I'm currently trying to work towards building up the strength for getting my first pull up, using a doorway pull up bar like this one: https://www.amazon.co.uk/AETKFO-Strength-Adjustable-Equipment-Installation/dp/B0H3Z3D1MH.
I'm about 6'1 (184cm) tall and have wide shoulders & long arms, so when I go to full hanging extension my knees are just above the floor. I also find that my hands are right at the edges of the main bar (before the extending mechanism joins it) to get a comfortable shoulder width/just beyond grip. If I hang gym rings off it then for trying to do pull ups it lowers the height more and, whilst I've not tried it, I suspect my knees will sit on the floor. Due to an ongoing back/glute injury I can't really practice with my legs in front of me as it flares up my pain.
I can dead hang for about 15-20 secs and can do 3x8 scapula pulls. When I tried to do negatives or unassisted lock offs at the top position, I simply don't have any sort of strength to hold it yet. I've been playing around with different ways of trialling jack-knife pull ups but I have to be careful as the overall height results in my knee/distal quad which are supporting me flaring up an old injury around it due to the extreme flexion it requires. The best technique for jack-knife pull ups I've found so far is to use gym rings lowered down and to have my feet on the floor with knees bent, although the rings are still about three quarters of the way up the doorframe height due to my long arms.
I came across the JOROTO FoldableĀ pull up tower (which also allows for dips, incline rows and press ups) here: https://www.amazon.co.uk/dp/B0F7QXK79S. In one of the reviews I've watched, the user who is 5'11 had to bend his knees slightly but at my height and having measured the height, it would definitely give me about an extra 8" (20cm) of height over the doorway bar (even more over my rings) and more width for grip.
Would the tower offer any noticeable benefits for helping me work towards my goal of a pull up, or should I just concentrate on putting in the work with my current doorway bar (and assistance work with rings) and just accept that I have to bend my knees a lot
Thanks for any advice.
TLDR: Would I benefit from buying a pull up tower which would give me about 8" (20cm) of additional height to help a tall guy with long arms work towards his first pull up (and help alleviate a back/glute and a knee injury from laring up)?