28 vs 29mm bar for Deadlifts

[TimK]

First meet next week, looked at the rules and they specify a 29mm bar. Looked at mystery bars at my gym today for the first time to try and figure out what they are and there was a very worn, barely legible "Capp Texas Power Bar" logo on the end. I looked this bar up and it's supposedly 28mm.

It's the only bar I've trained with. I've had grip issues in the past but I've been working on strengthening my grip and thought I had gotten to the point where it won't be a problem at the meet. Now I'm not so sure. Am I going to drop my deadlifts? Will I struggle to hold on to 315? Is seppuku my best option at this point?

[Les]

I don't think it will be that big of a difference. Isn't the Texas Power Bar 28.5mm? So it would be a half a millimeter difference. I went from 27mm to 29mm and pulled the same, but I have larger hands.

[TimK]

I don't think it will be that big of a difference. Isn't the Texas Power Bar 28.5mm? So it would be a half a millimeter difference. I went from 27mm to 29mm and pulled the same, but I have larger hands.

Hmm, now that I look again all the places list it as 28.5mm but the schematic diagram that they show (presumably from the manufacturer) shows 28mm: http://www.liftinglarge.com/Texas-Power-Bar

Oh well, I guess I'll find out if it makes a difference next Saturday. My hands are probably average size, not particularly small so hopefully the difference is negligible.

[simonrest]

I could notice a difference when going from the 28mm bars in my gym (cheap crappy junk bars) to the 29mm bar in competition, but it didn't really effect my lifts.

[d0uevenlift]

I could notice a difference when going from the 28mm bars in my gym (cheap crappy junk bars) to the 29mm bar in competition, but it didn't really effect my lifts.

I can tell the difference as soon as I grab the bar, too. But it doesn't affect my lifts, either. If it ever does, I just assume it's all in my head. I haven't pulled on a deadlift bar in 8-9 months now because the USAPL uses the stiff power bars.

[Cody]

If you are pulling conventional, of medium or greater height, and grip isn't a limiting factor for your pull, bar diameter makes zero difference to how much one can actually pull.

[DoctorWho]

I would have thought that 28 vs 29 of the same steel would make a difference. If the deflection is proportional to the moment of inertia (which I think it is), a 29mm bar should deflect about 15 percent more than a 28mm bar. So let's say I'm deadlifting 1,000 pounds. As I pull to take "slack" out of the bar at say 800 pounds, which is relatively easy for me, my hand positions are 15% higher on the 28mm bar than the 29mm bar, which I would have thought would be an advantage. So what accounts for the no-advantage-in-practice result?

[Cody]

I would have thought that 28 vs 29 of the same steel would make a difference. If the deflection is proportional to the moment of inertia (which I think it is), a 29mm bar should deflect about 15 percent more than a 28mm bar. So let's say I'm deadlifting 1,000 pounds. As I pull to take "slack" out of the bar at say 800 pounds, which is relatively easy for me, my hand positions are 15% higher on the 28mm bar than the 29mm bar, which I would have thought would be an advantage. So what accounts for the no-advantage-in-practice result?

Assuming your 15% figure is accurate here. But 15% increased deflection =/= 15% higher start position.

Let's say you're so strong that the 29mm bar deflects a full 1" when you pull... Using your 15%, that would mean it deflects 1.15" on a 28mm... That's a difference of 0.15" in ROM. That's the difference between wrestling shoes and deadlift slippers, i.e. none, really.

[damufunman]

I would have thought that 28 vs 29 of the same steel would make a difference. If the deflection is proportional to the moment of inertia (which I think it is), a 29mm bar should deflect about 15 percent more than a 28mm bar. So let's say I'm deadlifting 1,000 pounds. As I pull to take "slack" out of the bar at say 800 pounds, which is relatively easy for me, my hand positions are 15% higher on the 28mm bar than the 29mm bar, which I would have thought would be an advantage. So what accounts for the no-advantage-in-practice result?

Not 15% of the length of pull higher, but 15% of the deflection higher, which if memory serves, Manveer calculated about 1/16" of an inch difference or so.

Cody beat me to it.

[TimK]

This thread is about grip, not deflection!

[cwd]

This thread is about grip, not deflection!

In which case, 1mm more diameter is 3mm less overlap of your middle finger and thumb in a hook grip.

This would make no difference at all to me, as I have long enough fingers that I have overlap to spare on a B&R bar. Stubby-fingered folks might have a different experience.

[Hanley]

First meet next week, looked at the rules and they specify a 29mm bar. Looked at mystery bars at my gym today for the first time to try and figure out what they are and there was a very worn, barely legible "Capp Texas Power Bar" logo on the end. I looked this bar up and it's supposedly 28mm.

It's the only bar I've trained with. I've had grip issues in the past but I've been working on strengthening my grip and thought I had gotten to the point where it won't be a problem at the meet. Now I'm not so sure. Am I going to drop my deadlifts? Will I struggle to hold on to 315? Is seppuku my best option at this point?

Shouldn't make a difference, brah.

I've randomly interchanged Capp's TPB the and Ohio Power Bar throughout my pulling life.

[omaniphil]

It may make a difference depending on your grip style. I used to pull with a hook grip and I don't know if it was in my head, but I didn't have nearly as good a hook grip on the 29mm bar than I did on a 28mm bar. I also have relatively fat, stubby fingers, so that may have something to do with it. With mixed grip, no difference at all. I've even pulled on junky 32mm bars, and with mixed it feels fine.

[DoctorWho]

The deflection analysis seems right to me. I think I recall hearing that pulling the bar first to deflect the bar was a good practice. Is that for reasons other than deflecting the bar?

[Allentown]

The deflection analysis seems right to me. I think I recall hearing that pulling the bar first to deflect the bar was a good practice. Is that for reasons other than deflecting the bar?

At heavy weights the force necessary to deflect the bar is much lower than the force necessary to lift the weights. If you want to pull something with a rope, you don't start pulling a slack rope as hard as you can.

[DoctorWho]

The deflection analysis seems right to me. I think I recall hearing that pulling the bar first to deflect the bar was a good practice. Is that for reasons other than deflecting the bar?

At heavy weights the force necessary to deflect the bar is much lower than the force necessary to lift the weights. If you want to pull something with a rope, you don't start pulling a slack rope as hard as you can.

But the analogy would be to pulling a slightly elastic rope, and in that case you might start pulling the taught rope as hard as you can where for a moment some of the force goes into elongating the rope. And the elongation of the rope doesn't put you in better anatomical position for exerting force on the rope. No?

To clarify, when I got the advice to pull the bar first to deflect the bar, it might have meant pull slow enough to see the bar deflect before lift off?

[Allentown]

Think of the force curve for stretching the rope vs pulling the object. You can't apply 100% (or whatever realistic number) of your strength to stretching the rope, because it only takes 10%. Then you'd hit a sudden massive increase in the amount of force required.

[damufunman]

Think of the force curve for stretching the rope vs pulling the object. You can't apply 100% (or whatever realistic number) of your strength to stretching the rope, because it only takes 10%. Then you'd hit a sudden massive increase in the amount of force required.

Wouldn't this be a linear increase, assuming you're in the elastic region, ie not close to failure?
Force-Stretch curve

[Allentown]

Think of the force curve for stretching the rope vs pulling the object. You can't apply 100% (or whatever realistic number) of your strength to stretching the rope, because it only takes 10%. Then you'd hit a sudden massive increase in the amount of force required.

Wouldn't this be a linear increase, assuming you're in the elastic region, ie not close to failure?
Force-Stretch curve

It might. I have no idea. I'm making all that stuff up.

[TimK]

I pull mixed grip. I tried hook for a couple of weeks but if I remember correctly I couldn't make it work past 585. I'm going to just assume that this will be a non-issue, but if I can't hold on to my deadlift I'm blaming all of you people.