carbon fiber. Hold and guide them when assembling the poles so things come together slowly and without damage.

[Roger Caffin]

All of what Daryl wrote – definitely!

Cheers

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