Are there certain anatomical characteristics (or whatever characteristics) of a lifter that might mean they don’t lift more weight with a deadlift bar? I pull only conventional and I’ve pulled 551 on a texas deadlift bar with competition kilo plates but also pulled over 500 on a 29mm stiff ass rogue power bar a couple of times (502, 529 also with competition kilo plates) with no loss of bar speed or increase in RPE as compared to those same weights on a deadlift bar. In fact the 502 I did on the rogue power bar may have been the fastest 500 pound deadlift I’ve ever had. All lifts were done within a few weeks of each other and there was no obvious reason to think I’d be much stronger on any of the days in question. The lifts were performed at 5’10.5" 180-185 pounds body weight. I pull with a rounded back (mostly upper, but a little lower back rounding also) but somehow absolutely never have lockout issues. On circa max attempts the weight is very slow off the floor and stays at that same slow speed without any deceleration all the way to lockout. I’ve literally never missed a weight I got off the floor unless my grip failed and I do not hitch or ramp which isn’t what I’d expect from a rounded back deadlifter. I even take a fairly narrow heels close stance.
You got 20lbs out of a deadlift bar if I’m reading this correctly, which would suggest you did, in fact, lift more weight with it.
That said, if you haven’t trained with one before I wouldn’t expect that maximum improvement in potential performance by using one.
Well, I didn’t max out at 529 on the stiff bar, that’s just where I stopped adding weight. On that particular day I feel like I could have pulled 550 at the same speed as on the deadlift bar if I’d tried. But I had been practicing on the deadlift bar for months by that time. If anything I was out of practice on the stiff bar.