the rack i have is seat post rack so it dont have struts.id prefare to keep my rack. so how do keep the paniers out of spokes with this rack?.right now i amuseing paracord to make like a v from the rack to lower part of bike frame

Panniers with a very stiff backing that curves slightly away from the wheel at the bottom of the panniers helps a lot. But I have had problems even with racks that just have two struts, particularly if I mount the panniers far back on the rack to help prevent heel strike. For this reason, I try to only use racks with three struts.

i am trying to use the paracord as struts kinda works ok .havent tryied it fully loaded yet

Windchaser

A bit of caution would be called for . I can see a temptation to make the cord "nice and tight".
Consider very carefully that ANY tension on the paracord from the rack down to the lower frame is in effect PRELOADING the seatpost rack by however many pounds/kilos pressure you pull on the cord MAGNIFIED by the lever arm length of the rack. Most of the paracord i'm familiar with is rated between 50 to 150 lbs. strength. Whereas most seatpost racks have load limits of 15 to 25 lbs.

TIGHTENING the PARACORD is the SAME as PUSHING down on the RACK. Reducing the amount of weight the rack can carry.

Seat post mounted racks don't have the load capacity to take regular panniers. Some models have half frames that are intended to be used with top mounted rear rack bags with expandable cargo pockets. Anything
more than that and you should be looking at a different rack.

Well made panniers have quick-release, locking hooks that hold the pannier firmly onto the rack, and a stiff board within the pannier to hold it's shape and prevent it drifting into the spokes.
Cheap panniers have poor fitting systems and lightweight materials that are prone to spoke contact. The best solution for these panniers is a rack with a dogleg strut.

I use a seat post rack and made 2 short bungee cords that attach to the 2 hooks on the panniers and onto my lower seat stay frame. I don't preload them very much but its just enough to hold the panniers in place. It works great. I made the bungee cords out of those color coordinated ones that would match my bike and just cut off all the extra after adjusting them to length. They ended up being quite short about 6in long ea.

I have Arkel and Ortlieb panniers and you can get even them in the spokes if you don't have rack struts positioned properly to keep them off the wheel.

Fabricate the stabilizing strut loops you are missing. you should be able to find wood dowel
if not aluminum rod. or folded sheet aluminum..


DIY , its not a computer app.

or stick with a rack top bag.. or get the beam rack with the struts, sell the one without.