When to use which length quickdraw?

I have 18 quickdraws. 15 of them are 11cm dogbones and 3 are 18cm. Suppose Im headed to a route with 11 bolts. I imagine I would bring 12 of my 11cm quickdraws and two of the 18cm. 

Pretend the route wanders around a bit. first five bolts straight up, the next two are up and to the right, then the remaining bolts straight up again. Where would be the most optimal place to use the 18cm draws to reduce drag? 

I suspect it doesn't really matter...

Take all 3, extend the 5 straight up ones and the next two. It definitely matters. Remember, you're trying to make the rope go in as straight a line as possible. 

I thought that the answer to your hypothetical would be obvious, but for reasonable bolt placements it's actually not. In most scenarios you would get the least rope drag from extending 7th and 8th bolt. The "obvious" answer of extending the 6th and 7th is almost as good though.

Changes in direction create more drag higher on the route since there is more rope weight. So all else equal you should prioritize extension later in the pitch over earlier in the pitch. This is the reverse of most people's intuition.

Somebody built a fun rope drag simulator you can play around with:
https://github.com/kylemathenia/Rock-Climbing-Rope-Drag-Simulator

Austin Donisan wrote:

I thought that the answer to your hypothetical would be obvious, but for reasonable bolt placements it's actually not. In most scenarios you would get the least rope drag from extending 7th and 8th bolt. The "obvious" answer of extending the 6th and 7th is almost as good though.

Changes in direction create more drag higher on the route since there is more rope weight. So all else equal you should prioritize extension later in the pitch over earlier in the pitch. This is the reverse of most people's intuition.

Somebody built a fun rope drag simulator you can play around with:
https://github.com/kylemathenia/Rock-Climbing-Rope-Drag-Simulator

Except that you have to climb/deal with drag created at the start of a pitch much longer than drag created near the end

Blake M wrote:

Except that you have to climb/deal with drag created at the start of a pitch much longer than drag created near the end

not when "the first five bolts are straight up" according to the scenario we were presented by the OP. Not sure how you create drag in that scenario, though I'm open to being enlightened.

Depends on that the OP means when he talks about this layout I imagined something like number 1 but number 2 is also possible. 

X.                                               X. 

X.                                               X. 

X. E                                           X. E

                 X. E                          X. E

            X.                           X. E

X.   E                        X. 

X.                             X. 

X.                             X. 

X.                             X. 

X.                             X. 

1.                              2

X=bolt

E= Extension 

In general, I'd recommend taking all your long draws and then filling in however many more draws you need with your shorter draws, at least when we're talking about only having a few longer draws. The long ones work just as well wherever the short ones work so if the route doesn't wander, it's not a big deal to have a longer draw. Plus, if there's a bolt where your shorter draw puts the rope running over a sharp edge or the short draw puts the biner right on an edge the long one may avoid that.

Regarding the drag, it will certainly make a difference. In Seb's diagram above, you can see the priority of extending where the direction changes and where it returns to the original bolt line/transitions to a new bolt line. That's pretty much what you're going for. Not sure how the first five could be extended with only 2 or 3 longer draws, but if it was really bad you could double up some of your 11cm draws to do that.

Not a bad idea to have 2-3 alpine draws in your quiver for such situations.  

                          X

                          X. E

                          X. E

                          X. A

                  X. 

         X. A

         X. E

         X

         X

         X

Depending on the specific draws you have, I’m sure a couple Petzl Ange S alpine draws would be both lighter and reduce drag significantly more allowing you a better shot to send.

Because I can’t climb harder, I try to climb smarter

(Some love em, some hate em, but for what it’s worth, almost all my draws are Ange S.  They seem to be secretly helium filled.  But then I’m not yarding on them or projecting either).

Edit: sequence corrected per Christian below

not to nitpick too much but in the above situation but I believe the correct order is to move bolts 5 & 6 down to 4 & 5, and replace that first alpine with a simple qd in between the two alpines.

Christian Hesch wrote:

not to nitpick too much but in the above situation but I believe the correct order is to move bolts 5 & 6 down to 4 & 5, and replace that first alpine with a simple qd in between the two alpines.

You’re right.   I should’ve thought thru the placement order better.   It would be a total waste of an alpine draw where I put it.   I corrected it. 

Took me a few years to have it figured out, def takes mileage and lots of reps, but sure is nice when you get it right and drag is nonexistent :)

Blake M wrote:

Except that you have to climb/deal with drag created at the start of a pitch much longer than drag created near the end

WARNING: geek level nitpicking ahead

This simple OP question is definitely more subtle than it would seem at first.  

I think some are underestimating the importance of this consideration presented by Blake.  

The info/ suggestions presented by Austin, and Seb may be misleading to a degree, or could be misapplied if trying to optimize for your climb.  

There is no question that if computing just the friction drag affects, they are worse and more pronounced the higher up the climb compared to lower on the climb.   That said, this doesn’t tell the full story or its meaning to you the climber.   

For simple discussion’s sake, let’s assume Seb’s bolt scenario number 2.  Shown below.  If we simply measure the drag when at the chains, the high drag ones are at the top.   But if the crux was below bolt 9, you’d be better off clipping your 3 longer draws at Ex, E, E (bolts 4,5,7) rather than E, E, Ey (bolts 5,7,8).   Bolt 6 doesn’t need extension in either scenario.

Basically in terms of ENERGY expended by the climber (work done) extending higher or lower is essentially a wash at the end….due to the drag magnitude as well as total energy expended both being proportional to the height climbed — In short, you have higher drag up top but climb less distance with it, lower drag down low, but climbed longer distance with it.   Pick the extension that minimizes the drag before the crux section 

                   X.               

                   X. 

                   X. Ey

                   X. E

           X.  

X. E

X. Ex                       

X.                             

X. 

X. 

X=bolt

E= Extension 

Disclaimer:  wasn’t able to download the exe file for the drag simulator on my phone, And I just very quickly did work/energy calcs in my head for high and low scenarios like example, so feel free to run the analysis deeper and correct me.  

Keep in mind that your belayer isn't holding the rope banjo tight, but rather making a slight dish shape, so as to mitigate that drag on the initial bolt, which I assume to be the largest part of why initial bolt/gear drag isn't as large a consideration as higher up (complete conjecture on my part, though slightly educated conjecture)

My solution would be to exchange a couple draws for 2' slings before I started.  Look  at the route - imagine the straightest line you can (and consider the in and out (roofs/edges) of the climb as well) - then choose the draws/slings combination that would best make that happen.  There may be times that 24" and 48" even would make the best choice.  Buying a few more runners would be a good idea maybe?

The main reason the drag increases the higher you go up a climb is that the tension in the rope is increasing due to weight of the rope as it goes up (more rope weight out) plus the accumulated drag “pulling” from below.  This tension (and it’s angles) is what puts the Normal force component on the biner to create the drag/friction force.

It’ll always be larger in magnitude the higher you go (for any given angle)

But the work a climber does is always increasing the higher he/she goes.  Whether you drag 5 lbs up for 2 feet, or 10 pounds up 1 foot, you spend the same amount of energy, so that’s why it sorta can even out in the wash in terms of overall effort.

For climbers, though, they probably want to minimize effort around the crux, rather than the easier parts.