Hi guys,
It seems to be a common misconception that a seat harness is good for a bad back. This may or may not be true depending upon the reason for the bad back.
I heard it said by a doctor that a seat harness allows the upper body to remain in constant compression and with the jarring and bent angle as you try and remain upright, that any compressional pain related injury like slipped disc, bulging disc, worn discs, pinched nerve etc is actually worsened by a seat.
A good Waist harness on the other hand allows the back to unload the compression and helps keep the back straight thus releiving some of the pain of compression and bending. You will bend at the hips rather than the lower back. This is true only of a good supportive waist harness like the wide and high back Flight Control by Flying Objects.
A narrow spreader bar although when setup on a wide tape running from one side to the other of the harness will slide around making it easier to ride switch and blind, it will also pull upwards and roll more digging into your ribs which can be augmented by using a spreader bar pad. However, add this to a narrow spreader bar also pulling the two tapes in on a trapezoidal angle will unecessarily pull inwards towards the spreader causing acute compression of the ribs which leads to a lot of pain and worse.
A Spreader bar is designed to spread the load to as wide as possible to prevent rib compression due to a narrow pulling angle created by a short spreader.
The one in the pictures above would be ideal but it looks big and cumbersome. Better to just ride a waist that will slide around your body as required. If your waist doesn't slide, wear a rashie under it and it will rotate nicely.
Good winds,