As a dad, as a climber, and as a concerned person.

[Rad]

My son is 3.5 now and just expressing an interest in climbing. I haven't started him at all yet. I don't see a hurry. I want him to have fun, safe experiences.

 

I see no reason why kids can't get a lot of learning and experience TRing and following before they lead. Are you trying to train their lead heads!? How about math and science and history. I see no benefits for the increased risks of having kids lead - particularly at the changeover to lowering/rapping at the top.

 

For that matter, I think newbies head into leading too soon. Many could benefit from a lot more following and TRing first IMHO.

 

[Cairns]

I don't think they're able to understand consequences well enough at that age to make an informed dicision about what's an acceptable risk and what's not.

 

 

check out Allstate's dorsal lateral prefrontal cortex theory. I don't put the age bar quite that high but the one time I took 10-year olds climbing as a summer camp counselor I was very glad none of them ran off the top of the cliff chasing each other around.

[bstach]

I agee with some of the others responses over on climbing.com with regards to body size in using the chest harness as well as diamter of rope with regards to static falls with lower body weights. This all has to be taken into consideration.

 

The response about kids falling harder is nonsense. Force required to stop a climber has only to do with the mass of the climber and how far they fall and the stretchiness of the rope (which is constant). There is no way a greater force can be generated given the same fall distance by a lighter climber.

 

[catbirdseat]

I agee with some of the others responses over on climbing.com with regards to body size in using the chest harness as well as diamter of rope with regards to static falls with lower body weights. This all has to be taken into consideration.

 

The response about kids falling harder is nonsense. Force required to stop a climber has only to do with the mass of the climber and how far they fall and the stretchiness of the rope (which is constant). There is no way a greater force can be generated given the same fall distance by a lighter climber.

You are quite wrong about this. The force generated RELATIVE to the mass can be greater. The acceleration on the small climber can be larger than the acceleration on the larger climber.

[Bug]

My concern would be that the mass would be too small to put enough force on the rope to enable it absorb the force by stretching. Might it be like falling on a static line if the climber is too light?

[catbirdseat]

Ropes don't act like perfect springs which obey Hooke's Law. They obey a non-linear function. For small displacements, brought about by small masses, the force constant is higher than at larger displacements.

[bstach]

If the climber does not exert enough force on the rope to stretch it, the rope does not exert much force on the climber (as per Newton's third law). Am I missing something here?

 

I understand that the spring constant changes, that it takes more force to stretch the rope per unit length at small displacements....but the force also has to be small.

Edited September 20, 2007 by bstach

[Adam13]

That's the point when someone very light falls they can be falling much faster than someone of normal size before the rope strectches. The speed at which they fall is the same as a normal sized climber, but when the rope becomes tight and they stop without any stretch this results in higher G forces exerted on the person, i.e. higher risk of injury

[RuMR]

If the climber does not exert enough force on the rope to stretch it, the rope does not exert much force on the climber (as per Newton's third law). Am I missing something here?

 

I understand that the spring constant changes, that it takes more force to stretch the rope per unit length at small displacements....but the force also has to be small.

CBS did say "relative"...

 

I think a better way of looking at it, is that my fatass would prefer getting caught by a lighter climber than a brick shithouse. Conversely, my fat ass catching my little son's scrawny butt is gonna stop him pretty damn quick...ie its getting closer to a static anchor/belay.

 

I agree with cbs on this one.

[Choada_Boy]

That's the point when someone very light falls they can be falling much faster than someone of normal size before the rope strectches.

 

Hey Aristotle: They'd both be going the same speed.

[RuMR]

That's the point when someone very light falls they can be falling much faster than someone of normal size before the rope strectches. The speed at which they fall is the same as a normal sized climber, but when the rope becomes tight and they stop without any stretch this results in higher G forces exerted on the person, i.e. higher risk of injury

they are falling at the same velocity until the fall begins to be arrested.

 

the rope is a nonlinear spring (as cbs pointed out); both parties will follow the same stress-strain curve of the rope until a certain point at which time the smaller guy's fall will be arrested and the larger guy will continue straining (and therefore stressing) the rope further as he CONTINUES to decelerate.

 

The rope is a non-issue in this discussion as its constant to both climbers.

Edited September 20, 2007 by RuMR

[Choada_Boy]

It's as if climbing equipment isn't designed for six year olds....

[RuMR]

you'd think that...

[RuMR]

If the climber does not exert enough force on the rope to stretch it, the rope does not exert much force on the climber (as per Newton's third law). Am I missing something here?

 

I understand that the spring constant changes, that it takes more force to stretch the rope per unit length at small displacements....but the force also has to be small.

[Choada_Boy]

Any increase in applied forces would be offset by the flexibility of the child's undeveloped bones. That's why six year old lead climber's don't need to wear helmets.

[Adam13]

I said the smaller person could go faster before causing stretch in the rope. Read a post more carefully next time before you want to repond to it.

[Adam13]

The rope isnt a non-issue because it will stretch and slow the descent of a heavier climber when it will become taught and jerk instantly when encountering a lighter climber, they both use the rope but it doesnt react the same way.

[Choada_Boy]

I said the smaller person could go faster before causing stretch in the rope. Read a post more carefully next time before you want to repond to it.

 

After not carefully reading or re-reading your post, I still think you're retarded. They would both be going the same speed when the rope began to stretch. The rate of rope stretch would be different. That is how I "repond", Aristotle.

[Adam13]

I didn't say that they would be going faster fuckstick, I said they could go faster before causing rope strectch, it seems you are the one too retarded to understand words.

[Choada_Boy]

Me no speak retard, maybe that's why I can't understand you.

 

The rope will stretch instantly, at different rates, for both climbers, who would be traveling at the same speed. And wood is not made of "Earth" and "Fire", Aristotle.

[Adam13]

Nothin happens instanty. You know far too little about science to lecture me. The thousanths of a seconds in difference when an object comes to a stop can be the difference between being shaken up and being bagged up.

Keep calling me Aristotle, it only shows how fucking stupid you really are.

 

 

[Couloir]

Love is in the air!

[Adam13]

It is my fault, I shoulda made my statement more clear so those of us with less developed brains could understand what i was trying to say, sorry Choada.

[racsom]

I don't quite understand this quote.

 

Ropes don't act like perfect springs which obey Hooke's Law. They obey a non-linear function. For small displacements, brought about by small masses, the force constant is higher than at larger displacements.

 

 

For all practical purposes most materials behave in a linear fashion under "normal" loads. Non-linear effects are only taken into account if it is reaching a load big enough to show non-linear effects (i.e. fracture, etc). Are you saying that the strain-stress curve of climbing ropes is say something that looks like a quadratic function?

 

 

You have any source to back this up? A quick search in google and I couldn't find a strain-stress curve of ropes. I didn't search the rope companies.

 

In any case, even if the ropes are non-linear or linear, the small child will feel a higher acceleration due to the fact that he is not carring enough momentum to make the rope stretch.

Edited September 20, 2007 by racsom

[RuMR]

The rope isnt a non-issue because it will stretch and slow the descent of a heavier climber when it will become taught and jerk instantly when encountering a lighter climber, they both use the rope but it doesnt react the same way.

no dumb ass...they both track the same stress-strain function to a point at which time they diverge (one quits straining, the other continues).