Uber thin static cord for occasional long rappel

Thinking of buying a super thin, super-static line that could be stashed in a pack for emergencies or the occasional rappel on ultra-lightweight alpine missions.
https://www.amazon.com/gp/product/B004L234TW/ref=ox_sc_act_title_1?smid=A3JHUUPV3ODEZ3&psc=1 
Essentially I'd be rapping off a single dynamic rope, blocked at the anchor, and tie a super thin pull cord to the end.

Lots of cons, I know.
- Biner block can get stuck
- If ropes get stuck I can't climb/rap on the pull cord
- Probably hard to pull on such a thin line (although being static should help)

- What kind of knot would you use to tie the pull cord off to the end of the rap line?

This would be more of a.. I want to solo this classic alpine route rather quickly but it requires one 100 ft rappel to get down, so it'd be nice to pair my 8mm 30m with 100 ft of 3mm pull cord.
Sure I could get some legit 6mm supercord but I'm too cheap.

Cheers!

The responses in this thread apply to your question:

https://www.mountainproject.com/forum/topic/114980508/2mm-pull-line-for-full-rope-length-rappels#ForumMessage-114980558

Tyler S wrote: Thinking of buying a super thin, super-static line that could be stashed in a pack for emergencies or the occasional rappel on ultra-lightweight alpine missions.
https://www.amazon.com/gp/product/B004L234TW/ref=ox_sc_act_title_1?smid=A3JHUUPV3ODEZ3&psc=1 
Essentially I'd be rapping off a single dynamic rope, blocked at the anchor, and tie a super thin pull cord to the end.

Lots of cons, I know.
- Biner block can get stuck
- If ropes get stuck I can't climb/rap on the pull cord
- Probably hard to pull on such a thin line (although being static should help)

- What kind of knot would you use to tie the pull cord off to the end of the rap line?

This would be more of a.. I want to solo this classic alpine route rather quickly but it requires one 100 ft rappel to get down, so it'd be nice to pair my 8mm 30m with 100 ft of 3mm pull cord.
Sure I could get some legit 6mm supercord but I'm too cheap.

Cheers!

I tried 4mm pull cord.  It is too small - impossible to pull down.  Suck it up and stick with 6.

One issue with spectra is it has a very low melting point which can make rappelling on it possibly sketchy. Technora has a higher melting point.

Cool cool. Sounds not worth the effort/issues. Thanks y'all

Here's what the Canyoneers are using.  It's still pricey and probably only a viable option if weight is the primary consideration.

Ultra Thin Pull Cord

That canyoneering cord looks interesting for what they describe as "close-to-ideal situations," but I'm curious how one even joins a cord that thin to a regular rope? 

I use a 6mm Edelrid Kevlar tag line for alpine traverses and wouldn't go with anything thinner esp on hanging rappels.  Adding that the thinner you go the more time you'll spend untangling the rope after a pull.

John Bjerregaard wrote: Here's what the Canyoneers are using.  It's still pricey and probably only a viable option if weight is the primary consideration.

Ultra Thin Pull Cord

From the description, it sounds like canyoneers mainly use it as a fiddle stick pull cord (Fiddle Stick), not to pull the rope through the anchor.   

 And it even says in the description that it is to be used in "close-to-ideal" situations, and on "special occasions" (a special occasion for a canyoneer is some seriously crazy shit me thinks).

Edit : For those that don't know...  Once the fiddle stick is pulled out of the knot, the whole knot comes undone, and the rope can be pulled free of whatever it is wrapped around.  Since you don't have to pull the entire length of the rope through a carbiner there is far less risk of getting the rope or pull cord stuck

cyclestupor wrote:

From the description, it sounds like canyoneers mainly use it as a fiddle stick pull cord (Fiddle Stick), not to pull the rope through the anchor.  And it even says in the description that it is to be used in "close-to-ideal" situations, and on "special occasions" (a special occasion for a canyoneer is some seriously crazy shit me thinks).

Makes sense. I guess for that purpose you don't need to join the ropes so my question above is moot.

Ronald B wrote:

Makes sense. I guess for that purpose you don't need to join the ropes so my question above is moot.

You don’t have to join them in a biner block set-up either, which is what I think OP is up to. This also confused people in the previously cited thread: OP is doing a single rope rap, with a pull cord, and is not rapping on the thin cord, just using it as a pull cord.

Andrew Rational wrote:

You don’t have to join them in a biner block set-up either, which is what I think OP is up to. 

Oh interesting, I've only ever seen the following two biner block setups in the wild, both of which involve joining the ropes:

and


What is the method where you don't have to join the ropes?

Thanks, missed the biner block part.

Consider this- https://sterlingrope.com/store/climb/cordage/high-tenacity-cords/5-4mm-v-tx-cord-2
Bummer it's only sold in big spools, but it looks like a great option as the lightest in the skinny rap line category
Edit: tough to beat the price on the Amazon dental floss though!   

Ronald B wrote:

Oh interesting, I've only ever seen the following two biner block setups in the wild, both of which involve joining the ropes:

and

What is the method where you don't have to join the ropes?

With whatever gear I easily had at hand, this. Rap the fat rope only. Pull the skinny. Use a fatter knot, and a smaller biner, than what I show, to make sure the knot can’t pull through or jam in the biner. 

Andrew Rational wrote:

With whatever gear I easily had at hand, this. Rap the fat rope only. Pull the skinny. Use a fatter knot, and a smaller biner, than what I show, to make sure the knot can’t pull through or jam in the biner. 

Sweet, thanks for going through the trouble of actually rigging an example of photographing it! 

Andrew Rational wrote:

With whatever gear I easily had at hand, this. Rap the fat rope only. Pull the skinny. Use a fatter knot, and a smaller biner, than what I show, to make sure the knot can’t pull through or jam in the biner. 

That sure looks like a biner block to me.

Gunkiemike wrote:

That sure looks like a biner block to me.

Textbook, almost, agreed. I was just clarifying for Ronald how a biner block could be set up without actually joining the (wildly differing diameter) ropes.