Placing Cams in Poured Concrete?

Jeffrey K wrote: The responses as to why the placement is bad aren't very clear, so here goes.

You should be clipping a quickdraw, or really an alpine draw, to the cam and clipping into that. Don't clip directly to a biner connected to the cam. Basically you're pretending your cam is a bolt; treat it as you would a bolt.

On routes where rope drag is potentially an issue by just doing that, you'd always use an alpine draw and extend it. A straight crack like this does not require an extended draw but still requires a draw, not a straight clip to the cam.

A straight upward crack shouldn't automatically require extension, especially in your first few pieces. Dynamic ropes stretch further than you'd expect, and hitting the ground is easier than you'd wish. Take a clinic with a professional guide and you learn when, where, and why any type of extension is required. I've learned that climbers are often prone to extend anything and everything without really knowing why they're doing it. 

Extension should be considered in cases of walking and minimizing rope drag. We can't know why this piece walked without seeing and feeling the inside of that crack, could be very polished and super parallel. 

Jeff. Put down the shovel.

Jeffrey K wrote:

Yes, the OP should always use a draw on cams until he has the experience to know when he doesn't have to. 

Why are people putting cams in the wall 5 feet off the ground? How would the extra 12 or 18cm cause a problem? If you're doing something that's getting you within 12 to 18 cm of decking YGD soon anyway.

I get it. It's faster & easier to clip the biner on the cam. I can be lazy, too. But it's simply not safer and not good practice as someone just starting Trad leading.

You guys would probably show up at a driving class for teenagers and tell them "Um, driving 20 MPH over the speed limit is fine and turn signals are always optional!" Technically pretty true, and it'll save you some time, but contextually idiotic.

I remember when first started to trad climb too.  

Jeffrey K wrote:

Yes, the OP should always use a draw on cams until he has the experience to know when he doesn't have to. 

Why are people putting cams in the wall 5 feet off the ground? How would the extra 12 or 18cm cause a problem? If you're doing something that's getting you within 12 to 18 cm of decking YGD soon anyway.

I get it. It's faster & easier to clip the biner on the cam. I can be lazy, too. But it's simply not safer and not good practice as someone just starting Trad leading.

You guys would probably show up at a driving class for teenagers and tell them "Um, driving 20 MPH over the speed limit is fine and turn signals are always optional!" Technically pretty true, and it'll save you some time, but contextually idiotic.

You are the worst kind of person.

Michael S wrote:

I'm thinking because it's just too parallel... If there were some inconsistencies for the cam lobes to grab it would help keep from rotating. Or if it had a rougher texture. I bounced on them pretty good and they seemed to "set" solid under a load.... But I'm newer to placing cams as well, so what do I know.

I didn't know until I whipped! It was unexpected, and it was big! And it was a load of dopamine to the dome! It was AWESOME!

Eric Roe wrote:

I clip straight into the racking biner on vertical splitters all the time, haven't died yet

Same.

The numbers 5000-6000 psi make me think a fall would at least damage the concrete.  Say a small fall places 3kN (~700lbs) on the top piece.  The 15-degree camming angle quadruples that, but each lobe sees 1/4 of the load so again 700lbs.  700 / 6000 ~= 1/8 sq inch.  A lobe is 1/4" wide, so its contact would have to be 1/2" long to make 1/8 sq inch.  The concrete would have to be crushed noticeably to form a 1/2" long contact groove.

Or does 5000-6000 psi include a 5x safety margin (meaning it can actually hold 25000-30000 psi) ?

Clipping the cam directly probably won't get you killed directly but it will....

- Make your cams more likely to rotate into a bad placement that could blow in a fall. A "reverse zipper" will get your attention.

- Make your cams more likely to rotate into a bad placement and get stuck.

- Cause you major rope drag that could lead to a fall.

Pros don't extend because they are trying to save energy on the hard stuff. You mere mortals.need to extend.

Serge Smirnov wrote: Or does 5000-6000 psi include a 5x safety margin (meaning it can actually hold 25000-30000 psi) ?

There is a safety factor but it is nowhere near 5x - more like 10 or 20%.  There is also a wide range in concrete strengths - could be anywhere between 3,000 psi and 8,000+ depending on application.

What is getting lost in all the back and forth on extension is that the point is moot if the placement in question is garbage to begin with.  Concrete can have a wide range of finishes, from fairly rough to highly polished.  More often than not the finish is pretty smooth if there is no sandblasting, acid washing, etc after removing the forms.  My guess is that some concrete behaves more like polished limestone than any other type of rock, which means it might hold, but there is a relatively high chance it will not due to the low friction coefficient.  In the buildering video that one guy takes a whip and you see a hint of dust coming out that to me looks consistent with a piece ripping - but then the video cuts out which is pretty annoying.

So it might work but it might not, and it would be highly dependent on the nature of the concrete.  I wouldn't whip on it!

Travis S wrote:

You are the worst kind of person.

Technically pretty true, but contextually idiotic.

Tradiban wrote: 
Pros don't extend because they are trying to save energy on the hard stuff. You mere mortals.need to extend.

Gear doesn't need to hold on hard routes? Pros would have the gear extended on their rack prior to those those photo shoot routes if they believed it was necessary.

Extension is generally not needed on straight, short routes on most types of rock. The smooth concrete is an example of the exception, not the rule.

I don't know about structural bridge codes in Tx, but in Pa the sub structure of bridges typically is 3000psi concrete (seen in the picture), usually the fancy 4000psi+ is in the deck/superstructure. Bridges of that scale typically don't have facades, it would be a waste of material and taxpayer money, so i would suspect that the expansion joint that he's plugged cams into is the same as the concrete for the entire abutment, around 3000psi concrete.

From ( web.mit.edu/custer/www/rock… ) hanging on a cam you can expect 1500N (335lbs) outward force across 4 lobes or a mega fall around 12,000N (2698lbs) across 4 lobes. Say each lobe has a contact area of 0.25in x 0.25in = 0.063in^2 ...so the outward pressure on the concrete is 335lb/4lobes/0.063in2 = 1340psi < 3000psi concrete (resting) or 2698lb/4lobe/0.063in2 = 10796.4psi >> 3000psi concrete.

So basically, if my math/estimations are any bit close, resting on a cam will likely scratch the concrete and piss off the owners, taking a hard fall will damage it and really piss off the owners. Don't fall or get caught...

Disclaimer: No idea if my application of Max and Min cam lobe forces is accurate so i only did a very quick google search, just some quick napkin math...

Sloppy Second wrote:

Gear doesn't need to hold on hard routes? Pros would have the gear extended on their rack prior to those those photo shoot routes if they believed it was necessary.

Extension is generally not needed on straight, short routes on most types of rock. The smooth concrete is an example of the exception, not the rule.

I agree, a straight route doesn't "need" extensions but typically for the rest of us extending is a good idea for my above stated reasons.

Since you're toproping, but mock-placing cams, I wouldn't worry about dying.

MisterCattell Cattell wrote: Since you're toproping, but mock-placing cams, I wouldn't worry about dying.

But I wana whip!!  LOL yeah I'm not worried. TY! Also may try aiding with the cams and leaving a little slack in the top rope. That'll tell me something.

Tradiban wrote: Clipping the cam directly probably won't get you killed directly but it will....

- Make your cams more likely to rotate into a bad placement that could blow in a fall. A "reverse zipper" will get your attention.

- Make your cams more likely to rotate into a bad placement and get stuck.

- Cause you major rope drag that could lead to a fall.

Pros don't extend because they are trying to save energy on the hard stuff. You mere mortals.need to extend.

­^^^ This.

Also those pros may have been rehersing the route dozens of times. They would know pretty well what's likely to rotate and what's not. If it's your first time/few times on a route you likely don't. Odds are they also are way less clumsy in how they move pass their gear, therefore way less likely to make rushed moves that would help stuff rotate....

Anonymous wrote:

Bridges are cool and all but, are there really no rocks in TX?

There are but the closest (Mineral Wells) is almost 2 hours away, sucks crowded with Boy Scouts and not worth the trip. Wichita area Ok. and Enchanted Rock are nice but about 4 hours away. Hauco Tanks is a 9 hour drive. Yes I do go climb outdoors, but I'm a little of a modern dirtbag and don't have money to traval all the time to go climb. I go when I can, a few time a year maybe. So, for now I'm forced to spend my time at the gym(yawn) and find things like the bridge. Climb what you can as long as your climbing...Right?  Lolz

Tradiban wrote: Clipping the cam directly probably won't get you killed directly but it will....

- Make your cams more likely to rotate into a bad placement that could blow in a fall. A "reverse zipper" will get your attention.

- Make your cams more likely to rotate into a bad placement and get stuck.

- Cause you major rope drag that could lead to a fall.

Pros don't extend because they are trying to save energy on the hard stuff. You mere mortals.need to extend.

Franck Vee wrote:

­^^^ This.

Also those pros may have been rehersing the route dozens of times. They would know pretty well what's likely to rotate and what's not. If it's your first time/few times on a route you likely don't. Odds are they also are way less clumsy in how they move pass their gear, therefore way less likely to make rushed moves that would help stuff rotate....

Yup, makes complete sense. I know with time you start to automatically read the rock and adjust systems/placements accordingly. I know that takes time on the rock and competent understanding of said skills and learned systems. Like what works and what won't, where you can cut corners and not die and the times you just have to say fuck it and go. New climbers will never have that understanding until it is learned and then experienced. So I learn on my anchor board, my backyard, gym, this bridge, with input from experienced climbers and when I can get out there apply everything I've learned and transform into muscle memory.

Totems won't rotate like that. You need to go buy a bunch of red and orange totems just for this crack.

abandon moderation wrote: Rotation doesn't matter in a splitter, which is why you see the pros doing that (and anyone else who climbs splitters). If you don't believe me, go take some falls in a splitter with the cam at stupid angles and watch what happens (backed up by something solid, of course)

If you do something non-standard (place a piece in a flare, against the back of the crack, etc) now rotation matters. If when rotation matters vs doesn't matter is too complex, you should probably spend more time following someone and cleaning gear, or at least spend some time falling on gear with a TR backup.

But cm'on, this is a perfectly parallel concrete crack. The only point to the op should be if the crack is shallow (often true in concrete cracks), don't place the gear against the back of the crack so that it can rotate when you fall. But that concrete is more solid than most sandstone.

Other than rotate, they sure didn't move, walk or creep. I know better than to place cams too deep and get them stuck or wedged in bad angle so they wouldn't rotate.  They did rotate back down easily and catch just fine under body weight. Didn't try a fall on them...yet.  After my experience and feeling out the placement, I wouldn't worry about the angles they were at.