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I have a pull bar. It is 48 inches in-width and spans out 32 inches with the "pullup" portion of the bar located 30 inches into the spanned out end portion.

I would like to know how deep should I make the post hole. How wide? Should I use rebar? I would like the 4x4 to be 48 inches apart and 7.5 feet above ground. I would like to keep the post deflection at a minimum (if none at all). The pullup bar will be used by someone who is 300lbs so the post must be able to withstand the force of 300lbs muscle up and clap pullups (basically a 300lb man hanging from it and swinging) (the pullup bar is capable, the only questions are the post)

My plan was to make each post hole (2 post) 15 inch diameter by 48 inch deep, and on the 4x4 in-ground portion drill out some holes to friction place some rebar through the post so that it protrudes on each side a few inches in a attempt to help the concrete bond to the post better and better "stabilize" the post.

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    Your plans sounds solid, I would over-engineer it and go with 6x6 posts.
    – JD74
    Commented Apr 18, 2023 at 1:20
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    Where are you located and what type of soil/ground will you be digging into?
    – UnhandledExcepSean
    Commented Apr 18, 2023 at 1:36
  • @UnhandledExcepSean Southern California and the soil is regular loam.
    – FlexBendDeflect
    Commented Apr 18, 2023 at 3:44
  • @JD74 I need to keep the dimension 3.5 inch width for other purposes so for that reason If I do move up it will be a 4x6 which I am not opposed to either and might be the better fit however I also don't need this to last 20 years my main concerns are post deflections.
    – FlexBendDeflect
    Commented Apr 18, 2023 at 3:48
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    You might think that fence post discussions are not relevant to something designed to carry human weight, but wind force can be at least as great as anything you're likely to impart. I'd follow the same rules.
    – isherwood
    Commented Apr 18, 2023 at 13:29

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Since you've eliminated 6"x6"s as an option and you are concerned about deflection of the posts, my suggestion is to use 4"x6"x12' posts. The 4" face should be oriented towards the pullup bar. The rest of your plan sounds very robust for installation.

The depth of the install you suggested was 48" which is very deep, but the deflection isn't based on the depth of the beam into the ground. The entire thing overturning is the reason to burial depth when you have a 0" frost depth area like southern California. Loam soil doesn't pack very well, so a 48" depth in a 15" wide hole filled with concrete will work very well.

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  • I accepted you response as the answer.
    – FlexBendDeflect
    Commented Apr 23, 2023 at 0:35

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