Bumper plates vs iron plates

[TommyGun]

I like it Andrew but how from a structural point of view are you going to compare deformation between different bars at different loading(say 135 through maybe 585? There is so much to tackle on this topic it wil be difficult capturing it all. My hope with the article is that it can conclude that different bars have different deformation characteristics, probably not significant until 400? 500? pounds. Not sure if we can run a simulation or to calculate manually of the deformation at the top of the deadlift using a standard grip width.
It would be harder but interesting to somehow bring the ‘whip” into it: the acceleration off of the platform and what that does to the bar. Gravity is the big thing here not just the metallurgy.

I salute you Andrew.

[Bill Hannon]

I like it Andrew but how from a structural point of view are you going to compare deformation between different bars at different loading(say 135 through maybe 585? There is so much to tackle on this topic it wil be difficult capturing it all. My hope with the article is that it can conclude that different bars have different deformation characteristics, probably not significant until 400? 500? pounds. Not sure if we can run a simulation or to calculate manually of the deformation at the top of the deadlift using a standard grip width.
It would be harder but interesting to somehow bring the ‘whip” into it: the acceleration off of the platform and what that does to the bar. Gravity is the big thing here not just the metallurgy.

I salute you Andrew.

The bar deflection calculation at the top of the DL is actually pretty simple - the bar acts like a simply supported beam with weight distributions on both ends. The main variable of concern is diameter, and how the knurl impacts the MoI would need to be looked at as well.

Whip is definitely more complicated. Hardness/microstructure plays into the damping coefficient, but you'd need to know the exact material and heat treat spec for a given bar to infer anything worthwhile - other than just a general statement between two physically identical bars of the same material - Bar A with heat treat XYZ will have more whip than Bar B with no heat treatment.

[Mark Rippetoe]

Maybe Bill would like to help Andrew with this article.

[AndrewLewis]

Maybe Bill would like to help Andrew with this article.

I would appreciate someone with knowledge of the manufacturing considerations.

I like it Andrew but how from a structural point of view are you going to compare deformation between different bars at different loading(say 135 through maybe 585? There is so much to tackle on this topic it wil be difficult capturing it all. My hope with the article is that it can conclude that different bars have different deformation characteristics, probably not significant until 400? 500? pounds. Not sure if we can run a simulation or to calculate manually of the deformation at the top of the deadlift using a standard grip width.
It would be harder but interesting to somehow bring the ‘whip” into it: the acceleration off of the platform and what that does to the bar. Gravity is the big thing here not just the metallurgy.

I salute you Andrew.

The article is going to start conceptual and generalized and move into the specifics pertaining to barbells.

Once the foundation is formed, applying it to barbells is pretty straight forward.

[MiguelTheNewbie]

FWIW, when I was outfitting my garage rack, I ended up going to a Big 5 that was going out of business and was clearing out floor stock. They sold me 400 pounds of cast iron plates for $150.

When I was in the back loading the plates into my truck, there were a pile of bars stacked in the corner. The employee helping me said that they would be throw away and if I wanted one I could take one, so I test rolled all of them on the concrete floor and took the straightest one. It was pretty crappy, it was plated with zinc, and the ends didn't even spin that well. I measured it at 32.4mm (!!) in diameter with my calipers, and it isn't even round (there's a flat that runs the length of the shaft.

However it's incredibly stiff: it's a great deadlifting bar because it doesn't budge at all, and being thicker it's more comfortable in my hands. When pulled from the floor it flexes very little. I don't use it for anything else. It's far stiffer than even my Rogue Ohio Power Bar (which is 29mm, and listed as 'No Whip') which I use for all the other lifts. So indeed it would seem that bar diameter is the main factor in 'whip'.

I would be very interested in reading the article when it's completed.

[AndrewLewis]

The whip observed is essentially bending compounded with bending at the correct time, so the same factors that affect the elastic deformation (bend) are going to have an influence on the whip.

[David Kirkham]

I would appreciate someone with knowledge of the manufacturing considerations.

Did someone just ring my doorbell?

[AndrewLewis]

Did someone just ring my doorbell?

I sent you a friend request.

[David Kirkham]

I have written this very article some time ago—Rip and I spoke quite a bit about it at the time. The article is in the rough stages but life got in the way (long story).

Anyway, I’d LOVE to help out. I have pretty extensive knowledge of manufacturing but ALWAYS love to geek out on materials science theory. I’ll find the draft and send it out to whoever for comment, complaints, eye-rolls, whatever. Rip is right, this is a sorely needed article for our community. The level of BS on bars is astounding.

Damn I love making stuff.