Pssst. The pound rating on your barbell is mostly fantasy... the tensile strength is SCIENCE

Barbell deflection at a factory

Photo from a barbell factory. That's a prototype Vaughn barbell shaft being deflected with 1026kg (2262lb) of force.

How barbells get their strength ratings

There are two main measures of strength for barbells in the market today: The rule of thumb:

Quality barbells are going to give you a PSI strength rating for the bar, and cheaper/cruddier barbells are going to give you a pound capacity.

How to rate a barbell for pound capacity:
  1. Take a barbell
  2. Put it on a rack
  3. Load weight on the sleeves
  4. Take the weight off
  5. Is the barbell permanently bent? If yes, you done screwed up. If no, congratulations! That's a weight rating you can claim on the barbell!
Does this sound scientific?

Maybe for medieval England. Of course, we love Game of Thrones as much as the next person, but as a barbell rating methodology, there's a little too much magical thinking for our barbells.

There are three main failures with this style of rating:
  • Generally, only one sample is tested- only if it fails is another sample tested... also leading to the possibility of numerous tests until a positive is recorded, and used for marketing
  • The test in no way reflects real-world usage- people use barbells dynamically, not just loading them in a rack, then unloading them
  • Most companies don't even really do the test, they just guess or estimate a weight rating!
How to rate a barbell for tensile strength
  1. Buy quality steel from a trusted steel mill that has a tensile strength rating already tested and verified
  2. Heat treat (improves strength) and otherwise fabricate your barbell
  3. Test samples for tensile strength (this involves destroying the samples in the test, as the test is necessarily destructive)
This is what we do for all our barbells. It costs more, but the advantages are clear:
  • Consistent quality from production run to production run
  • A better understanding of the stress our barbells as designed to withstand
  • Stronger barbells

If "pound rating" is so bad, why is it so prevalent?

It's easy to do, and easy for people to intuitively understand.

If a person looks at a "1000 pound" barbell, they think they know what that means- they can load 1000 pounds on there, right? But since only a few people in the world (ever) could lift that much, a person would never need a stronger bar, right?

Of course, all the above is wrong. A "1000 pound" rating on a barbell is pretty worthless.

However, tensile strength ratings can be complicated, subject to fudging, and difficult to understand.

Continued next week with: what does PSI really mean? Including tensile and yield strength.

If you've enjoyed this, buy one of our (tensile strength rated) barbells maybe?

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