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Plate Thickness and Deadlifts

Usually when I deadlift I use rubber kg plates. A 25kg plate is probably about 2.5 inches thick. By the time you get to a max effort lift you may have a foot or more of weights on each end of the bar.

Someone mentioned to me the other day that if I were to use the metal plates my deadlift PR would go up. He said that since the plates are not as thick (25kg plate is .75 inch) they would be closer to the middle and easier to get off the ground. Is there any truth to this?

No. Thicker plates are easier because you don’t have to move the outside of the bar as far off the ground. Also, you can get the bar moving about an inch before the outer plates begin to move if the plates go out far.

johnytang24 would be correct.

Also the center of mass in either case would be the same along the length of the bar, if the bar deflects it might change a lil bit in the vertical direction.

[quote]johnnytang24 wrote:
No. Thicker plates are easier because you don’t have to move the outside of the bar as far off the ground. Also, you can get the bar moving about an inch before the outer plates begin to move if the plates go out far.[/quote]

Thanks for the fast reply, I thought it sounded too good to be true.

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Yeah, it does feel different. If you don’t have different sized plates, you can use 100lbs plates, since they’re thinner than 2 45’s. IT takes getting used to if you’re used to one and not the other. If you wanted to be really extreme, you could try putting the 100’s on, then putting them on as far out as possible (holding them there with clamps).

This is a good question. I pondered “density” of weights many years ago, but everyone I talked to thought I was nuts for asking. I personally ALWAYS lifted better with thick bumpers than with thin iron plates. I never knew why, but I would buy the theory about the plates far out not moving right away. Especially with a more flexible bar.
But it could be another factor. For instance, as a shot putter, we had an option to use a more dense, smaller shot put made out of copper rather than the usual iron. It seemed like a great idea, but NOBODY could throw it as far. Conversely, the indoor shot was 20% bigger than the regular shot, and people could throw the same distance, it didn’t negatively affect us.
What could this other factor be, then? Maybe force applied to a broader substance is slightly easier (for instance imagine lifting 400 lbs with an eight foot bar vs. a four foot one.) I’d take the eight. Maybe its a leverage factor.
Any engineers or physicists out there?
Doc

I remember when I was in high school repping 130 lbs (when I started out) w/ a 7’ bar. I put collars on the inside and gave myself about 8" of usable bar space. I loaded it up to 130 lbs and tried benching it. The 130 lbs felt like 170 lbs. There was a major difference in distance though. Not a couple of inches.

I think deadlifitng is a little different since you aren’t trying to stabilize a muscle that is pushing.

It also depends on the rigidity of the bar. I have an ivanko PLing bar and its WHIPPY! I am used to it since its all I use, but the greater the distance that the plates sit from the middle, the harder the bar is to control.

With a bar, you can’t apply more force due to placement of the plates on the bar. Thickness of the bar would affect your biomechcanical leverages (pushing or pulling with an open palm vs closed, the open is MUCh moredifficult), but not the placement of plates w/ such a small distance difference. There is a difference, such as rotational torque (a smaller change in the angle causes the bar to move further due to the increased overall distance of the longer bar), but nothing that would really stop you to the point where your max is 100 lbs less than a “normal” set up.

At least this is how it appears to me.

Dr.PowerClean i don’t have any complete answers concerning shot put but i would bet it has to do more with technique and practice then mechanical advantage. however i could see the problem with the small shot being that you need to have the shot pressed to your neck, with a smaller shot you would change the angle of your shoulder and upper arm and perhaps develop less force then if you had a larger shot, with the center of your hand farther from your neck. Imagine pressing with a variety of grips from narrow to wide.

As far as lifting, the distance of plates away from the center of the bar will effect the loading on the bar mostly when the bar is deflecting a large amount. otherwise the distance will effect rotational inertia which is basically how much force is required to get the bar off balance, and if it is off balance how much force is required to bring it back to balance. This would come into play more with pressing excersizes like Synthetickiller mentions in his high school experiment. Siince the weights were farther away from the center, if he got a lil off balance it took much more effort to restore the bar to balance and made the weight seem much more difficult.

Interesting discussion. i thought balance/stability was more the issue when pulling from the floor. The wider out with the plates means more effort needed to control the bar, while closer in would be easier? johnnytang is your scenario based on using a whippy bar?

Does anyone in this forum have access to a biomechanics lab, or an apparatus that measures and creates upward force? I would love to see an experiment done on this in a controlled environment.
If I try the method suggested by Push I think my results would be a little scewed. Since I am only interested in the 1RM aspect of this I would have to use heavy weight, and the second lift would feel heavier. If I used light weight both would easy and my RPE could be distorted.

[quote]robo1 wrote:
Interesting discussion. i thought balance/stability was more the issue when pulling from the floor. The wider out with the plates means more effort needed to control the bar, while closer in would be easier? johnnytang is your scenario based on using a whippy bar?[/quote]

Yes, the more the bar bends, the more noticable it is. If you’re deadlifting 135lbs on a squat bar, you probably won’t notice any difference. If you try with an olympic bar or deadlift bar with more weight, you’ll see.

I don’t think side-to-side balance/stability is much of an issue for most people. I’ve never seen anyone miss a deadlift due to stumbling to the side (unless their grip gave out)

[quote]2thepain wrote:
Does anyone in this forum have access to a biomechanics lab, or an apparatus that measures and creates upward force? I would love to see an experiment done on this in a controlled environment.
If I try the method suggested by Push I think my results would be a little scewed. Since I am only interested in the 1RM aspect of this I would have to use heavy weight, and the second lift would feel heavier. If I used light weight both would easy and my RPE could be distorted.[/quote]

i don’t know why you’d need a lab, you could easily calculate the deflection vs force or whatever you want to know

[quote]dom wrote:
2thepain wrote:
Does anyone in this forum have access to a biomechanics lab, or an apparatus that measures and creates upward force? I would love to see an experiment done on this in a controlled environment.
If I try the method suggested by Push I think my results would be a little scewed. Since I am only interested in the 1RM aspect of this I would have to use heavy weight, and the second lift would feel heavier. If I used light weight both would easy and my RPE could be distorted.

i don’t know why you’d need a lab, you could easily calculate the deflection vs force or whatever you want to know
[/quote]

Well then you could easily answer our question? Please tell me what would require more force to pick up, 600lbs which covers a foot of ground space on both sides of an 8 ft bar or 600lbs that takes up 6 inches of ground space on both sides of an 8 ft bar. Lets just say the deflection is 4 inches in both cases. I’m not being a smart ass, I didn’t do too well in Physics, and you appear to know the answer.

the force is going to be the same in either case… the only difference is how much the bar deflects before the weight comes off the ground. the center of mass for the thicker plates will be more towards the sides, so it will cause the bar to deflect more. The more deflection there is, the harder the lift will seem.

I can try to re-elaborate or explain if that made no sense haha

So what’s the answer, in terms of physics?
Should it be easier to deadlift 585 lbs if the bar is FULL on both sides than to deadlift 585 lbs when it has 6 narrow plates on each side?

I see. So a fully loaded 585 lbs bar will seem harder than a bar loaded with 6 narrow 45 lbs on each side?
And if, say, there had been a very narrow, but dense 270 lbs plate on each side, the deadlift of 585 lbs will be easiest in this case?

Dude, this is a 10 year old thread. None of these guys post here anymore.

I got an email about this, LOL. Posting a decade later is weird man…

To a degree, the wider the plates, the slower they break off the ground. So if you use calibrated competition plates, the plates break off the ground more quickly (harder). Wider break off the ground kind of every couple of plates, so it’s easier. This is assuming you have a whippy bar or a deadlift bar.

Keep in mind that this applies to really heavy deadlifts. You might notice it a little on 585, but it’s much more obvious closer to 700…

Lol, my bad. The reason I posted HERE is because it’s probably the only thread on the internet that directly addresses the question. Yes, I should’ve probably started a new thread.

Okay, so the thicker the plates and the more area that the weight is distributed across, the easier it is? Because I thought the poster I replied to stated that the thicker the plates, the closer the centre of mass is to the sides of the barbell, the harder the lift is.