Breakaway tether-ice tool connections

I am looking for advice on creating breakaway tether connections to my ice tools, for mixed climbing.I like to attach tethers to my tools on committing multi-pitch mixed climbs, where I do not want to drop a tool.  I also want to avoid breaking the pommel (Petzl Ergonomic) or having sharp pointy things slingshot towards me, during an unexpected tether fall.  

Source: https://www.thealpinestart.com/2019/01/22/tech-tip-impact-forces-during-a-fall/ 


Source: https://www.blackdiamondequipment.com/en_US/qc-lab-how-strong-is-the-spinner-leash/qc-lab-how-strong-is-the-spinner-leash.html 

Ideally, it should be something low profile that doesn't interfere with gripping or swinging the tool.  Photo below of what appears to be a low-profile connection, with minimal interference.  
Source: https://www.tomlivingstone.com/climbing-blog-1/2018/3/22/petzl-ergonomic-review 

Are there any particular combinations of cord and knots that are strong enough to hold a dropped tool, but will reliably break during a tether fall (at lower loads than the Nomic/Ergonomic pommel)?  

Note: I use both the black diamond spinner leash and blue ice boa leash, for tethers.  

Your best bet is probably high strength velcro. Just experiment to find the size needed.

On second thought, might not be as functional in ice climbing temps.

t.farrell wrote: You could probably make something out of shock cord and a cord lock. Especially with the real skinny stuff, it would probably hold the tool if it fell but release under body weight. 

This is what Ive done ^ ... Just use skinny shock cord. No way that shit will hold your weight but would for sure hold the tool. 

You can use zip ties and vary either the size of the zip tie or the number of zip ties to get the breaking force you want.  

You might also look at the magnets that are used on things like fly fishing nets. They break away with a tug when you need to reach with your net, but otherwise keep the net close by your side. 

Zac St. Jules wrote:

This is what Ive done ^ ... Just use skinny shock cord. No way that shit will hold your weight but would for sure hold the tool. 

+2 on the skinny shock cord. Tie a small loop. It will break under body weight.

Skiers who use leashes instead of brakes face the same problem. Leashes can have some advantages over brakes, but you don't want to be dragged into an avalanche by skis that won't fully release either. Hence you have breakaway ski leashes that are meant to snap under sufficient weight in the event of an avalanche. Here's an example:

https://skimo.co/bnd-ski-leashes

The leash itself is not likely what you want, but you may be able to take the fuse link (the plastic G shaped thing) from the leash kit and integrate that into your ice axe leash system.

I've tried the zip tie trick mentioned by Jason4Too above for my skis but I've found that the specs advertised for zip tie breaking strength are often highly inaccurate, especially in the cold, and I've had them break on me for seemingly no reason at all. I've heard that there is variability in zip tie quality by brand/source, so it's possible you could get higher end zip ties that would be more reliable, but the fuse links are actually made for your kind of use case and are probably more trustworthy.

Also, surprising number of familiar faces here...

Zac St. Jules wrote:

This is what Ive done ^ ... Just use skinny shock cord. No way that shit will hold your weight but would for sure hold the tool. 

Dont listen to this guy he's a punter 

I tried out shock cord, but found it to be a bit too bulky.

The most promising breakaway connection that I have found thus far is 1/4” flat nylon shoe lace.  

https://www.mec.ca/en/product/5044-211/1-4%22-%285mm%29-Nylon-Flat-Shoe-Lace

I have not done any drop testing to determine the breaking strength.  If there is anyone located near Boulder, CO with a load cell and a desire to test these breakaway connections, please send me a PM.

I think your best bet would be using B&D ski leashes. You can get a 40# or 60# fuse. Maybe extend them with some cord if too short. You could mess around with using more or less coils with more or less cord.
Though I'd probably want to test that it could actually hold the tool if dropped the full length of whatever leash configuration you end up with.

http://www.bndskigear.com/skileash.html