Soft vs. Rigid Stems/Thumb Loops, does it even matter? (Highlining)

Hey MP,

I'll preface this by saying, I don't climb much. Rather, I highline (slacklining) and have been heavily relying on trad anchors recently.

I've placed all sorts of passive pieces without fear: hexes, nuts, tricams. The constant load of a highline anchor (about 2-3kN at the masterpoint) doesn't scare me here since the wires/dyneema slings don't necessarily deform. (The masterpoint will nominally see 5kN to upwards of 10kN if rigged poorly).

This is where cams have caused problems for me. The thumb loop of a BD C4 for instance, is made of a plastic covered wire that would almost certainly deform if under constant tension. Same can be said for PowerCams, Aliens, Friends, and Totems. I own C4's and I have avoided using them for this reason.

That being said, MasterCams and Dragon cams have stem-sling interfaces that appear to more aptly handle constant-tension scenarios.

MP, does this shit even matter? Is it just an aesthetic thing or will I be weakening the cams over time? Should I trade all my soft-stem cams for Masters and Dragons?
Roast me.

Brandon A Peterson wrote: Hey MP,
...
Roast me.

How are you not bored of slacklining yet?

(Also a highliner and climber here) Considering that that 2-3kn load is going to be shared with anywhere from 4-9 pieces, I’m not generally worried about cyclic load deformation and I just clip the climbing biners already on my cams for equalizing the anchor. If each cam is only going to see ~<1kn (sometimes more because it’s never truly equalized), I feel pretty good about using aluminum in this case. Opposite/opposed non-lockers on each piece if you’re really worried about it. 

I dont like using my climbing cams for natural highlines because of the wear it puts on them. I have an assortment of rigid stem friends and hexes that I use for highline anchors and I keep quicklinks on them instead of wire gates. I guess if you only use your cams for highline anchors, you dont need to worry about that specific wear that whipping/tension on highlines inflict.

Brandon R wrote:

How are you not bored of slacklining yet?

Slacklining is boring. 

Only way it's fun for me now is if I have to hike a rig far/high into the alpine. 

So no surprise, I'm starting to climb more.

Christian Black wrote: (Also a highliner and climber here) Considering that that 2-3kn load is going to be shared with anywhere from 4-9 pieces, I’m not generally worried about cyclic load deformation and I just clip the climbing biners already on my cams for equalizing the anchor. If each cam is only going to see ~<1kn (sometimes more because it’s never truly equalized), I feel pretty good about using aluminum in this case. Opposite/opposed non-lockers on each piece if you’re really worried about it. 

Not worried about using alu vs steel, though I have more quicklinks than crabs so I just happen to use them. 

My question really drives at the fact that cams, from the lobes to the sling, are usually made of flexible wire covered in plastic. They are designed to see a DYNAMIC peak load from 2-10kN, rather instantaneously. (Even then, I've seen some F'ed up cams from whippers). I'm apprehensive of using relatively flexible stems for the sake that the cam's shape will change over time, possibly cracking plastic, exposing wire for possible oxidation, etc. especially where the sling and thumb loop interface.

What do your cams look like? Did any part deform/crack or are you sitting pretty like-new?

People hang portaledges from cams all the time. For extended periods. Ask them. 

Brandon Peterson wrote:

Not worried about using alu vs steel, though I have more quicklinks than crabs so I just happen to use them. 

My question really drives at the fact that cams, from the lobes to the sling, are usually made of flexible wire covered in plastic. They are designed to see a DYNAMIC peak load from 2-10kN, rather instantaneously. (Even then, I've seen some F'ed up cams from whippers). I'm apprehensive of using relatively flexible stems for the sake that the cam's shape will change over time, possibly cracking plastic, exposing wire for possible oxidation, etc. especially where the sling and thumb loop interface.

What do your cams look like? Did any part deform/crack or are you sitting pretty like-new?

It doesn’t matter whether the load is dynamic or static. Hanging from an anchor is a static load, a top rope is a static load, and we still use cams for some anchors in technical rescues designed to raise and lower a 2kn load, similar to highline tension. It might link your cable if you use quick links straight through the loop, but the seem webbing is wide enough such that it won’t kink, you really just want as wide of a surface area as possible on that loop, that’ll make the difference between kinking or not.