Sub 10mm rope opinions wanted

Marc Horan wrote: Would you say, as an apparent expert, that a rope with a higher elongation would have a lower impact force? Is it safe to say there is a direct correlation between those two values? --Marc

I'm not an expert on ropes. An expert would be able to explain how the construction of real ropes accounts for the weak correlation among parameters that intuition suggests should be strongly correlated. Indeed, if climbing ropes were ideal springs, a thicker rope made of the same material would have a larger rope modulus. Therefore, it would elongate less and exert larger forces. Climbing ropes, however, are significantly different from ideal springs.

Coming to your question, the correlation between elongation (both static and dynamic) and impact force is rather weak (-0.36 and -0.44) but at least it has the right sign (we expect impact force to decrease with elongation), and is better than the abysmal -0.13 we find for the correlation between diameter and impact force. Said otherwise, differences in elongation explain only in part differences in impact force.

(For the layperson, correlation coefficients go from -1 (strong negative correlation) to +1 (strong positive correlation). Absolute values close to 0 indicate weak correlation.)

Edit: I was composing my message when Richard posted his. Yes, I agree with him.

brenta wrote:I'm not an expert on ropes. An expert would be able to explain how the construction of real ropes accounts for the weak correlation among parameters that intuition suggests should be strongly correlated.

Ok, you're not an expert, but you appear to be significantly more knowledgeable than me, and I'm gonna pick your brain for a minute, if that's cool.

brenta:
Indeed, if climbing ropes were ideal springs, a thicker rope made of the same material would have a larger rope modulus. Therefore, it would elongate less and exert larger forces. Climbing ropes, however, are significantly different from ideal springs.

brenta wrote:Coming to your question, the correlation between elongation (both static and dynamic) and impact force is rather weak (-0.36 and -0.44) but at least it has the right sign (we expect impact force to decrease with elongation), and is better than the abysmal -0.13 we find for the correlation between diameter and impact force. Said otherwise, differences in elongation explain only in part differences in impact force. (For the layperson, correlation coefficients go from -1 (strong negative correlation) to +1 (strong positive correlation). Absolute values close to 0 indicate weak correlation.)

Ok. I think that I understand this, for the most part; it's possible my next question will prove otherwise though. Say you were to make two different ropes with the same exact materials (just the core, for simplicities sake) and the same exact manufacturing process; one is 8mm and one is 12mm. You then compared the characteristics of each rope in a matrix, might that change the outcome, or no?

Marc Horan wrote:Say you were to make two different ropes with the same exact materials (just the core, for simplicities sake) and the same exact manufacturing process; one is 8mm and one is 12mm. You then compared the characteristics of each rope in a matrix, might that change the outcome, or no?

I think it would change and show higher correlations between those parameters we expect to see strongly correlated. How much would it change? I don't know.

I'll give you another example, which is far from perfectly fitting to our case, but may help one to illustrate the difficulty of guessing the answer. Suppose you built two engines with exactly the same architecture, but such that one had exactly twice the displacement of the other. Would the larger engine deliver twice the power of the smaller one?

Gotcha; Makes sense. I think it's actually a great analogy.

Thanks for the analysis, it's quite interesting, actually.

--Marc

Brenta, thanks. Your info was very informative. I was hoping to get more personal feed back i.e. which rope you use, your buddies use, and the impression you got from these ropes. What I'm hearing is Mammut and Beal are making the best skinny rope for trad. Maybe around 9.6 give or take .1? Anyone out there like Mike who digs a 9.2? 9.2 seems like it would wear out fast getting pulled around on routes that wander.

I myself have used "skinny" ropes almost exclusively. I like being able to save the weight on long approaches and long routes. I have fallen a number of times on long trad routes, and of course lived to tell. I use a Mammut 9.1, and before that a 9.4. I do replace it more often than my 10.6 crag rope however. My advice is to save the weight that a thinner rope offers, and take care of it.

Brenta, I think the factor you need to add to your equation is the core to sheath ratio. Ropes that have a higher percentage of sheath also tend to have higher impact forces. So it comes down to a trade off generally between impact force and durability.

Mammut ropes are workhorses and seem to last a long time, they also have the some of the highest impact force ratings.

Beal ropes have very low impact force ratings, but my experience is that their sheaths fuzz up a lot faster than other ropes.

Below are reviews of some sub 10 ropes I currently have or have used before:

9.1 Joker - personally I think the name says it all, took a friends up 2 days on the Diamond, and by the second day ( 3rd total on the rope) It looked and felt worn. Also had major sheath slippage (one end was all bunched for 3 feet). Wouldn't ever buy one.

9.4 Blue Water Dominator - Silky smooth and tough as nails, I love this rope.

9.4 Beal Stinger - Have owned several of these ropes, and will buy more. They fuzz up but last a long time, especially the golden dry ones.

9.7 Beal Booster - Friend has one currently, has been up 8 alpine routes this summer and we have been hammering on it sense, still looking good!

9.8 BlueWater Slimline Elite - Was disapointed with this rope, it did not meet my expectations for durability. After a 20 pitch solo day and 2 NIAD days it looked beat up and the sheath had slid on one end making it mushy. Still climbing on it and hoping it will "Go the distance", but the jury is still out.

9.8 Mammut Tusk - Owned several of these ropes and they worked well for the cost. Probably your best value of the ropes listed and should last for a while.

As for the "Ideal size" I think it comes down to preference and experience. 9.2 is a bit scary at first if you are used to 10.2 ropes, but they sure are lighter. I like 9.4 ropes for a nice tradeoff between weight and durability, but you will see snags in the sheath if you are falling on them. 9.7 or 9.8 ropes are a bomber compromise.

Yeah, I'm not digging the wear-life on my Beal Joker. I only use it for very long approaches because it is dying fast. Ropes usually last me several seasons, but this one will be measured in use-days.

Joey Wolfe wrote:Brenta, thanks. Your info was very informative. I was hoping to get more personal feed back

You are welcome. I've had a Beal Joker 9.1 for a little over 2 years. It's still in good shape, but I'm afraid that only means that I don't use it enough.

Kevin Stricker wrote:I think the factor you need to add to your equation is the core to sheath ratio. Ropes that have a higher percentage of sheath also tend to have higher impact forces.

Unfortunately, manufacturers are not uniform in reporting about the sheath percentage. Beal, for instance, gives the number of bobbins, with more bobbins implying a thinner sheath.

It would ceratainly be interesting to plot impact force against sheath proportion, though there may be surprises. For instance, the Joker has a 48-bobbin sheath, while the Stinger has a 40-bobbin sheath, and yet it has a slightly lower impact force.

A back-of-the-envelope computation suggests that the two ropes have about the same core cross-section, with the sheath percentages being 32% for the Joker and 40% for the Stinger. My estimate could be wrong, but if it weren't, there goes the theory that differences in impact forces are explained by differences in sheath percentage.

Holy shit this thread is making my sphincter hurt!

I need a reach-around for pete's sake.

9.7 Arete from PMI - one of the best ropes I've ever used. (for that matter, the 10.2s from PMI are all-around f-n fantastic also)

I have an Edelweiss Ultralight (9.9mm), bi-color, Super Everdry, with the Perdur treatment (to resist friction). Sexiest rope I've ever had. Compared with 2 other Edelweiss ropes I've owned (10.5 and 10.2mm without Perdur), the Ultralight has been the best, in my opinion. It's noticeably lighter (not incredibly lighter, though), more friction resistant, less prone to twisting, and feeds through my Reverso better when it's setup to auto-lock and belay from above. I took it canyoneering in Zion and it didn't absorb much water at all, which was nice during the 2hr hike out. It's also plays nice with a Gri-Gri. $187 at either GearExpress or Bent Gate

I've asked around outside of MP.com and most people have complaints with the durability of a Beal rope. It sounds like Beal ropes are a nice rope for one-pitch bee-line sport climbs, which is not what I'd be using it for. I found a good deal on a Mammut Infinity 9.5( spadout.com/store.php?stpr_… ) and at 58 grams per meter it is 780g lighter than my Edelweiss Axis(WHOA!). I'll probably wait till after Xmas, so more input would be useful.

Joey Wolfe wrote:Anyone out there like Mike who digs a 9.2? 9.2 seems like it would wear out fast getting pulled around on routes that wander.

I'm a big fan of the Bluewater Dominator. 9.4mm, but, look at the gram/meter weight, as I think there isn't a consistant way to measure rope diameter.

I got excellant wear out of mine, with a gob of TRin' and rough use, and, its still in pretty good shape. Didn't fuzz out, no sheath gobies, etc. Hand was great. I bought another one...

But, my main climbing cord right now is a Mammut Serenity, 8.9mm. Great hand and seems to be wearing very nicely (as in, not much sign its hardly been used, in over a 100 pitches).

I mostly climb trad routes, do some sport, and don't really "work" sport routes, so, I might not get the same type of wear that someone else might get on their rope (ie, a bunch of falls). Also, I'm a bigger feller. I like me a skinny lead rope, especially for wandering trad pitches, as I think it feeds easier through gear with lower friction and makes a difference on longer pitches. Plus, lower volume and weight in my pack for longer approaches and egresses.

Anyhoo, cheers.