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Ultralight Ice Screws: BD vs. Petzl


Slogger · · Anchorage, AK · Joined Mar 2015 · Points: 80

Well I'll throw my $.02 in here. I've traded away all my Petzl screws for their BD equivalents. Have got a few of the new BD UL as well. I got tired of turning and turning the the Petzl screws and not having the rounded threads bite. This was pretty much only in cold, dry ice. Good ice, everything works. Really digging the BD UL's now that I've got them though and couldn't be happier to have gotten rid of my steel Petzl screws.

One thing I was concerned about on the BD UL's was the wire handle but as stated above, it seems to be a non issue, plenty strong.

Robert Hall · · North Conway, NH · Joined Aug 2013 · Points: 16,348

Was up on some pretty "soggy" ice this weekend. My regular STEEL Blk Diamonds clogged up and wouldn't thread; I had one Petzl aluminum and it went in like a charm.  

Later, at the climbing shop I looked carefully at both the BD and Petzl aluminums.  I noticed that the threads of the Petzl's were rounded all around, while the BD's had a "flat" upper surface to the thread, just as the steel BD's threads are.

Tests have shown that it is the resistance of the threads to pulling out during a fall that gives ice screws their "holding power". This is why an ice screw should be placed pointing slightly downwards...very counter intuitive.  It would seem to me that a thread that has a flattened "upper portion" to it would be more resistant to pulling out of ice than a thread that is rounded and smooth all around.

Has Petzl ( or anybody) done testing of the relative holding power?  Almost all of the ice screw testing I can recall was done on BD-type screws.

Briggs Lazalde · · Unknown Hometown · Joined Sep 2017 · Points: 0

Just curious.....would spraying your screws inside and out with a water repellant like scotchgaurd help to shed ice and not clog the screw?

Gavin W · · Langley, BC · Joined Feb 2015 · Points: 181
Briggs Lazalde wrote: Just curious.....would spraying your screws inside and out with a water repellant like scotchgaurd help to shed ice and not clog the screw?

I would imagine that ice is too abrasive and would wear the coating off the first time you used the screw. Just think about how easily the DWR coating wears off on your WPB jacket. 

Briggs Lazalde · · Unknown Hometown · Joined Sep 2017 · Points: 0
Gavin W wrote:

I would imagine that ice is too abrasive and would wear the coating off the first time you used the screw. Just think about how easily the DWR coating wears off on your WPB jacket. 

True. What about teflon?  I dunno. Though I havent had much problem with ice sticking, sounds like its not fun when it does happen

zoso · · Unknown Hometown · Joined Jun 2007 · Points: 495
Robert Hall wrote:...I noticed that the threads of the Petzl's were rounded all around, while the BD's had a "flat" upper surface to the thread, just as the steel BD's threads are.

Tests have shown that it is the resistance of the threads to pulling out during a fall that gives ice screws their "holding power". It would seem to me that a thread that has a flattened "upper portion" to it would be more resistant to pulling out of ice than a thread that is rounded and smooth all around.

Had the same thought over 10 years ago when it was first said to place screws thusly.  I'd be interested if there is any info on this.  

It also stands to reason that screws should be threaded for their entire length as well. 
Luc-514 · · Montreal, QC · Joined Nov 2006 · Points: 9,489

A friend made a recent finding on one of his screws

Robert Hall · · North Conway, NH · Joined Aug 2013 · Points: 16,348

1)  Re' coating insides:  (I do it,: WD-40, Teflon spray, etc. Sure you have to re-apply every so often. )  Yes, I think this helps, especially in "shaking out" ice from a screw that's just been removed; but the situation I had was the first 1/2 inch just clogged up.

2) Looks like Luc's friend has a cracked screw....manufacturer should replace that !

rocknice2 · · Montreal, Quebec · Joined Nov 2006 · Points: 3,129
zoso wrote:

Had the same thought over 10 years ago when it was first said to place screws thusly.  I'd be interested if there is any info on this.  

It also stands to reason that screws should be threaded for their entire length as well. 

Someone wrote a paper on this years ago. I think that paper is what changed everyone's mind about placing screws. 

https://www.needlesports.com/content/ice-screw-placement.aspx
rocknice2 · · Montreal, Quebec · Joined Nov 2006 · Points: 3,129
Sam Sala · · Denver · Joined Oct 2013 · Points: 40
Luc-514 wrote: A friend made a recent finding on one of his screws

Curious what caused that crack. I would guess some sort of expansion of ice, internally. Was it noticed when the screw was pulled from a placement, or later on (so no telling when/how it happened)?

Eric and Lucie · · Boulder, CO · Joined Oct 2004 · Points: 140
Luc-514 wrote: A friend made a recent finding on one of his screws

I've seen the same cracks on two other Petzl aluminum screws (one was my own; I had it replaced by the store).  My guess is that the steel tip is sometimes a bit tighter in the aluminum main tube (manufacturing variability), and then, if the screw gets very cold (or repeatedly very cold, i.e. fatigue), the difference in thermal expansion between the steel and the aluminum sometimes ends up overloading the aluminum tube and cracking it.  Keep an eye on them...

erik wellborn · · manitou springs · Joined Apr 2008 · Points: 355

I've been using both Petzl and BD ultralights this season. Usually on lead on minimally climbed ice that hasn't been hacked out. Conclusions? Really couldn't tell a difference. Both start really well, even on hard brittle ice, and both can get "sticky" in wet, cold ice.

Eric and Lucie · · Boulder, CO · Joined Oct 2004 · Points: 140
erik wellborn wrote:...Both start really well, even on hard brittle ice, and both can get "sticky" in wet, cold ice.

I have not tried the BD version, but I agree.  We were on Bridalveil last weekend and the aluminum Petzl screws were really remarkable, both starting and drilling.  But that route is incredibly dry and cold this season (actually sublimating now).  On the other hand, in wet ice, especially when it's cold out (i.e. the screw is colder than the ice), they can be really sticky and hard to drill with... which is why I am not using those on hard leads, but reserve them for anchors.

My conclusion so far: aluminum screws are great in cold dry ice, and generally suck in wet ice.  But none of this matters much if you use them for your belay anchors only and like the weight saving.
zoso · · Unknown Hometown · Joined Jun 2007 · Points: 495
rocknice2 wrote: http://mra.org/wp-content/uploads/2016/05/Beverly_IceScrews_Final.pdf

https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-622-experimental-projects-ii-fall-2003/projects/alziati_bennett.pdf

Thx for those links but none of the 3 cited study either of my points (1.  thread style or 2.  threads for the full length of the screw).

These 2 points seem pretty important IF a downward placement angle is, in fact, strongest.  

Some interesting points I noted below.  Notice how many only add to the confusion on the subject.


"This graph does not show the trends observed in the Harmston & Luebben study. Instead, it does not show any trend; rather it confirms that the optimum placement angle for screw placement is at zero degrees, i.e. perpendicular to the wall.
The thousands of tiny bubbles within the ice act as a honeycomb structure. It is thought that the air pockets provide crumple zones and thus allow it to absorb more energy.
One further explanation is that the bubbles act as crack blunters and prevent the crack from propagating.

It is clear that, in almost all cases, the zero degree placement angle gives the highest pullout load. Also observable is that, for a low load rate case a negative angle is preferable to a positive angle, whereas for a high load rate case the positive angle holds more than the negative one. In the lower loading rate case the negative screw placement angle puts the load path in line with the pulling force from the MTS machine, thus allowing the screw threads to hold the load. In the higher loading rate case the positive angle of screw placement allows the ice screw to hold a higher load because the ice screw must then shear through ‘extra’ ice before it can be pulled out. The nature of the high rate pull out is that stress concentrations build up and break the ice in a brittle fashion, the positive screw placement angle puts more ice in the path of the failure crack than the negative angle.

Another finding, and possibly the most valuable to the climbing community, is the much greater dependency of loading rate on failure load rather than screw placement angle or ice type. This is significant to climbers as they have some control over the loading rate on an ice screw. Using a combination of ropes that can stretch more and friction devices in the belay system, the loading rate on an ice screw can be reduced significantly. This project has shown that a decrease in loading rate of a factor of 100 gives an increase in the supportable load of a factor of three.

The results of our tests were surprising. At first glance it appears that there is no significant difference in impact force between passing and failing screws, and that it looks like a 50/50 shot at failing a screw. Both categories of pass/fail fall into the same relative bins.

What was observed is that the stubby screws saw high impact forces of nearly 15kN without failure. This fact only supports the reasoning that ice placement selection ability becomes the important factor.

Higher impact forces above 10 kN are more than likely to cause ice screw failures. At this load, a narrow margin appears to exist between passing and failing. High impact forces can be created by simply overdriving a system with a large mass and can lead to anchor point failure (no heavy ice lead climbers allowed). There are other ways at achieving this same end result such as, using an old rope, clipping two double ropes together when only one should have been, or increasing friction in the system by any modality are several of those ways.

Short (“stubbie”) screws when placed in good ice provide a significant amount of protection that was quite unexpected and equivalent to that of rock gear when placed at ≥+10o but ≤+30o. By showing this, we have validated the concept of what angle ice screws should be placed in vertical waterfall ice as previously studied by Luebben and Harmston. While poor screw placement is always a possibility, poor ice screw placement is as weak as “rattly” rock gear. The analogy can be made that poor ice screw placement is similar to just throwing your rock climbing rack on top of the rock, clipping your rope to it and jumping off the cliff, only to hope that the gear somehow miraculously catches on something and holds your fall. Proper protection placement is crucial.

Ice gear is good if placed in zones of compression or areas devoid of large air pockets within 15-30 cm of the screw placement. Anecdotally, small air bubbles within the ice do not seem to matter on vertical waterfall ice.

During the course of our ice screw testing, we were able to test three ice hooks, all three failed, did not slow the test mass down at all, and became a sharp flying projectile heading towards the test mass (climber)."


So...take home lesson:  "It depends".


Colin O'Brien · · Bozeman, MT · Joined Jun 2012 · Points: 140

seems to me like the take home lesson is actually that ice screws can be incredibly effective, but depend entirely on careful evaluating the quality of the ice.  Will Gadd has said similar things - far better to spend the time and energy hacking a good placement for a shorter than to assume a longer screw is good. Evaluating ice quality isn’t science, which might yield the “it depends” answer, but one can certainly develop an eye for good ice and take some comfort in knowing that a well-placed screw is bomber.  

Similarly, ice hooks (specters?) are just as sketchy as they seem.  Not worth placing?

zoso · · Unknown Hometown · Joined Jun 2007 · Points: 495

Agreed it's comforting that even a stubby is pretty bomber in good ice.   I've never given screws that much faith.  

Now we should all start taking whippers.  

You first.  

Marc-Olivier Chabot · · Gatineau, QC · Joined Sep 2016 · Points: 440

I fell on a 10cm screw and it held perfectly. The ice was very good.

Bill Kirby · · San Francisco CA · Joined Jul 2012 · Points: 480
Colin O'Brien wrote: 
Similarly, ice hooks (specters?) are just as sketchy as they seem.  Not worth placing?

 Spectres are for frozen moss

Colin O'Brien · · Bozeman, MT · Joined Jun 2012 · Points: 140

Right, Bill.  But the article called them "ice hooks," and said they are basically garbage for protection but become flying daggers aimed at your face. That was a big takeaway!

Guideline #1: Don't be a jerk.

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