Try some of these for more info:

Petzl shock load page

**Re: Fall factors and forces involved **

Author: Tony Bubb

Email: Bubb@xxxxxxxxxxxx

Date: 1997/05/01

Forums: rec.climbing

Mike Garrison wrote:

>

> Mike Kubicka wrote:

> >

> > I'm doing a physics project for school involving fall
factors, forces in

> > a fall on protection and the climber, and how dynamic
ropes affect these

> > forces. I've already read the Petzl catalog, but I was
looking for some

> > more in depth information. Thanks in advance for any
help.

>

> It's a pretty simple problem. Why not solve it for yourself?
Physics is more

> fun that way.

Yeah, really simple, sure. Just do the math, 100's of ignorant

rec.climbers have done it before. Oh... as a side note, nobody

has been very close yet.

Fall factor is not the dominant system in short falls? Know
why?

Hint: Model the human spine and hips into the equasion. Simple

math really!

-T.

**Re: Fall Forces when belayer runs downhill **

Author: Clyde Soles

Email: Clyde_Soles@xxxxxxxxxxxx

Date: 1995/04/15

Forums: rec.climbing

In message ID <503-QB7.jwadsworth@xxxxxxxxxxx> on 4/15/95,

jwadsworth@delphi.com wrote:

> Apparently no physicists read this, and no one who replied
has studied the

> puysics of climbing.

Maybe, but what is your excuse?

> Remember this simple formula: Impact Force = Distance

> fallen divided by rope paid out. More simply, this means
if you take a 20 foot

> fall on ten feet of rope, you get an IF of 2.

> If you take a 20 footer and your belayer reels it in to 5
feet of rope, you get

> an IF of 2.5.

Non sequitor. First off, impact force and fall factor (what
is described above)

are not at all the same thing. It is impossible to generate a
fall factor

greater than 2, no matter what you do. (You can't even achieve
2 in the real

world but we won't get into that) Think about it. If you have
10 feet of rope

out and the belayer takes in 5, you cannot fall 20 feet without
cutting the

rope. Impact force is determined by numerous factors including
the amount of

rope out, rope characteristics, mass of climber, and quality of
belay.

**Re: Fall Factor Math - Was Need Help Phys/Engr **

Author: BillFoote

Email: billfoote@xxxxxxxxxxxxx

Date: 1995/04/19

Forums: rec.climbing

Anthony Bubb replied directly to author and wrote (paraphrased)

|> No... the rope will exceed the elastic limit and go into
plastic

deformation...

I would suggest that if a rope is designed to withstand a factor-2
fall,

then it will not reach it's elastic limit (yield point) when loaded
below

that factor-2 force, so the analysis should be fairly correct
in that load

range.

If the rope DOES go into plastic deformation, it is in the
process of

failing. OK, it might in a really bad fall (factor 2 perhaps),
but as

illustrated below

the max forces calculated should still be conservative numbers.

As shown below, (QUALITATIVELY), when a material reaches it's
elastic

limit, or yield point, Y, the stress-strain curve levels off.
The slope

of the curve shown below is the material's Modulus of Elasticity,
or the

reciprocal

of the "spring constant" k used in my analysis. So,
as the material

is loaded beyond Y, the change in the slope (modulus) will result
in the

actual forces being less than those calculated using the original

equation.

(The equation assumes a straight line stress-strain relationship).

As originally stated, this is a CONSERVATIVE analysis, and
ACTUAL forces

should not exceed the values produced by this equation. This is
not to

say

that the effect on the rope is less severe. Exceeding the elastic
limit

means severe damage to the rope, and it should be retired!

| *<-results from the provided equation

| *

| *

| * + U = ultimate strenght

(breaks here)

| * +

| * + ^

| * + |__ more realistic stress-strain curve

| * Y

| *+

Force | +

(stress) | +

| +

| +

| +

|+

+----------------------------------------------------

Stretch

(strain)

BillFoote@xxxxxxxxxxxx

P.S. A interesting thing to note: According to this analysis,
there is no

difference (impact force - wise) between a 2-foot factor-2 fall
and a

160-foot factor-2 fall, or a 2-inch factor-2 fall!

Should a rope be retired if one, for example, falls 4 inches
with only 4

inches of rope paid out? THIS IS A FACTOR-2 FALL!!!

**Re: Fall Factor Math - Was Need Help Phys/Engr **

Author: Anthony R Bubb

Email: bubb@xxxxxxxxxxxxxxx

Date: 1995/04/19

Forums: rec.climbing

billfoote@aol.com (BillFoote) writes:

>Anthony Bubb replied directly to author and wrote (paraphrased)

>

>|> No... the rope will exceed the elastic limit and go
into plastic

>deformation...

>

>I would suggest that if a rope is designed to withstand a
factor-2 fall,

>then it will not reach it's elastic limit (yield point) when
loaded below

>that factor-2 force, so the analysis should be fairly correct
in that load

>range.

Why do you think it only survives a certain number of them???

>If the rope DOES go into plastic deformation, it is in
the process of

>failing. OK, it might in a really bad fall (factor 2 perhaps),
but as

>illustrated below

>the max forces calculated should still be conservative numbers.

No, if you say teh spring can extend infinitely without limit,

then you may continue elastic deformation linearly until the fall

energy is absorbed. If you consider an elastic limit, the force

may curve upward exponetually until you are in a purely plastic

region. The force may well exceed the calculations you've done,

and the result is that your estimates were NOT conservative.

>As shown below, (QUALITATIVELY), when a material reaches
it's elastic

>limit, or yield point, Y, the stress-strain curve levels off.
The slope

>of the curve shown below is the material's Modulus of Elasticity,
or the

>reciprocal

>of the "spring constant" k used in my analysis.
So, as the material

>is loaded beyond Y, the change in the slope (modulus) will
result in the

>actual forces being less than those calculated using the original

>equation.

Just before that point, you may get quite a swell though,

Like a function that approaches some huge value (parabolically)

The problem is that much of the "springiness" of
the rope comes

NOT from the material, but from the WEAVE. This WEAVE can only

re-align so far before it's at it's max.

An example. A BW 10.5mm enduro stretches about 7% under an
80kg

mass load ( aprox 170lbf) Do you think that under 1700lbf it will

stretch 70%?!?!?!?! Now, what about the 2200 lbf you predicted?

Do you think the rope will stretch 91%?!?!? No, it won't.

The "spring" gets stiffer as you go, and all linear
approximations are

irrelivant and wrong.

>As originally stated, this is a CONSERVATIVE analysis,
and ACTUAL forces

>should not exceed the values produced by this equation. This
is not to say

>that the effect on the rope is less severe. Exceeding the
elastic limit

>means severe damage to the rope, and it should be retired!

Yup. Not that on tests by the UIAA, after the first or second
fall,

that the impact forces exceed safe limits.

> (ascii art nice, but not relivant)

>

>P.S. A interesting thing to note: According to this analysis,
there is no

>difference (impact force - wise) between a 2-foot factor-2
fall and a

>160-foot factor-2 fall, or a 2-inch factor-2 fall!

We get into system dominant effects. A knot and your body

can absorb most of a 2ft fall, but are insugnificant in a 200'
fall.

>Should a rope be retired if one, for example, falls 4 inches
with only 4

>inches of rope paid out? THIS IS A FACTOR-2 FALL!!!

No, system domination achieved by spinal compression.

I did some rough calculations on this 2 years ago, and again last
fall.

They were posted.

-T.

**Fall Factor Math - Was Need Help Phys/Engr **

Author: BillFoote

Email: billfoote@xxxxxxxxxx

Date: 1995/04/18

Forums: rec.climbing

ASpencerS (aspencers@aol.com) wrote:

|> Calling all rock climbing physicists

|> Impact Force

|> In Cimamondís book ìClimbing Rock and Iceî

|> He describes Impact force as

|> I = mg + mg sqroot(1+ 2fM/mg )

|> Were

|> I = impact force in ft-lb/sec2

|> M= rope modulus in Ft-lb/sec2

|> f= fall factor (distance fallen /amount of rope paid out
)

|> g= acceleration constant of gravity ( 32 ft/sec2)

|> m = mass

|> He goes onto say that a 180 pound climber falls onto
a top rope with no

|> slack he generates 360 pound of force (this must refer to
the top anchor

|> on a social belaye or lead ) he go on to state a fall factor
of 0.4, 0.8,

|> 1.0, 1.4, 1.6, and 2.0 would generate forces of 1137; 1521,
1676; 1947;

|> 2067; 2288; pounds of force respectively.

|> for compete text refer to cinamons Climbing Rock and Ice
pg. 157 -159.

|> I attempted recreate his calculations with no avail

|> I was unable to factor in M-Rope Modulus

|> What I was attempting to create was a spread sheet that
would have length

|> of fall on one axes and amount of rope played out (say in
5 ft incments)

|> on the other axes. Given rope stretch of x percent say 7%
you could

|> conceivably form a matrix of impact forces

|> Can any one give me some help with this excercis on how
to use this

|> formula in a spread sheet. It may help others understand
impact forces

|> and how they differ as rope is played out.

|> Thanks Spencer

Reading so much talk on fall factor, whether to run uphill,
downhill,

sideways, "what if..." , etc., I was interested to know
if the maximum

force in a fall could REALLY be correlated to fall factor. So,
here is

my attempt to answer my own question... just thought some of you
may also

be interested.

Mathematics of the Fall Factor

This analysis is a simple derivation from first principles
of the maximum

force |> generated in a fall as a function of Fall Factor and
other

parameters. Several simplifying assumptions are made which include:

* The rope is treated as a simple spring, and no attempt is
made to

account for energy absorption in the rope, or dampening, which
really

only results in this analysis yielding LARGER than actual maximum
forces.

* Does not account for energy absorbed by either the belayer
or fallen

climber, both of which will also reduce the actual maximum forces

generated.

Both of the above assumptions make this a CONSERVATIVE analysis,
meaning

that actual forces ON THE ROPE will be less than those

calculated here. However, these are just the forces on THE ROPE,
not on

the pro, and not concentrated by a knot.

The following notations will be used:

L = rope length (rope paid out before stretching)

l = rope stretch

S = %stretch = l / L

d = distance of fall, NOT INCLUDING stretch

F = fall factor = d/L

m = mass (of fallen climber)

g = gravitational constant

W = weight of climber = m * g

K = spring constant, force per unit length

k = K / L = spring constant per unit length or force per length per length

Z = max force

The analysis basically uses the concept of conservation of
energy,

assuming that the potential energy difference between two different

heights will be equal to the energy stored in the rope (assumed
to behave

as a simple spring).

Potential energy = Energy stored in spring

m * g * h = 1/2 * K * x * x

W * (d + l) = 1/2 * (k / L) * l * l (fall + stretch)

W * (d/L + l/L) = 1/2 * k * (l/L) * (l/L)

W * (F + S) = 1/2 * k * S * S

The max force on the rope is Z = K * l = (k / L) * l = k * S

W * (F + Z/k) = 1/2 * Z * S = 1/2 * Z * Z / k

or

2 * W * F * k + 2 * W * Z = Z * Z

Z * Z - 2 * W * Z - 2 * W * F * k = 0

using binomial equation to solve,

Z = (2 * W +/- sqrt(2W * 2W - 4 * (-2WFk))) / 2

Z = W + sqrt(WW + 2WFk)

So, we have all the necessary information to correllate maximum
force Z to

fall factor F, except the spring constant k.

Looking at rope specs in a gear catalog, I found that climbing
ropes

stretch anywhere between 4% and 8% under an 80kg load.

therefore, by my notation, k = 80 kg / s, where here lower
case s is %

stretch for 80kg.

Z = W + sqrt(WW + 2WF(80 / s))

Z = W + sqrt(WW + 160WF / s)

For an 80kg climber (about 176 pounds) here are some results
from that

calculation:

F s Z(kg) Z(lb)

1 8% 488 1073

1 4% 651 1433

2 8% 651 1433

2 4% 884 1945

2 2% 1214 2671

2 1% 1682 3700

2 0.5% 2344 5157

Now a couple of extra comments... notes.

1) As stated, for most dynamic climbing ropes, s=4% to 8%.

2) I have no idea what s is for webbing or static line, but
probably down

in the range 1% or less.

3) Once again, this is the force on the rope (or more precisely,
the

fallen climber). Knots will concentrate the force.

4) If the climber is belayed through a piece of pro, and assuming
the

biner acts as a perfect frictionless pulley (it's really not),
the force

on the climber must be opposed by the belayer. Therefore the total
force

on the PRO is 2X!. As someone suggested on this thread,

ROPES DON'T BREAK! People and placements DO!

Just food for thought

Flames welcome. I'd like to know if I've made any horrible
mistakes.

But, I think you'll find that it's equivalent to the formula provided
by

ASpencer.

BillFoote@xxxxxxxxxxx

**Fall Factor: Summary and corrections **

Author: Anthony R Bubb

Email: bubb@xxxxxxxxxxxxx

Date: 1995/04/17

Forums: rec.climbing

>Clyde Said:

>It is impossible to generate a fall factor

>greater than 2, no matter what you do. (You can't even achieve
2 in the

>real world but we won't get into that)

Casey Boyce Replied:

WRONG!!! Say you're at a belay, and your partner starts up a climb.

He's just about to clip into the first piece of pro, when, slip--he's
off.

He falls back to the belay, and as far below the belay as he was
above

it. Do the math & it works out to fall factor 2. (say 10 ft.
above the

belay. this means a 20 footer, and 20/10=2) It is also possible
to

generate falls above factor 2, but I forget how (possibly by taking
long

falls on static rope?). See the Petzl ad for more info.

Casey Boyce

--------------------------------------------------------------------

Casey,

Why is Clyde wrong?

OK, so how about 2.0?!?! Well, was there NO

rope below the anchor? Were you belaying the leader

dircetly off of it!?!?!? SHeesh... I'll stick with

my regular climbing partners!

-----------------------------------------------------------------------

: SOmeone said:

: Shortening rope is a Bad Idea, period. You should be placing
enough pro to

: prevent groundfall in the firstplace, & by shortening rope
you increase the

: liklyhood of ripping out you gear.

Chuck Replied:

Taking in rope during a fall will reduce the amount of rope available
to

absorb the fall but it will also reduce the length of the fall.

If you are expecting a fall of less then factor 1.0, taking in
rope will

reduce the fall factor.

If you are expecting a fall of factor 1.0, taking in rope will
have no

effect on the fall factor.

If you are expecting a fall of more then factor 1.0, taking in
rope will

increase the fall factor.

---------------------------------------------------------------------

Essentailly the thread we had 2 months ago. Genearlly

correct, but again, TAKING IN rope is NOT the same as

RUNNING with it. (Which was the issue at hand.) You

aren't setting a large inertia in motoin the other way...

------------------------------------------------------------------

In article <503-QB7.jwadsworth@xxxxxxxxxxxx> jwadsworth@delphi.com writes:

>Apparently no physicists read this, and no one who replied
has studied the

>puysics of climbing.

---------------------------------------------------------------------------

Not you either eh? Crap, my little sister (12) could tell

you what was wrong with your analysis. I'll give you her

Email address if you want to discuss it with her.

---------------------------------------------------------------------------

>Remember this simple formula: Impact Force =

>Distance fallen divided by rope paid out.

--------------------------------------------------------------------------

Forget that. The only thing simple here was the poster.

--------------------------------------------------------------------------

>More simply, this means if

>you take a 20 foot fall on ten feet of rope, you get an IF
of 2.

>If you take a 20 footer and your belayer reels it in to 5
feet of rope,

>you get an IF of 2.5.

-------------------------------------------------------------------------

This analysis is _SOOOO_ wrong, I am not even going to

bother with it point by point. Just ignore it. It is

flawed in every fundimental sense possible.

-------------------------------------------------------------------------

>Any impact force of more than 1.5 can cause whiplash or break
a few bones of

>the climber, as well a rip gear right out.

------------------------------------------------------------------------

First of, all you're talking FALL FACTOR, not impact force.

Not! If the rope has not lost dynamic charactoristics, it

should not be as severe as implied. UIAA dictates that a

rope must survive the FF= 1.78 without a max impact force

over what a human can survive. That's not to say injuries

can't happen, but really...

-------------------------------------------------------------------------

>Shortening rope is a Bad Idea, period. You should be placing
enough pro to

>prevent groundfall in the firstplace, & by shortening
rope you increase the

>liklyhood of ripping out you gear.

SOmeone else replied:

a common mistake in several of the responses in this thread is
the thinking

that running downhill shortens the rope length. It doesn't! Only
taking in

rope through your belay device can shorten the rope. Think about
it a little.

----------------------------------------------------------------------------

Amen. Don't confuse the two... inertial diffs. again.

----------------------------------------------------------------------------

>The old "dynamic hip belay" of pre-belay device
times was safer in terms of

>impact force generated. This involved feeding rope out, not
shortening it.

>Summary: DON'T shorten rope, run downhill, etc. You will probably
cause more

>harm by doing this.

------------------------------------------------------------------------------

There is a second issue being ignored. The attached file at the

end of this post discusses "Short-Roping" in detail.

-----------------------------------------------------------------------------

>Read the two page ad on safety that petzl has recently printed
in Climbing

>Magazine if you want a better expanation of the physics involved.
John Forrest

>Gregorys Rock Sport also explains it well.

-------------------------------------------------------------------------------

Hopefully far better!

------------------------------------------------------------------------------

DTWS46B@xxxxxxxxxxxx (Casey Boyce) writes:

>> Clyde Wrote:

>> It is impossible to generate a fall factor

>>greater than 2, no matter what you do. (You can't even
achieve 2 in the

>>real world but we won't get into that)

> WRONG!!! Say you're at a belay, and your partner starts
up a climb.

>He's just about to clip into the first piece of pro, when,
slip--he's off.

>He falls back to the belay, and as far below the belay as
he was above

>it. Do the math & it works out to fall factor 2. (say
10 ft. above the

>belay. this means a 20 footer, and 20/10=2) It is also possible
to

>generate falls above factor 2, but I forget how (possibly
by taking long

>falls on static rope?). See the Petzl ad for more info.

malley@xxxxxxxxxxx replies:

I think your right. Suppose you're 10 feet up from the belay and

fall. The belayer is on top of things and decides to take in as
much rope

as possible before you weight the rope. Suppose he takes in 3
feet. The

leader will fall the 10 feet to the belay, and then 7 more feet
to the end

of the rope. He has taken a 17 foot fall and there is only 7 feet
of rope

out when the fall stops. Fall factor = 17/7 = 2.43. Is this right?

----------------------------------------------------------------------------

Possible, yes. assuming that the FF= 2.0 was possible to

start with. How were you belaying in the first place though???

See prior comment. FF = 2.0 shouldn't be happening!

------------------------------Attatched File--------------------------------

Short-Roping the leader (a blue-print for injury).

This applies to sport-climbing, primarily, and more to overhangs
than

anything else, though the same will be true of dead-vertical climbs.

Slightly slabby stuff DOES NOT APPLY TO THIS REASONING.

Simply put:

Given a lead fall of a certain lenght, there are several

possibilities. These amounts of "slack" are not the
distance between the

climber and last piece of pro. They are the EXTRA rope payed out,
or

"looseness" of the system.

#1) No slack in the rope (rope is almost tight before fall).

#2) A bit of slack in the rope (say 2').

#3) A LOT of slack (say, 5' or more) in the rope.

#4) SHORT_ROPING The belayer takes rope or puts on tension before

or durring a fall. THIS IS BAD!

In case #2, what you will have under normal circumstances,
the leader falls

a bit, and is yanked to a stop below his pro. Normally, this is
not a problem,

but may be less than ideal at times, with the leader being swung
into the

cliff somewhat.

Case #1 Is not quite short-roping , but is almost as bad. In
this situation,

the leader has progressed up what we'll assume to be a constant
incline

(overhang, I guess) on the cliff. (s)he is now a certain vertical

distance and horizontal distance above the pro. WHen the leader
falls,

they will come onto tension just slightly further out than they
started

(due to "popping" off of the cliff), then proceed to
be swung/catapoulted

into the wall at about the same distance on the other side of
the pro...

I.E., right into the cliff. Pull back a swing a certian distance,
it will

swing about the same amount the other way. Applies (though not
ideal,

probably better than a swing) to climbers as well.

Case #4 Is SHORT_ROPING. The climber ends up falling less PAST
the pro than

(s)he started above it. IE, climber is 4' above the pro, and 2'
of rope

is taken in. In a high-factor fall, the leader might stop 3' below

the pro after rope stretch (2' if you don't count it). Well, let's
say it was

a 45 degree angle cliff. Now you're 4' OUT from one side of your
pro, plus

a foot or two (we'll say 2) because you "popped"; this
totals a horizontal

distance of 6 feet out. The cliff is only 3' on the other side
of the bolt.

Guess who gets slammed into the cliff.

It could be worse yet. Say, for example that your belayer DID
put tension

on the line as you cruised past the last piece of pro... No you
have an

added inward accelleration. DUMB! Smack, evolution isn't always
working

like it should. The belayer makes the error, and the leader pays.

SO, the ideal situation could be either #2 or #3. The main
point is that

the leader is further than twice the distance from the cliff when
the rope

comes tight than (s)he started out horizontally from the pro.

Someone also mentioned jumping out from teh cliff when they
fall. On

overhangs and verticals, I'd say it's a raw deal. Don't do it.
You'll

get slammed in with an equal amount of energy added. Fall vertically.

On slabs, it will "depend" upon the fall. If you think
you can avoid

impact that way, go for it, if not, slide!

Obviously, you don't give or allow slack if there is a ledge
coming up.

The math was greatly simplified for the sake of brevity. Flame
me if you

really want to, but all it's gonna get you is ridicule and possibly
a more

elaborate model. Yes, I could do an energy analysis, but it's
gonna yield

about the same #'s. Different amounts of overhangs produce the
same effect

to varrying degrees, and I'll just let you guys figure out vertical
walls

by yourselves (which you are capable of). Swing a pendulum of
given mass

and initial horizontal displacement on a long string then a short
string

to see what collides more violently with a wall, and you have
a perfect

example of what happens on vertical-climbs if short-roped.

Hope this helped, but I know I didn't do the best job explaining
it all.

I'll welcome net.discussion on this subject matter (won't fire
the

flame thrower up except to retaliate), as I believe it's appropriate

material for this news group.

So... Any questions?

-T.

**Re: Force of a fall? **

Author: Kenneth Cline

Email: cline+@xxxxxxxxxxx

Date: 1995/08/17

Forums: rec.climbing

In article <40vt2b$1s3m@rover.ucs.ualberta.ca>, cscobie@gpu.srv.ualberta.ca
(Corey Scobie) writes:

|> I was wondering if anyone could supply me with the correct
procedure to

|> determine the force of a fall (math equations). I am going
to trivialize the

|> question a little with the following stipulations:

Oh, no.

Everybody duck! We're in for another round of bad physics...

Please: If you feel compelled to respond to this question be

absolutely sure that any technical discussion is correct. I hereby

offer to proofread articles for technical content before posting.

I also threaten to savagely flame anyone who gets it wrong.

The simple answer to the questions posed is that despite numerous

discussions of the physics of falling on rec.climbing, we don't

know. I can assure you that a rope is more complex than a spring.

It is also clear that for a given rope, fall force is positively

correlated with fall factor, the ratio of distance fallen to length

of rope absorbing the fall. Similarly with climber's mass.

Note that ropes absorb energy by several different means, including

stretching of individual fibers, tightening of yarns and braids,

friction between fibers, and probably others that I have

overlooked. Manufacturers design their ropes to act differently
at

different loads.

Ken

**Fall factor spec. **

Author: David T. Wilson

Email: dtw@xxxxxxxxxxxx

Date: 1997/03/30

Forums: rec.climbing

I had requested some information on what a UIAA FALL is and
I had one

reply then founf it in a book I had over looked so I thought I
would

pass it on .

The drop Test.

In a climber's eyes the drop test is the most critical test
that could

be made. This test is designed to simulate a leader fall. The
UIAA

measures both the ropes impact force and the number of falles
a rope

can with stand.

To conduct the test, The uiaa anchors one end of a 2.8 meter
length of

some manufacturers rope, which they run through a carabiner-like

device. Next they load its free end with either an 80kg. load
(if

they are test a single rope), or a 55kg. loAD (FOR ONE DOUBLE
OR TWIN

ROPE). They also test two double and twin ropes at a time, dropping

the 80kg. weight.

The anchored end is 0.3m away from the carabiner-like device,
so the

actual lenght of the slack rope is 2.5m. The loadis dropped from
this

hight, and ends up falling a bit more than 5 meters, due to the
rope's

stretch. The result is a fall factor of 1.78.

In order to pass the test, a single rope must have an impact
force of

less than 12 kilo newtons, and with stand at least 5 falls befor
it

breaks. A double or twin rope must rigister an impact force of
less

than 8 kn., and with stand at least 5 falls.

Taken from Rock Gear by: Layne Gerrard

**Re: Fall factor spec. **

Author: Clyde Soles

Email: csoles@xxxxxxxxxxxx

Date: 1997/04/01

Forums: rec.climbing

David T. Wilson <dtw@xxxxxxxxxxx> wrote:

Just to set the record straight, your source is a bit misinformed.

> The drop Test.

> In a climber's eyes the drop test is the most critical test
that could

> be made.

Should read, "In the uneducated climber's eyes..."
Fall ratings are

about the least valuable bits of info when deciding on a rope.
Great

marketing tool though.

> They also test two double and twin ropes at a time, dropping

> the 80kg. weight.

Only the twin, not the half rope.

> The result is a fall factor of 1.78.

Close enough. It's really 1.73. Still very severe.

**Re: Fall Factors **

Author: Clyde Soles

Email: csoles@xxxxxxxxxx

Date: 1997/04/01

Forums: rec.climbing

D B FRAZ <dbfraz@xxxxxxxxxx> wrote:

> Any rope manufacturer will tell you that

> there ropes will take hundreds if not thousnads of factor
.166 falls.

No, they won't. Bluewater has done tests which showed repeated

low-factor falls results in significantly lower tensile strength
and

higher impact forces. This is something which is not practical
to create

a standard for due to the very high costs of testing. There is
also the

problem of the sheath wearing out roughly fifteen feet from the
end on

ropes used for taking lots of wingers -- hence the reason behind

"Program" and gym ropes. Ropes also deteriorate with
age somewhat, even

when sitting in a wrapper.

You might educate yourself a bit more before calling everyone
else

idiots. There is no easy answer on when to retire your ropes from
lead

duty.

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