metoulis

[john]

So I was going to buy a set of the new master cam but realized that in the smallest sizes, which is the sizes I want most, they have 40% less range than Aliens. I alway new they used a smaller cam angle then other companies and do not use double axel, as BD does (patented) so I new they sacrificed range for what they call greater holding power, which is crap as placements fail before max breaking strength is reached due to rock crumbling and failure. I really like the look of them for small sizes but a cam with a range of only 3 ish mm is limited for free climbing. In larger sizes the % difference is smaller and less important inherently but I bet they have the same problem as aliens in larger sizes which is stability. rant done.

my choice remains
BD .5 up
alien black - red

[Fred]

John: check out http://www.rockclimbing.com for recent gear review on the Master Cams.

[granite_grrl]

John, Nathan (chossmonkey) ripped three seemingly well placed cams from a crack last fall and took a grounder. The rock did not fail, it was just a parallel crack in limestone.....the cams didn't have enough holding power and slid out.

He was using Black Diamond cams BTW. Not saying that Metolius cams would have saved his ass (literaly, you should see the scar! ), but I am very very happy to have them on my rack. I can't wait to check out the new Master cams.

[chossmonkey]

Think about "holding power" like this.

[john]

I have done finite element force analysis on specifically BD #3, 4 years ago for graduate work. I gaurentee a cam in limestone did not pull out due to lack of holding power, it is physically impossible with the forces generated in a fall.

My point is that a properly placed cam is unable to fail in any placement due to holding power issues alone. It can however, fail due to a million other reasons, most commonly according to most published cam research, micro rock failure leading to placement slippage. Even the slightest placement slippage can generate an acceleration greater than the expansion spring acceleration of a cam ie. essentially the cam cannot regain purchase prior to pull out. This failure mode is most common in either soft rock, or flaring placements.

My point is just that metoulis's argument for utilization of a smaller cam angle for the purpose of greater holding power at the expense of less range is BS. Granted in a lab their argument may hold water for larger cam sizes, but in the smaller cam sizes such as their smallest cam, with a range of only 3.5 mm, (remember max holding power is at 80% closure) its practical useful range is non existent. This problem is compounded in free climbing situations where placement time is critical. Additionally, for small cams, greater force is placed on the rock due to surface area deceases when compared to larger cams. This means that a small cam if not placed exactly perfectly has a much larger chance of pull out than an equivalent quality placement of a large cam and since Metoulis reduces its expansion range in return for supposed holding power, ones likely hood of a quality placement is reduced. In my opinion the lack of range in real world climbing is a detriment when compare to its competitors.

In larger sizes the expansion range difference is not nearly as significant, but from the looks of the specs of the larger models they will likely suffer, as aliens do, from walking as compared to the the larger width BD's. Metoulis short sling length also compounds this from the reviews I read.

All in all, I bet they are still quite good and most people will never know the difference. I have been looking to replace a couple older sets of aliens with something new but with the same benefits; however it is clear to me Metoulis made a good effort but fell short.

cheers

[granite_grrl]

So basically you don't like Metolious cams and you want to start an argument about how Aliens are better. Well, if there's one thing I've learned it's not to waste my time arguing with religious fanatics or Alien lovers.

Personally, I feel that CCH is a shoddy company and even if they've fixed their quality problems they do not deserve my buisness. I also hate the way C3s feel and would not bother buying them from BD, and any C4 below a 0.75 is too wide for my tastes. I have a set of TCUs and I love them.

I have not noticed these vast expansion range issues you're complaining about when ever I've switched over to a partner's Aliens in the past. I think your mind was already made up about your Aliens.

[*Chris*]

Screeeee (the sound a can of worms makes when opened)

John,
I follow your logic above for the most part. However, there's one statement which I can't rectify with anything that I think I know about cams:

(remember max holding power is at 80% closure)

Isn't the whole point of a constant-angle cam design that it generates the same outward forces at all positions along it's expansion range??? I agree that 80% closure sounds about right for an ideal placement. But... doesn't this have more to do with maximizing a safety buffer against walking to a tipped-out position while still being retrievable?

[Shawn B]

So basically you don't like Metolious cams and you want to start an argument

Isn't this the main purpose of all internet forums??

about how Aliens are better. Well, if there's one thing I've learned it's not to waste my time arguing with religious fanatics or Alien lovers.

Well don't argue with me then 'cause i'm religiously fanatic ABOUT aliens.

Personally, I feel that CCH is a shoddy company and even if they've fixed their quality problems they do not deserve my buisness.

So don't buy them.

I also hate the way C3s feel and would not bother buying them from BD

So don't buy them.

, and any C4 below a 0.75 is too wide for my tastes.

So don't buy them.

I have a set of TCUs and I love them.

Glad you are able to find something you like.

I have not noticed these vast expansion range issues you're complaining about when ever I've switched over to a partner's Aliens in the past.

Thought you thought they were a shady company....why do you use gear made by a shady company??

I think your mind was already made up about your Aliens.

I don't think John's mind was made up at all. All his points seem thoroughly thought out and he gives what I would call a very well educated opinion as to his views. I won't necessarily always agree with everything John says but I certainly put more value in his opinions and observations than I would a lot of other people.

All that said, my favourite piece of gear is the one which last saved my butt. I personally prefer BD from .5 and up sizes and I carry a set of tcu's and a set of aliens. I love the aliens and got them before the quality control issues. Would i buy more...probably not. Although i still do think the design is the best small cam out there. Looking forward to playing with a new master cam before making up my own opinion.

[Fred]

now now kids lets play nice

I must add that although Rebecca came on a bit strong I do see her point in that John is an Alien fan and always has been. He was even buying mine off of me as news was coming out on the failures. That's pretty dedicated. hehe sorry John.

On another note. To compare the two is where you guys are wrong IMO. The two companies are different and the product is different. Each should be in its own respective thread. Too many have been anticipating this new Metolius cam release as the Alien replacement when it's obvious by now that this is not the case.

[granite_grrl]

On another note. To compare the two is where you guys are wrong IMO. The two companies are different and the product is different. Each should be in its own respective thread. Too many have been anticipating this new Metolius cam release as the Alien replacement when it's obvious by now that this is not the case.

Fred, you're correct that I came off a little too strong, and I’m sorry. Too much of the special olympics on RC.com I guess .

I agree that each should be considered separately. The valid discussion brought up by john is muddled by his comparison to Aliens, and that's what got my back up. In the end Metolious users don't really notice this lack of expansion range and would rather carry 5 small cams than 4. Like I said before (though I'm loath to bring up another cam again) I have used Aliens a decent bit, and was in fact going to bet a set initially, and have never noticed the difference in expansion ranges compared to TCUs. So to me his argument seems moot.

But I am genuinely curious about John's research into cams and holding power. I understand the concept of the springs not reacting fast enough when the rock starts to break. But I'm wondering about situations where the initial force generated wasn't sufficient to hold. Instead of bringing up Nathan's accident again, I'll use the example of a cam in fairly smooth, very compact rock, but lets say the rock is wet. Would holding power adversied by companies make a difference then?

And, Shawn, it is personal preference about which cams you prefer. Good for me, good for you. But no, I will not argue with you about it. Let’s bring this conversation back to hold power vs expansion range of cams and try to stay away from the cam comparison conversations.

[Shawn B]

On another note. To compare the two is where you guys are wrong IMO. The two companies are different and the product is different. Each should be in its own respective thread. Too many have been anticipating this new Metolius cam release as the Alien replacement when it's obvious by now that this is not the case.

But Fred, that is what John is trying to do. He is looking for replacements for his aging aliens. And because he loves his aliens, he is looking for something very similar...and thus will obviously compare the new option to his truely loved aliens. Can't blame him either. imo the aliens is the best designed small cam. Not the best manufactured or quality...just the best design. And I think a large percentage of climbers would agree and this is shown by the fact that most have been waiting for an "alien replacement" since the quality issue started. All that said...and not to compare...but i actually prefer the 00 and 0 tcu to the black and blue alien. i find in those small sizes the stem of the alien is not stiff enough to jam into small places like where you would use these pieces. Then again, maybe i just don't know how to place them (i'll beat someone else to that comment). And I do agree with granite grrl that in that small a size range is probably such a small difference it won't be an issue. One thing about the master cam that does seem to be a negative is the horizontal placement. Again...will have to wait and play with one prior to forming my decision.

Wow...two posts in one day. i'll go away for another few months now.

[chossmonkey]

My point is just that metoulis's argument for utilization of a smaller cam angle for the purpose of greater holding power at the expense of less range is BS.

You are entitled to your opinion but I think you are still missing the point/function of "holding power".

I have no doubt that if the cams catch and hold in the rock the cam angle has little to do with the failure. The thing is they need to catch. Cam angle (a.k.a. holding power) has EVERYTHING to do with that. Especially in less than ideal placements such as slick or wet rock.

The cam angle on Aliens is 16 degrees. For comparison Wild Country uses 13.75. If I'm not mistaken they patented it, I can't find the patent reference right now. I also can't find the angles for BD or Metolius. I'd be willing to bet Metolious is around WC maybe just below them. And I'd guess BD is somewhere between CCH and WC. Anyhow, here is what WC has to say about cam angles...

So what is the perfect camming angle? To answer this question one needs to go back to the friction test. Aluminium slips on granite at 18° but if this angle were used the device would be at its absolute limit of friction in a parallel granite crack and would not work in a flared placement or in say, a limestone crack. The angle needs to be reduced a little.

Ray Jardine originally used 15° on his prototype Friends, which was good on granite, the rock he was familiar with, but didn’t work as well in some rock types he climbed on in Britain in 1977. After much testing, Ray and Wild Country decided on 13.75°, an angle that worked well on most rock types and allowed for use in quite flared cracks in such rock as granite and gritstone.

Maybe I'm way off base and I'm just buying into the propaganda?

I'm not the only one who bases it on more then just what the cam companies tell me. Years ago I met and climbed with a guy who worked in the climbing industry. He saw my rack and said "WHOA!! you trust those things?" when he saw all my Camalots. I asked why not? He told me he new a number of people who would never climb on them because they had been known to pull out of perfectly parallel cracks. I shrugged it off as typical climber "not my brand" poo pooing. I have since had a few friends pull good cams and have heard of other people.

Fast forward to many years, and I got to experience first hand what I had been warned about. Talking to others, it seems most good cams that have pulled out have been BD. Perhaps its their overly large market share? One friend of mine saw a WC cam pull out when they were using it to climb a big concrete overhang. In all fairness I haven't heard of well placed Aliens pulling, but then again the most popular Aliens are in small sizes where rock failure and bad placements are usually suspected first and nobody expects a good cam to just come out.





YMMV

[Murph]

Just grid bolt everything... problem solved.... I'm joking

[Fred]

Just grid bolt everything... problem solved.... I'm joking

oui! parfait! likes wez do back homes...

[martha]

I personally like the fact that BD has come out with biners in all the colors of their cams to i can completely color code my rack. Even better when it matches the stripes on my rope and the hat I just knit for the particularly chilly spring we are having.

[john]

Norfolk,

Theoretically yes, cams do use a constant cam angle. BD achieves its increased range, yet still keep holds to this theory by utilizing a patented double axle design. Other companies are stuck with range determination directly related to the chosen cam angle and can't squeeze any additional range increase out of a cam except by increasing cam angle, ie decreasing holding power.

More than just this leads to a quality placement ie max holding power! This idea is what lead to metoulis original range finder idea. A cam is not as safe outside of a certain expansion range despite constatn cam angle. The details of what exactly determines this is quite complicated in real world situations. However, this is not new news, metoulis's website explains this without details, see below for interest. Notice though they don't attempt to explain exactly how they choose the range finder % expansion range.

If you dig around the net geek physics discussions you can find info on this. The problem is in out of lab setting there are so many variable and inevitably you need to make assumptins and generalizations for analysis. But generally (again I have seen arguemtns about the exact %) cams are best placed near mid expansion from say 40-80% closed with it better closer to 80%. I could list a bunch of reasons, but really they could all be argued.

What is comes down to somewhat is static vs dynamic force analysis. But practicably you can see for yourself that when you leave a cam in a crack at 10 percent closure versus 90% closure the cam is far more likely to walk at 10%. In a situation when you fall (and yes I mean in the fall itself), a climber has a trajectory which pulls both outwards and downwards and every angle in between on the cam. This action twists the lobes as it tilts and any uneveness in the crack and cause any under-cammed lobes to both slip, and also potentially in a 10% closure, become 0% (not alot of margin of error at that % closure) hence hold no force, where as in a 90% case you could open up the cam more and still be safe (if slippage acceleration was not great). This goes back to my orignail point that expansion range is hugely important in small cams with little range to begin with!

There are a bunch of interesting points surrounding analysis of this issue, some complex some simple but all interesting to discuss. Personally I only care about the issues which have a measurable affect on real climbing performance. In samll cams cam angle and expansion range do. I would love to replace my aliens but no one makes a good a cam Except quality wise



From Metoulis:

"It all started with a phone call and a simple question. An operator of a guide service called to get our recommendation on what he should be telling his guides about the safe working range of our camming devices. We had, of course, answered this question many times before. But we realized that many people just didn’t thoroughly understand the range and dynamics of camming devices. No one had ever truly addressed the issue; and it definitely struck a chord. We quickly realized that as a manufacturer of cams, we were in a unique position to enlighten the masses on this somewhat complex topic. We went back and forth about how best to explain things in simple terms. Then we had the revelation . . . we could just put a color-coded indicator on each and every cam. Voila--Range Finder was born. The beauty is that this visual-feedback system (colored dots) is so simple that it requires almost no explanation."

"We are really pleased with the way the Range Finder feature has made placing cams simpler and safer. The Range Finder is a brand-new feature on our cams that helps you assess placement quality, thereby making our cams safer and easier to place. It is a powerful tool to let you know where you are within a cam's range (from tipped out to maximum retraction and everywhere in between). In the history of camming devices, nothing like the Range Finder has ever been introduced. However, it is no panacea. It's still up to the individual to assess his or her own skills, rock quality, placement quality, or whether the rock is wet or dirty, flaring, etc. Like all things, there is no substitute for experience. In critical situations, always double or triple-up protection points to increase your margin of safety! Range Finder means no more second-guessing your placements - red means stop, yellow means caution, green means go!"

[*Chris*]

Good analysis John. You've verified what I wrote above; that the ideal placement along the range has more to do with creating a safety buffer against movement than it does holding power. It is certainly clear now.

[STeveA]

I think this discussion points out why I would much rather trust a solid nut placement than a cam placement. The physics for the nuts is fairly simple. The times that I have had to retreat and rappel from a single piece it has always been a paasive device, partly because I'm cheap, but mostly because I trust them.

[granite_grrl]

Good analysis John. You've verified what I wrote above; that the ideal placement along the range has more to do with creating a safety buffer against movement than it does holding power. It is certainly clear now.

What I understood is that he is saing that if you're climbing on rock that commonly breaks or commonly getting poor placements then you should consider cams with a larger cam angle because its more forgiving.

I would still like to hear his explaination on how holding power counts for squat in other situations (please refer to chossy's well outlined post).

[STeveA]

If you go through the physics for a cam using the logarithmic curve (such as Friends) then the holding power is related to the camming angle and the coeffiient of friction of the cam against the rock. The camming angle is a function of the design, although it will vary in flaring and narrowing cracks and is only accurate for parallel sided cracks. The coefficient of friction will vary with rock type and climate/environmental conditions.

Theoretically, the position of the cam is irrelevant since it has the same holding power whether it is 10% cammed or 90% cammed. From a force diagram the only thing that will cause the cam to slip is when the tangent of the camming angle is greater than the coeeficient of friction. For friends the tangent value is 0.25. Aluminum on granite has a coefficient of friction of 0.45 so everything is good (theoretically). If the rock is wet or lichen covered then the value of the coefficient will change. For different type of rock you will get a different coefficient of friction (maybe this value should be added to guidebooks for local areas and weather conditions).

Therefore, what will really determine a good placement, assuming the coefficient of friction is high enough, is the quality of the rock. If it breaks, fractures or crumbles then the cam will slip. A moving cam now encounters a kinetic coefficient of friction rather than a static one, and that is almost always lower. Therefore, once the cam starts to slip it will probably keep on slipping. Also, as noted before if the rock breaks and the cams expand there is a possibility of losing contact with the rock due to full expansion and then there is no camming action. If you have a BD it may jam like a nut.

A big problem with an overcammed device is that the range left to help with removing the cam is limited and you may have a stuck Friend.

We should conduct some tests to determine the coeeficient of friction for Welsford rock.

[*Chris*]

We should conduct some tests to determine the coeeficient of friction for Welsford rock.

That would make a pretty cool project for some engineering student. I propose tests using:

Dry Welsford Granite
Wet Welsford Granite
6061-T6 Aluminum (soft - Aliens)
7075 Aluminum (harder - Black Diamond)

For extra credit, it would be interesting to see the impact cam lobe teeth have on the COF. For super-extra credit... add lubricant until the cam is ineffective. Since I'm not an engineer, I must ask; how easy/hard is it to measure the COF between two surfaces?

[STeveA]

It would be pretty easy to set up an experiment on a slope and add weight until the object started to move. We are not trying to test the pull out of the gear, just the coefficient of the rock in various conditions. If we include different rubber on rock into the test we could try to figure out when your shoes will slip etc. Would be a fun project for an engineering student.

[Fred]

Recommend we proceed straight to human testing to minimize R&D costs.

[chossmonkey]

Recommend we proceed straight to human testing to minimize R&D costs.

Being the crash test dummy is no fun when things go wrong.


I'm happy you are volunteering. I've had my fill.

[chossmonkey]

If you go through the physics for a cam using the logarithmic curve (such as Friends) then the holding power is related to the camming angle and the coeffiient of friction of the cam against the rock. The camming angle is a function of the design, although it will vary in flaring and narrowing cracks and is only accurate for parallel sided cracks. The coefficient of friction will vary with rock type and climate/environmental conditions.

Theoretically, the position of the cam is irrelevant since it has the same holding power whether it is 10% cammed or 90% cammed. From a force diagram the only thing that will cause the cam to slip is when the tangent of the camming angle is greater than the coeeficient of friction. For friends the tangent value is 0.25. Aluminum on granite has a coefficient of friction of 0.45 so everything is good (theoretically). If the rock is wet or lichen covered then the value of the coefficient will change. For different type of rock you will get a different coefficient of friction (maybe this value should be added to guidebooks for local areas and weather conditions).

Therefore, what will really determine a good placement, assuming the coefficient of friction is high enough, is the quality of the rock.

Nice post Steve. I think you did a much better job of me trying to explain.

[STeveA]

Good idea Fred, we could add skin on granite as one of the parameters. Should we start a list of people we want to be volunteered? I will chip in $5 for the cause.

[*Chris*]

I'll add another hypothesis that human blood in a crack reduces the COF significantly more than water... but I don't volenteer.

[STeveA]

How about if I up the ante to $6?

[Makwizard]

I am currently conducting research at Duke University to analyze and redesign cam lobes. The end goal is to improve a cam's ability to hold in soft rock and flaring cracks. I have just begun my research but will be continually posting updates of my findings on my cam research page.

Thanks.

[chossmonkey]

I am currently conducting research at Duke University to analyze and redesign cam lobes. The end goal is to improve a cam's ability to hold in soft rock and flaring cracks. I have just begun my research but will be continually posting updates of my findings on my cam research page.

Thanks.

I'd be much more interested in a study of cam angle in relation to holding power/initial grab in rock with less friction. I think there is a direct correlation with tracking in soft fine grained rock and very parallel cracks(i.e.the Creek). I think that the tracking is more because of the parallel nature of the cracks than being soft. It would be cool to see some actual facts as to what is the true cause.

Failure in flaring cracks is similar to failure to frictionless rock since it increases the cam angle and decreases the friction for initial engagement of the cam.