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Calibrating Lifeline Chest Expander Cables - An Experiment

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#121 [url]

Jun 6 11 10:44 AM

ayeedee wrote:
Lifeline states the poundages for the different strengths of tubing they sell. For example the blue 60'' tubing is rated at 90 lbs when stretched to 72'' The same poundage is given for the 16'' blue chest expander tubing.How can this possibly be? Look at the graph given in the training guide pdf.    http://www.lifelineusa.com/files/Lifeline_CableExercises.pdf
Being basically slow,  I'm beginning to think this is where the confusion may have originated.  The Chest Expander page showing pullweights which are for the long cables, by mistake.
Still doesn't excuse Lifeline's continued silence and indifference to someone who is only trying to help them as well as its customers. It would only take a few hours to test all their Chest expander cables, if that.
Kevin Dorsey's url in his post shows the Long cable pullweights and testing methods.  Do Lifeline not understand plain English,  or the difference between their own short cables and long cables ?
As Marketing Manager,  I would have thought he would have an intimate knowledge of the full range of Lifeline products, being responsible for marketing them.  Even he doesn't seem to understand the difference between a 16" Chest expander cable,  and one of the longer models.  

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#122 [url]

Jun 6 11 11:30 AM

Macky, since you have that nice pull gauge, can you measure a same color short and long cable at (the new) 3x length and see how they compare?

I'm guessing that LL is assuming that a cable at 3x length will always have the same tension regardless of its length. I don't know the properties of rubber well enough to say that's true.

As for the way they measure on their diagram. If you measure both handles, it gives the Tension in the cable, so that is correct. I've read some strand pulling texts that say if you do a pull at a certain weight that its pulling the same amount in the other hand. That would be the one handle measurement. That is more a problem of terminology, and how you want to look at it. Measuring tension in the cable always means the same thing however, its the total pull on both ends, for our purposes 2x the one handle measurement.

Well i guess you could also measure that to see it its true in real life, measure one handle and two and see if its really twice the pull.

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#123 [url]

Jun 6 11 2:07 PM

MrBrady wrote:
Macky, since you have that nice pull gauge, can you measure a same color short and long cable at (the new) 3x length and see how they compare?

I'm guessing that LL is assuming that a cable at 3x length will always have the same tension regardless of its length. I don't know the properties of rubber well enough to say that's true.

As for the way they measure on their diagram. If you measure both handles, it gives the Tension in the cable, so that is correct. I've read some strand pulling texts that say if you do a pull at a certain weight that its pulling the same amount in the other hand. That would be the one handle measurement. That is more a problem of terminology, and how you want to look at it. Measuring tension in the cable always means the same thing however, its the total pull on both ends, for our purposes 2x the one handle measurement.

Well i guess you could also measure that to see it its true in real life, measure one handle and two and see if its really twice the pull.
I certainly would do that if I had any long cables MrBrady.  But I only bought a set of Orange chest expander cables with soft handles.

I think we can all get caught up in too much complicated physics,  and end up missing out on what is relevant, and what is not.

When you pull out a FCP or OHPD or Front/Back Press to full stretch,  the 100lbs ( e.g. ) tension on the cable puts 100lbs on each arm,  not 50lbs each as one would first imagine.  It's not like a barbell press overhead where each arm is working towards the same direction, therefore share the 100lbs between them.  
It follows that if one end of a cable is stopped firmly and the other end is attached to a scale and pulled out to where the scale registers 100lbs,  then the stopped end has 100lbs pressure on it as well.   That does not mean to say that the 100lbs tension generates 200lbs,  only that each end of the cable has 100lbs tension on it.

Lifeline state repeatedly that their Chest expander cable pullweights are determined at twice the cable resting length,  therefore the 16" cable is stopped at one end,  and the other end is stretched to 32" length with a scale measuring the tension,  then the poundage registered is posted for that cable colour.

Lifeline could only have done some 5 things with their Chest expander cables
1.  Never have measured their Chest expander cables,  because they would then have seen that the tests that Fatman and myself did were correct, and Lifeline were wildly out in their pullweights.
2.  Measured the chest expander cables but made fundamental errors.
3.  Measured the chest expander cables correctly but decided to ignore the true figures and post BS pullweights.
4.  Measured the chest expander cables for three cables all up correctly,  but somewhere in between the testing department and the page presenters the story changed from pullweights for three cables together, to single cables. 
5.  Measured the LONG cables and posted up the same results on their chest expander page.
 
Whichever one of these that Lifeline did,  I cant believe their utter incompetence.  They are either incapable of using a simple scale,  or their internal communication is non-existent,  or their ability to distinguish between their Long cables and their Chest expander cables is totally up the creek ( something that has been evidenced by Kevin Dorsey's post where he url's Lifeline's Long cable pullweight list and testing methods. )

That is why I suspected that Lifeline was deliberately falsifying its chest expander pullweight ratings and advertising them, because I also could not believe why out of 30-odd people, not one of them could organise a two-hour slot in the next day/week/month to test what I've been telling them for the last 15+ months.  As I've said before,  Lifeline have never refuted or denied my test figures,  in fact NOBODY whatsoever has replied to my 3 and 18 May emails, or my last emails from last year.  So what was I to think ?

To my mind,  the only reason why Lifeline has done so well is not because it makes such good quality equipment,  it's because most other's gear are so shitty.  Price as well, I suppose.

 
  

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#124 [url]

Jun 6 11 2:36 PM

Macky you are mistaken about Tension, this is a well defined thing, the sum of the forces acting on the cable, in this case the pull from the two handles. In strand pulling the Tension is always twice the pull on one handle.

So when you use your meter to measure a pull by attaching to one fixed point and attaching the meter to the handle, you are measuring the pull the handle exerts on the cable. The wall pulls back an equal amount. Lets say you measure a pull of 25lbs then the wall is pulling that much as well and the total tension is 50 lbs. because the handle and the wall are both acting on the cable. Its an extension of Newton's famous law, for every action there is an equal and opposite reaction.

You are right though, the way they are measuring is for a different situation, i was getting ahead of myself assuming they were trying to measure tension, sorry. In the lifeline diagram the Tension will be double. They are applying that result to the cables, which i'm not sure is really possible, but the only practical way to confirm this is to measure. There is the added confusion of measuring one hand vs two, they are going with two obviously and tension vs pull force. (of course in the LL example the legs and core also have to provide the opposite force so again there is the sam force on the feet side, in a way just like a pull)

I would love it if Lifeline could verbalize the process a little better, but honestly i don't think 99% of their customers care.

Last Edited By: MrBrady Jun 6 11 3:55 PM. Edited 3 times.

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#125 [url]

Jun 6 11 6:48 PM

MrBrady wrote:
Macky you are mistaken about Tension, this is a well defined thing, the sum of the forces acting on the cable, in this case the pull from the two handles. In strand pulling the Tension is always twice the pull on one handle.

So when you use your meter to measure a pull by attaching to one fixed point and attaching the meter to the handle, you are measuring the pull the handle exerts on the cable. The wall pulls back an equal amount. Lets say you measure a pull of 25lbs then the wall is pulling that much as well and the total tension is 50 lbs. because the handle and the wall are both acting on the cable. Its an extension of Newton's famous law, for every action there is an equal and opposite reaction.
 
I will assume that "Tension" and "Pullweight" are one and the same thing.  This is an interesting debate.
Smile  I cannot believe that a pull registering on a scale as 25lbs is in fact 50lbs total tension on a cable, otherwise the scale would register 50lbs.
Whether the cable is being pulled in the opposite direction,  or is fixed,  the moment the scale registers 25lb then the force at the other end is also 25lb.   The cable has 25lbs tension on it,  not 50.   How can this not be so ?  The scale is not measuring one handle's pull,  it's measuring the entire length of the cable.  How could the scale segregate a straight cable and register 25lb when the cable had 50lb "total tension" on it ?  When a one ton log is suspended steadily on a crane cable there is not two tons of tension on the cable.  There is one ton.

Take a 25lb barbell plate for example.  Pullweight is pullweight,  whether applied by gravity or muscle.   Hang the barbell from a fixed bar by a rope with a scale attached.  Apart from the extra possible weight of the rope,  the scale registers 25lb, right ?   It jolly well should,  if the barbell plate has 25lb stamped on it.  On the supporting bar there is 25lb of force being exerted,  correct ?  On the rope there is 25lb of tension exerted.  How can there possibly be 50lb ?   The scale would register 50lb if there was.   Whether the cord is stretchy like a expander cable or like a rope doesn't matter.  Once the scale measures 25lb,  that's it.  25lb tension on each end and on the cable.

That's why I said that if you pull out to full stretch FCP a cable with 100lbs tension on it,  each arm has 100lbs pulling inwards on it,  not 50lbs each as there would be if your assertions were correct.   The arms are opposing each other, not pushing in the same direction as in a typical weight training move.  That's also why Strand-pulling makes you so strong in the upper body.   You're doing better than you think Smile






  

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#127 [url]

Jun 6 11 7:38 PM

You are correct Macky! I just dug out my old college physics book ( i kept it for situations just like this!)


I am guilty of overthinking the problem! The weight you measure with the scale is indeed the tension, and both hands will work that amount.

This does indeed mean that Lifelines method of measuring is way off for strand pulling., they are doing the equivalent of doubling the cable over, so everything is off by a factor of two no matter what.

Thanks for getting me to do some research on this, its been a nice exercise.

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#128 [url]

Jun 6 11 10:05 PM

Not to mention that the value at double the cable length is meaningless from the trainee's perspective - pretty much everyone will stretch the cable to at least triple its resting length (16").

A long-armed individual will require much more strength to complete a pull than one with a shorter "wingspan". Even a difference of several inches will increase the resistance of the cable by quite a bit. So in truth the pullweights quoted, even if they were 100% correct, would be meaningless.

What Lifeline should have done is what gilstrap has already suggested - graded the cables from "beginner" through to "advanced" and maybe "elite" by color, not messed around with numbers in the first place.

I think the idea originated from their long TNT cables: they wanted to market them as an alternative to weights, so they said "a fully stretched cable A is the equivalent of a bicep curl with X lbs.", etc. This made sense with the 3-foot cables, as few people would stretch them far beyond double resting length. It does not work with 16" cables because pretty much everybody will stretch those to 3x or more resting length.

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#129 [url]

Jun 7 11 12:39 AM

Lifeline is now saying the ratings are for 3x pulls, but all the old text says either peak pull or 2x.


Yes, for so many reasons it would save all this if it were just a relative scale! 

The best way to do it would be to actually have a graph of pull strength vs pull length, but again, who's going to use it? And anyway the cables vary.

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#130 [url]

Jun 7 11 2:37 AM

the thing is the more you use lifline cables the more pointless the pull weights become ,,,,when im preparing a certain exercise i think right ill use 2 reds and an orange i dont think right ill set it up for 170 pound ....ill go as far to say that i dont know what any of the poundages are for any of the bands ....except that if you shift 3 blue bands on the expander your one strong "'@@@@ er .

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#131 [url]

Jun 7 11 5:32 AM

The graph makes no sense to me. The poundages are given for tubing stretched to 72''. The cables on the same page as the graph have a resting length of 60''

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#133 [url]

Jun 7 11 1:49 PM

MrBrady wrote:
You are correct Macky! I just dug out my old college physics book ( i kept it for situations just like this!)

I am guilty of overthinking the problem! The weight you measure with the scale is indeed the tension, and both hands will work that amount.

This does indeed mean that Lifelines method of measuring is way off for strand pulling., they are doing the equivalent of doubling the cable over, so everything is off by a factor of two no matter what.

Thanks for getting me to do some research on this, its been a nice exercise.
Well you done me a favour too, MrBrady.   I've been compelled to re-check my pullweight concepts.

I don't believe that anyone out of Lifeline's 30-odd staff are capable of accurately measuring one of their own Chest expander cables.  How could there be,  when they can't even tell the difference between their own 16" cables and their long cables.

Fatman and gilstrap are right.   Scrap the pullweights and stick to colours,  perhaps naming them, not numbering them.
Twice the resting length pullweight is irrelevant,  because nobody I know pulls out to just twice the resting length of cable.  Trouble is,  Lifeline can't even get a simple measurement like that right,  but help is on its way,  I've been hearing for the last 15 months or so. 
There's going to be some sort of dynamic calibrating gizmo installed that will solve all Lifeline's measuring problems.  Wonder if they thought about a $40 digital suitcase scale that would accurately measure all their gear in a single day ?

In the meantime,  Lifeline's pullweights on its chest expander page are not only meaningless, they are misleading and outright false.   

  

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#134 [url]

Jul 21 11 3:17 PM

Email Correspondence From Lifeline's Kevin Dorsey

Kevin Dorsey has given permission to share our email correspondence on this Forum,  regarding the issues of the advertised pullweights, and failures, of the Lifeline Chest Expander cables.

These are the most recent emails  :-

Sent: Thursday, July 14, 2011 1:35 PM   Subject: Update

 

Hey Neal, 
A brief update – the resistance band length on the chest expander issue you’ve raised is moving forward.  It looks probable that an additional 2-4 inches will be added to this product’s cables.  I’ll provide a confirmation when I have one, but wanted you to know progress is being made.
Thank you,

 

Kevin Dorsey


That's great Kevin,

I'm sure that with more careful quality control of batches,  that's going to stop what appears to be a chronic over-stretching problem with the Chest expander cables.

My suggestion would be to wait until Lifeline has this new length in production,  then after a new round of measuring the 9 strengths of Chest expander cables,  post up the correct pullweights on your Chest expander page.  There's no need to engage in complicated processes which only serve to confuse. Simply decide what expansion from resting length you want to determine the advertised pullweights for each cable colour.  Stop one end of the cable and pull out to required length with a simple scale. 10% margin is acceptable. Better still,  there is consensus on the Strand-pulling forum that pullweights are irrelevant because of differing arm-stretch lengths,  ( arm-stretch pullweight being the really important figure ), and should be done away with altogether,  with the colours being the sole indicator of cable strength.

Just an ask,  do you mind if I post up these emails between us on the Strand-pulling forum ?  I feel that there is a degree of cynicism amongst the strand-pulling community about Lifeline,  well deserved unfortunately,  which hopefully will be allayed by visual proof that something is being done about the Chest expander issues.

Best

20 July ........Hey Neal,

There are a few variable that we are looking at for cable snaps – the most likely culprit so far is off angle pulling.  When the cables are stretched so they come out of the cable pockets at unusual angles, the internal cable plug wears the inside of the tubing….  Most things aren’t as simple as they seem at face value.

We cannot, unfortunately, do away with our cable rating system as this is a keystone system we use to help our wide array of customers decide which bands are right for them.  In general, the system seems to work.  We sell well over a million bands a year, Chest Expanders being a small part, and the feedback is overwhelmingly positive.

I understand the frustration of those on the Strand-pulling forum, but as a company we do our very best to offer great value and information to help our customers navigate our product lines.  How would you help a new strand-puller decide which bands to start with?  I could potentially incorporate this feedback into a modification of our Chest Expander website product description.

As far as posting on the Strand-pulling forum, I have no problems with you relaying  information I share and appreciate you asking for permission.

As always, best regards.

 

Thanks for replying Kevin,
 
Regarding the cable snaps,  I agree that an awkward pulling angle may be one of the reasons for the snapping.  But one of my cables snapped in the middle without any warning,  and Forum members have reported differing quality of batches of cables they have bought.
 
If Lifeline is selling well over a million bands a year,  and Chest expanders being a small part,  then it follows that the bulk of the bands that Lifeline is selling are long bands,  not the short Chest expander bands.
I have repeatedly stressed that I am not talking about long bands,  whose pullweights may well be correctly advertised.
 
Your Chest expander cables advertised pullweights are 300% in excess of what they really are.  This is blatantly false advertising and I have repeatedly brought this plain and utterly simple fact to Lifeline's notice over the last 16-17 months.
How many times am I expected to bring this elementary piece of proven information to Lifeline's notice,  before it dawns on someone there out of your 30 or so staff that what I am saying is true.  And why has nobody there apparently got the time-management skills to organise one hour to test the truth of what I am saying ?
 
"How would you help a new strand-puller decide which bands to start with?  I could potentially incorporate this feedback into a modification of our Chest Expander website product description."
 
Very simple.  Post the rated pullweights for each colour as for Three cables,  NOT each cable.
 
Kind Regards
Neal McKenzie

Last Edited By: BigBruvOfEngIandUK Jul 21 11 6:15 PM. Edited 1 time.

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#135 [url]

Jul 21 11 3:30 PM

Re: Email Correspondence From Lifeline's Kevin Dorsey

Nice Job Macky. I hope there is some actual follow through.

I taught a strand pulling session with about 15 people a couple of weeks ago, using the Lifeline system. We had one brand new yellow snap. Seeing 15 people pulling at the same time, it really struck me that those poor bands are being overstretched.

The 'off angle argument' is certainly also a factor, but goes to show its also not the best design choice.

I will send my thoughts on to Kevin and Bobby as well.

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#136 [url]

Jul 22 11 6:24 AM

Re: Email Correspondence From Lifeline's Kevin Dorsey

To my mind,  Lifeline has its bit between its teeth with its multi-million dollar annual sales,  and doesn't seem to want to listen to anyone on the outside,  even if that someone is a customer and is acting in Lifeline's best interest as well as its customers,  rather preferring to listen to its "experts" who appear to only turn up every day to eat their lunch and pick their pay up.

If that seems harsh,  then why is it that the "engineers" and the CEO keep on ignoring two plain simple facts that have been proven by careful measurement by at least three persons,  and by experience with several customers,  that their advertised pullweights for their Chest expander cables are 300% exaggerated,  and that their batch quality of the same cables is erratic.  And why does it seem that the "engineers" are not capable of performing a calibration that three otherwise "non-engineers" are well capable of.   I've laid it all out in plain simple terms often enough.

Like all corporate-style companies who may well have one sincere representative out front who wants to remedy things,  but basically ignores well-meant warnings about its products,  nothing will probably happen until a few trainers lose their sight through being slapped in the face with inferior quality cables and decide to sue Lifeline for a few million.  It's only been a matter of good luck that this has not already happened.

Have you had any further response from Bobby,  MrBrady ?


 

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#137 [url]

Jul 22 11 6:11 PM

Re: Email Correspondence From Lifeline's Kevin Dorsey

I'll post when i do, i'm still formulating the message, will send it in the next day or so. The part pertinent to the cable snap will also go to Kevin.

I'll tell you having a cable snap in a classroom situation did not make me happy! Thankfully it was only an arm slap, but she said it stung. This is NOT GOOD! Remember its was an essentially new cable, and very well cared for. BUT it was one of the 'plasticy' ones. I'm not a suing kind of man, but if she had been injured......

My personal opinion, they should take the whole system back to the drawing board. Get rid of the clever but awkward connection system, and use loops that are a proven performer.

There was a small mix up in getting the sample of the Jungle Gym XT, so it only recently arrived at my door step. I can honestly say its a very well thought out product. If they can take the brains and profit that the XT has and put it into a next generation sheets expander they could have something great.

I think however that they are going to be too attached to their current system to realize it could be greatly improved.

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#139 [url]

Jul 23 11 5:01 AM

Re: Email Correspondence From Lifeline's Kevin Dorsey

I really think the handles are the main problem with the chest expanders , friction and awkward angles make them snap at the knuckle , you don't get the problem with the longer bands as most of the exercises are not as extreme in angle and are done in a more uniform manner .....i really think they need to go back to the drawing board with the way the bands are squeezed into the handles they need to develop some kind of a buffer which while keeping the bands stable protects them from the extreme of the handle until then id go as far to say as the lifeline expander is not fit for purpose in regards to heavy duty strand-pulling .....like i say i own a vast amount of lifeline equipment and think the tnt bands the power punch and the power pushup are fine ....but well there you go im waffling

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#140 [url]

Jul 23 11 5:16 AM

Re: Email Correspondence From Lifeline's Kevin Dorsey

ayeedee wrote:
It's best to make your own strandpulling equipment and cheaper too.

You have the most expensive of them all - the Samson!

Which looks really nice BTW!

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