MicroTrax Keeper/TR solo cord

OK, kiddos. It’s time for another “show ’n tell”. This time something I ripped off the basic idea from a Mt. Proj. post. <https://www.mountainproject.com/forum/topic/119480325/didja-know-the-petzl-micro-traxion-has-a-keeper-cord-hole> The poster claims that someone associated with Petzl told him about this hidden secret. 

There’s a small hole in the plastic casing of the MT that goes through the spine and out the side. This allow a 1.5 mm cord to be attached that can act as a keeper cord or attachment point for TRS necklace/webbing/harness

 

• If you take the MT off before you rap, it helps keep you from dropping it
• If using the MT as primary device, it can be used to connect to your necklace/webbing/harness and will hold it up for feeding
• It’s simple to take ‘biner out, remove MT from rope and let it dangle from necklace while rapping. 
• Or, you can take ‘biner out, lockout the MT and rap. This leaves on the rope and ready to reconnect at the base. It seems to hold it at an angle where it won’t catch the cam and re-engage. A nasty habit that it normally has. 

The neat thing about attaching a cord this way is that doesn’t interfere with the opening and closing of the side plate

Only 1.5mm cord or less will work. (You might be able to get a 2mm piece through but it would be a challenge)

1. cut a length of cord (better too long than short 10” is a good length
2. melt one end and with a its grab the end and pull and twist. This gives a nice taper to the end.
3. tie a loop using an overhand knot in the other end making the loop the desire size.
4. take the other end and thread it through the MT casing from the spine side gently feeding it until it comes out the side of the casing.
5. tie an overhand stopper knot adjusting it for the desired length
6. cut the extra cord about 1/2” from the knot
7. burn the end so that a little molten blob forms near the knot
8. pull loop end until the knot completely seats in the the hollow space in the MT casing.

(If I were just going to use as a keeper cord I’d make it a bit longer and use the loop to form a slip knot that could be cinched down on the ‘biner)

Wah-La!

PS apparently the Petzl Sm’D ‘biner has a matching hole if your primary goal was to have it on a “leash”. If you used this ‘biner, you'd do away with the loop and just have another stopper knot on each end of the cord.

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MicroTrax Addendum

(only pertinent if you use the MT for TR-soloing and hold it up by a leash connected to the MT as detailed above

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The issue:

If you use the MT as your primary device held vertically with the leash as detailed in my previous post, it’s possible that it can induce more drag than if it is held vertically by making the connection to the ‘biner. Whether or not you’re paying a friction penalty and whether it’s significant or not depends upon the ‘biner/rope combo used. 

Should you give a shit? Well like most things, it depends...

Simple experiment:

You can perform a simple test to see if you’re paying a friction penalty by using a leash to connect the MT to your necklace/webbing/chest harness. In general, the larger diameter the rope and the larger the diameter/cross-section of a biner, the more likely there could be a significant amount of friction versus a simple doubled loop around the ‘biner connected to the necklace/webbing/harness.

Do this:

• Hang the rope you use and put the MT with leash on it and pull up the rope - note the amount of friction
• Do same thing but instead of using the leash, use a loop of cord doubled around the ‘biner and pull up the rope - note the amount of friction

If you don’t notice any difference or if the difference is insignificant to you, then you’re golden - forget about the rest of the post. If you do notice that there’s significantly more friction/drag using the leash, there’s four possible solutions:

1. Use a smaller rope size if you’re using 10 or larger.
2. Use an I-beam cross-section or smaller cross-section ‘biner if you’re using a large round cross-section ‘biner. In testing, I used a Edelrid HMS Strike Slider with a 9.5 rope, and while I could sense there was a bit more drag, it was not objectionable.
3. Forget the MT leash and just use the doubled loop of cord around the ‘biner and put up with the hassle of putting it on and off and hope you don’t drop it.
4. Forget the MT altogether and use a Roll’nLock which you don’t have keep putting on and off when rapping because it positively locks-out (and it feeds just as well) :-)

Technical explanation:

• The reason that the MT leash may have more friction is that the MT is pulled (held up) which forces the ‘biner down against the rope and pulley. (photo 1). With the wrong rope and ‘biner this causes noticeable friction
  
  

• With the ‘biner cord loop connection, the ‘biner is lifted up and pulled away from the rope/pulley which reduces the pressure on the rope. (photo2) 
  
  

Bottom line:

We’re not talking about great amounts of friction here in most cases. However, it may be enough to cause you to re-evalutate whether to use the MT leash connection or not, and if you do whether to try and mitigate that. For me the whole leash thing came up because I was constantly taking the MT on and off to rap because of the unpredictable lock-out feature. It’s unfortunate that Petzl didn’t do a better job engineering that because it’s neat feature that's easy to operate with one hand. BUT, if it's going to lock or unlock unpredictably on me then it’s not something I want to use.

OK, there you go. Probably more info than most people ever wanted or need to know. TRSers can now have their own leash vs no-leash “discussions" just like surfers and ice climbers! :-)