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Characterizing Dynamic Ropes

Original Post
Deimos · · Unknown Hometown · Joined Apr 2010 · Points: 35

For quite a while I have been wondering why climbers consider the principal characteristic of a rope to be its diameter. (Or, at least within a given dynamic rope classification -- single, half or twin -- diameter seems to be the characteristic that climbers focus on.)

When evaluating a rope, you can look up how many UIAA-standard falls it achieved, what the standard-fall impact force is, and what the static elongation is.

To get a sense of how durable a rope will be, you can look up what the sheath proportion is and maybe how many sheath bobbins are used and what the braid pattern is.

And, of course, you can look up how much a rope weighs.

If you review a bunch of these specifications, you will likely come to the conclusion that most of the properties of a good-quality modern dynamic rope (e.g. Beal, BlueWater, Edelrid, Mammut, PMI) can be estimated by knowing just the weight (g/m) and sheath proportion (%) of the rope.

In general, a rope with a lower proportion of sheath will have better dynamic properties (more falls for its weight, lower impact force and a better relationship between static elongation and impact force) at the expense of reduced abrasion resistance.

Also knowing the diameter provides a little more information -- a rope that is heavy for its diameter will undoubtedly have a stiffer feel. But knowing just the diameter of a rope tells you very little about it.

So why do we focus so much on rope diameter?

Wouldn't it be more useful to say "63g/m rope with 35% sheath" or perhaps "7-fall rope with 35% sheath"?

An example of the problem of focusing on rope diameter is the confusion that ensues when comparing ropes like the original super-lightweight singles that weigh around 55g/m. The first of these, the BlueWater Dominator, measures 9.4mm. A later rope with virtually identical properties, the PMI Erratic, measures 8.9mm. Those are both 7-fall ropes. Other 8.9mm ropes -- the same diameter as the Erratic -- the Mammut Serenity and the Edelrid Swift, are 5-fall ropes; they weigh 52g/m. The 8.9 Erratic is much more similar to the 9.4 Dominator than to the 8.9 Serenity or the 8.9 Swift.

I do not know the sheath proportion of the BlueWater Dominator and PMI Erratic 55g/m ropes, but my guess is that it is no more than 35%. Compare those two 7-fall ropes, at 55g/m, to something like the Petzl Zion, another 7-fall rope but one that weighs 66g/m and is 42% sheath. These three ropes have virtually identical dynamic properties, but the 66g/m rope will undoubtedly be much more durable.

Similarly, the [edit: second-] lightest current single rope, the Edelrid Corbie, measures 8.6mm and 51g/m -- comparable to Mammut's classic half rope, the Genesis, at 8.6mm and 48g/m. You could use the Corbie as a half rope, but with a sheath proportion of only 29%, it would not last nearly as long as the slightly lighter Genesis, which is 49% sheath.

Or suppose, as is often recommended nowadays, you were to buy a 9.4mm single. You could end up with anything from the aforementioned 55g/m BlueWater Dominator (if it were still available) to the 60g/m Edelrid Falcon -- two very different ropes.

Would you get a Sterling Nano 9.2 (53g/m) expecting it to be more durable than the aforementioned PMI Erratic 8.9 (55g/m), based on the Nano's larger diameter?

Or suppose you want an old-school do-it-all 10.5. You could get the outstanding BlueWater Accelerator (68g/m) or lug around the immortal but massive Mammut Superflash (72g/m); they are both 10.5.

So what do you think? Couldn't we come up with a better way of describing a rope than by its diameter?

Dr. Long Arm · · Unknown Hometown · Joined Jun 2013 · Points: 15
Deimos wrote:Similarly, the lightest current single rope, the Edelrid Corbie, measures 8.6mm and 51g/m
The Beal Opera is actually the lightest single at 48g/m with 37% sheath.
Deimos · · Unknown Hometown · Joined Apr 2010 · Points: 35
idahomike wrote: The Beal Opera is actually the lightest single at 48g/m with 37% sheath.
Thanks for the correction. The Opera is also a good contrast to the Genesis, since it is the same weight, but far less of it is sheath.
Doug S · · W Pa · Joined Apr 2012 · Points: 55

Great post! I've been looking closer at all the specs when purchasing ropes recently. I mostly consider impact force, elongation and weight. Been considering halves too, but a they're a little pricey just yet.

FrankPS · · Atascadero, CA · Joined Nov 2009 · Points: 276

I can see how it's easy to get "analysis paralysis" when buying a rope. Reviewing all the characteristics, coupled with price, could overwhelm someone. That's why I only care about a couple of things and make the purchase.

As evidence of that, when someone on MP asks for advice on "which rope to buy," they will get ten different rope recommendations. Once again, the perplexed buyer can be overwhelmed with choices.

I'm obviously not a rope connoisseur.

20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
Deimos wrote:For quite a while I have been wondering why climbers consider the principal characteristic of a rope to be its diameter. (Or, at least within a given dynamic rope classification -- single, half or twin -- diameter seems to be the characteristic that climbers focus on.) When evaluating a rope, you can look up how many UIAA-standard falls it achieved, what the standard-fall impact force is, and what the static elongation is. To get a sense of how durable a rope will be, you can look up what the sheath proportion is and maybe how many sheath bobbins are used and what the braid pattern is. And, of course, you can look up how much a rope weighs. If you review a bunch of these specifications, you will likely come to the conclusion that most of the properties of a good-quality modern dynamic rope (e.g. Beal, BlueWater, Edelrid, Mammut, PMI) can be estimated by knowing just the weight (g/m) and sheath proportion (%) of the rope. In general, a rope with a lower proportion of sheath will have better dynamic properties (more falls for its weight, lower impact force and a better relationship between static elongation and impact force) at the expense of reduced abrasion resistance. Also knowing the diameter provides a little more information -- a rope that is heavy for its diameter will undoubtedly have a stiffer feel. But knowing just the diameter of a rope tells you very little about it. So why do we focus so much on rope diameter? Wouldn't it be more useful to say "63g/m rope with 35% sheath" or perhaps "7-fall rope with 35% sheath"? An example of the problem of focusing on rope diameter is the confusion that ensues when comparing ropes like the original super-lightweight singles that weigh around 55g/m. The first of these, the BlueWater Dominator, measures 9.4mm. A later rope with virtually identical properties, the PMI Erratic, measures 8.9mm. Those are both 7-fall ropes. Other 8.9mm ropes -- the same diameter as the Erratic -- the Mammut Serenity and the Edelrid Swift, are 5-fall ropes; they weigh 52g/m. The 8.9 Erratic is much more similar to the 9.4 Dominator than to the 8.9 Serenity or the 8.9 Swift. I do not know the sheath proportion of the BlueWater Dominator and PMI Erratic 55g/m ropes, but my guess is that it is no more than 35%. Compare those two 7-fall ropes, at 55g/m, to something like the Petzl Zion, another 7-fall rope but one that weighs 66g/m and is 42% sheath. These three ropes have virtually identical dynamic properties, but the 66g/m rope will undoubtedly be much more durable. Similarly, the [edit: second-] lightest current single rope, the Edelrid Corbie, measures 8.6mm and 51g/m -- comparable to Mammut's classic half rope, the Genesis, at 8.6mm and 48g/m. You could use the Corbie as a half rope, but with a sheath proportion of only 29%, it would not last nearly as long as the slightly lighter Genesis, which is 49% sheath. Or suppose, as is often recommended nowadays, you were to buy a 9.4mm single. You could end up with anything from the aforementioned 55g/m BlueWater Dominator (if it were still available) to the 60g/m Edelrid Falcon -- two very different ropes. Would you get a Sterling Nano 9.2 (53g/m) expecting it to be more durable than the aforementioned PMI Erratic 8.9 (55g/m), based on the Nano's larger diameter? Or suppose you want an old-school do-it-all 10.5. You could get the outstanding BlueWater Accelerator (68g/m) or lug around the immortal but massive Mammut Superflash (72g/m); they are both 10.5. So what do you think? Couldn't we come up with a better way of describing a rope than by its diameter?
So what's the point here, that climbers fall for marketing nonsense just like most Americans? Of course they do. Just like people rank many cars by MPG or HP, climbers rank ropes by diameter. The less informed will always make poor decisions, and that's how it should be. Want to make the correct decision? Do your homework and dont be lazy. Most well-informed climbers are well aware of a rope's other specifications and they take them into account when buying a rope just as they take into account the diameter.
nathanael · · Riverside, CA · Joined May 2011 · Points: 525
Deimos wrote:For quite a while I have been wondering why climbers consider the principal characteristic of a rope to be its diameter. ........So what do you think? Couldn't we come up with a better way of describing a rope than by its diameter?
Your profile picture frightens me. The longer I stare into that eye for more frightened I become. Your gaze pierces my soul, it searches my innermost. Inside I'm screaming but the eye never blinks. This eye knows that I didn't cross reference the g/m, % sheath, % elongation, and # UIAA falls before purchasing my last rope. It knows and it is disgusted. I cower in self-loathing. Behind this eye is an encyclopedia of rope specifications and I have failed to measure up. I'm sorry.
Bill Kirby · · Keene New York · Joined Jul 2012 · Points: 480

I got a Bluewater Icon 9.1mm for its thicker sheath than other similar diameter ropes. Bluewater says the Icon and the Wave's thicker sheath gives the rope more durability. So yea diameters not everything.

Bill Czajkowski · · Albuquerque, NM · Joined Oct 2008 · Points: 20
Deimos wrote:For quite a while I have been wondering why climbers consider the principal characteristic of a rope to be its diameter. (Or, at least within a given dynamic rope classification -- single, half or twin -- diameter seems to be the characteristic that climbers focus on.) When evaluating a rope, you can look up how many UIAA-standard falls it achieved, what the standard-fall impact force is, and what the static elongation is. To get a sense of how durable a rope will be, you can look up what the sheath proportion is and maybe how many sheath bobbins are used and what the braid pattern is. And, of course, you can look up how much a rope weighs. If you review a bunch of these specifications, you will likely come to the conclusion that most of the properties of a good-quality modern dynamic rope (e.g. Beal, BlueWater, Edelrid, Mammut, PMI) can be estimated by knowing just the weight (g/m) and sheath proportion (%) of the rope. In general, a rope with a lower proportion of sheath will have better dynamic properties (more falls for its weight, lower impact force and a better relationship between static elongation and impact force) at the expense of reduced abrasion resistance. Also knowing the diameter provides a little more information -- a rope that is heavy for its diameter will undoubtedly have a stiffer feel. But knowing just the diameter of a rope tells you very little about it. So why do we focus so much on rope diameter? Wouldn't it be more useful to say "63g/m rope with 35% sheath" or perhaps "7-fall rope with 35% sheath"? An example of the problem of focusing on rope diameter is the confusion that ensues when comparing ropes like the original super-lightweight singles that weigh around 55g/m. The first of these, the BlueWater Dominator, measures 9.4mm. A later rope with virtually identical properties, the PMI Erratic, measures 8.9mm. Those are both 7-fall ropes. Other 8.9mm ropes -- the same diameter as the Erratic -- the Mammut Serenity and the Edelrid Swift, are 5-fall ropes; they weigh 52g/m. The 8.9 Erratic is much more similar to the 9.4 Dominator than to the 8.9 Serenity or the 8.9 Swift. I do not know the sheath proportion of the BlueWater Dominator and PMI Erratic 55g/m ropes, but my guess is that it is no more than 35%. Compare those two 7-fall ropes, at 55g/m, to something like the Petzl Zion, another 7-fall rope but one that weighs 66g/m and is 42% sheath. These three ropes have virtually identical dynamic properties, but the 66g/m rope will undoubtedly be much more durable. Similarly, the [edit: second-] lightest current single rope, the Edelrid Corbie, measures 8.6mm and 51g/m -- comparable to Mammut's classic half rope, the Genesis, at 8.6mm and 48g/m. You could use the Corbie as a half rope, but with a sheath proportion of only 29%, it would not last nearly as long as the slightly lighter Genesis, which is 49% sheath. Or suppose, as is often recommended nowadays, you were to buy a 9.4mm single. You could end up with anything from the aforementioned 55g/m BlueWater Dominator (if it were still available) to the 60g/m Edelrid Falcon -- two very different ropes. Would you get a Sterling Nano 9.2 (53g/m) expecting it to be more durable than the aforementioned PMI Erratic 8.9 (55g/m), based on the Nano's larger diameter? Or suppose you want an old-school do-it-all 10.5. You could get the outstanding BlueWater Accelerator (68g/m) or lug around the immortal but massive Mammut Superflash (72g/m); they are both 10.5. So what do you think? Couldn't we come up with a better way of describing a rope than by its diameter?
Why? Brevity.
Eric LaRoche · · West Swanzey, NH · Joined Aug 2011 · Points: 25
Jake Jones wrote:I determine my purchase by weight, impact force, falls, and price.
I do the same. diameter isn't even considered for me.
Mark E Dixon · · Possunt, nec posse videntur · Joined Nov 2007 · Points: 974

Save some brain cells and just get your "new" ropes from the dumpster behind the closest rock gym.

Marc801 C · · Sandy, Utah · Joined Feb 2014 · Points: 65

I buy ropes based on their feel and how pretty the colors are.

Daniel Winder · · Unknown Hometown · Joined Jul 2009 · Points: 101

Ropes get trashed. I buy the absolute cheapest dynamic rope available. No middle mark, dry coating, superproofing, bipattern, etc. As an added bonus (for me), the cheapest ropes are usually "thick" by today's standards (10mm) and I feel that thicker ropes in general hold up better to abuse. YMMV

Greg D · · Here · Joined Apr 2006 · Points: 883

Rope diameter is just one more spec for us to clench our butt cheeks and feel warm and fuzzy. And it is easy for most to understand. Grams per meter gives a little more info but takes two more brain cells to compare. Sheath percentage? I'm not sure one could make a blanket statement that more sheath equals more durability. Perhaps more resistant to cutting over sharp edges. But, you shouldn't be doing that in the first place. Remember when the "sharp edge resistant" ropes came out. Good marketing.

For me, I buy ropes based on impact force, grams per meter, soft hand, easily distinguished bi weave pattern even after it gets dirty, and pretty colors. Blue Water makes me feel warm and fuzzy. Quality company, quality ropes. Not always the cheapest. But, there are a lot of good ropes out there.

John Byrnes · · Fort Collins, CO · Joined Dec 2007 · Points: 392
Deimos wrote: So what do you think? Couldn't we come up with a better way of describing a rope than by its diameter?
It doesn't really matter.

Ropes are consumables -- they wear out. If you're a Real(tm) climber, you should go through a rope every year. If your a Real Sneaky(tm) climber, you'll wear out your partner's rope in a year. In either event, you get to try a new rope soon.

So stop obsessing about it. Buy a UIAA rope that feels good, feeds nicely through your device, is light weight (if you hike with it a lot) and the color matches your shoes.
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065

you cant tell how a rope will "feel" generally till you have it in yr hand and belay with it ...

for example the tendon ambition 10.2mm is one of the slickest 10mm+ ropes ive used when new (even when not dry treated) and feeds TONS easier than the maxim glider 10.2mm ... the former weights 67 g/m while the latter 66 g/m

mammuts and maxims tend to get stiffer with some use ... in many cases my infinity 9.5mm is less supple than a beal or tendon 9.7/9.8 despite being lighter and thinner ...

as to "diameters" theres a +/- 0.2mm variation permitted by the UIAA

2.2.2. Diameter.
The rope diameter specified on the hang-tag shall be within +/- 0.2 mm of the diameter
specified in 5.3.2. of EN 892:2004.


from beal ...

The measure of diameter is less precise than that of the weight.
It is thus better to compare the weights of ropes than their stated diameters.

also note that using the g/m is pretty useless as a measurement as to how heavy yr rope is ... what matters is the entire weight of the rope as different ropes manufacturers cut ropes to different lengths ..

;)

20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
bearbreeder wrote:what matters is the entire weight of the rope as different ropes manufacturers cut ropes to different lengths .. ;)
I could see how that would be your main concern when you're climbing moderates where the approach is the hardest activity of the day. But that is most certainly not what's most important to me. What matters to me is the amount of weight in my hand when I reach up to clip, and the weight tugging me down when I am at the end of the pitch pumped to hell. Total weight is meaningless there unless I am going to solo with a rope on, so g/m is what matters in applications where rope weight while leading is most important. As far as cutting ropes to different lengths, they dont differ by much, maybe 1m per manufacturer, which is like 60g--less than a quickdraw. Meaningless. G/m is perfectly acceptable.
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
20 kN wrote: I could see how that would be your main concern when you're climbing moderates where the approach is the hardest activity of the day. But that is most certainly not what's most important to me. I like to climb hard, and that means going for hard clips at times. What matters to me is the amount of weight in my hand when I reach up to clip, and the weight tugging me down when I am at the end of the pitch pumped to hell. Total weight is meaningless there unless I am going to solo with a rope on, so g/m is what matters in applications where rope weight while leading is most important. As far as cutting ropes to different lengths, they dont differ by much, maybe 1m per manufacturer, which is like 60g--less than a quickdraw. Meaningless. G/m is perfectly acceptable.
Have you ever weighted and measure a rope to see of its accurate ?

All the ropes came with claimed figures for weight/metre, fall rating and impact force. We checked the weight/metre figure by accurately measuring the rope length and then weighing it and we found that we got a different figure to the claimed one for all the ropes. After contacting the manufacturers we realised that this is because of very stringent requirements on how these figures are arrived at which makes it almost impossible to reproduce accurately, so we disregarded our own measurements for this figure. It should be added that, in our measurements, the ropes tested showed no major discrepancies relative to each other in what was claimed.

They found some 60m being spot on and another came in at 65m longer for example ...

It is customary for rope manufacturers to include a little extra rope, so a 60m rope will usually be a little more than 60m. We found that all the ropes we were sent measured a little long, which most people won't find a problem. One was spot on the claimed length and one other was 5m longer than the claimed length. Again, not really a problem unless you happen to be a victim of the following scenario:

You own a 60m rope that is really 65m but you don't know that. You climb a route and just get down to the ground when lowering. Someone else turns up and wants to do the same route and you tell them that a 60m rope is long enough. They lower off and end up 5m short - ouch!

Perhaps some standardisation in official extra rope length is called for? (Remember - always tie a knot in the end of your rope when lowering!)


ukclimbing.com/gear/review.…

I really wasnt aware that you climbed so hard that an extra CLAIMED 2 g/m mattered ... Why thats 60g on a 30m crazy hard sport pitch and the weight of a quickdraw ... Wait didnt u say that amount of weight was "meaningless"???

Anyways kudos to u fur being a KRUSHAH !!!

;)
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
20 kN wrote: Sigh, so cut off the extra 5m then if the weight means so much to you, dude, who cares. Like normal you are reinforcing your point based on some worthless Internet article instead of real experience. To say that someone should completely ignore the g/m value because the rope might be 63m instead of 61m is absurd, it highlights the clear lack of experience you have with regard to performance climbing. The specifications published by rope manufacturers are clearly not golden rules. Specifications change. Ropes get heavier with use. Impact force goes up with use. UIAA falls sustained goes down with use. On and on. However, fact remains that g/m is still the best way to compare the weight of various ropes, and a messily 2 or even 5m difference between rope lengths is meaningless in the big picture. No one ever failed to reach the base of the climb because they thought their rope was 7 lbs and it ended up being 7.09 lbs.
Sigh ... So u didnt actually weight and measure your ropes?

And yr complaining that i posted a source that did?

As i said that extra 2 g/m will definately stop you from sending that super jard 30m pitch !!!

Why thats 60g !!!! ... I take it you wear the lightest harness possible redpoint in yr gstring?

I totally applaud that yr sending climbs at such a level that 60g will make or break u

Make sure u take a dump before every redpoint attempt !!!

;)
20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346
bearbreeder wrote: Sigh ... So u didnt actually weight and measure your ropes? And yr complaining that i posted a source that did? As i said that extra 2 g/m will definately stop you from sending that super jard 30m pitch !!! Why thats 60g !!!! ... I take it you wear the lightest harness possible redpoint in yr gstring? I totally applaud that yr sending climbs at such a level that 60g will make or break u Make sure u take a dump before every redpoint attempt !!! ;)
Nice try, trying to flip this into a post about me after I called you out. Dude, no specification is going to be completely accurate--falls held, rope weight, dynamic elongation, impact force--they all vary a bit from rope to rope. But saying the g/m specification is worthless because it varies a tad from rope to rope, and implying that users need to physically weigh the ropes before buying them, is absolutely ridiculous. The g/m specification is more than sufficiently accurate for its purpose. The rope weight is going to change within a few uses from dirt absorption anyway.

I'll just leave it at this. Arguing with Beerbreeder is like arguing with the weekend warrior who climbs three 5.8 trad routes every other weekend but thinks he knows more about climbing than everyone else at the crag combined.
bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065
20 kN wrote: Nice try, trying to flip this into a post about me after I called you out. Dude, no specification is going to be completely accurate--falls held, rope weight, dynamic elongation, impact force--they all vary a bit from rope to rope. But saying the g/m specification is worthless because it varies a tad from rope to rope, and implying that users need to physically weigh the ropes before buying them, is absolutely ridiculous. The g/m specification is more than sufficiently accurate for its purpose. The rope weight is going to change within a few uses from dirt absorption anyway.
And my pont is simply its useless for determining how heavy yr rope REALLY is ...

Only a SCALE that you measure with can tell you that ... Anyone who has weighted gear can tell you that, maunfacturers specifiations simply may not be accurate

As for "making it about you" ...

You brought that on yrself when you went on about how u climbed so hard that you need those really light ropes and how a few claimed g/m mattered

I truly do applaud you for climbing so hard that u need to send it in a g string and one of those ~200g harnesses (this can really add up to a 100s of grams) ... Dont wear that beanie either

KRUSHING !!!

20kn wrote:I'll just leave it at this. Arguing with Beerbreeder is like arguing with the weekend warrior who climbs three 5.8 trad routes every other weekend but thinks he knows more about climbing than everyone else at the crag combined.
And ill just leeave this here

20 KN will simply brag about how he climbs soooo hard that he cant send with a few extra grams ...

On his first response tooo !!!

I dont resent the climbing moderates, lol ... But i do breed my bears every good day!!!

;)
Guideline #1: Don't be a jerk.

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