The old Turks write that there is 120 ways to string a bow. Ottoman bows are strung the safest with a device called ''kemend''. This is especially important for high poundage, extremely reflex and delicate bows.
Otherwise if these bows are strung normally e.g. with the step through method, the bow arms might turn and twist and might destroy the bow or hurt you. Because with this system the leg muscles are used, every bow can be strung. In this video I string and unstring my 110 lbs Kassai Hungarian bow:
I used a band which the bed/couch makers use. For my second kemend (the orange one) I used an industry band to pull heavy loads. The latter is 5cm wide and 240cm long. The reason for the width is firstly durability but secondly so it will not hurt your back.
Another way, if you dont have a sewing machine (nor the patience) you can make a kemend in a very easy way. Just make a know at each end of the band. This method has another advantage, you may not find your optimal length immediately, if there is a knot you can open it and adjust it easily.
Stringing the bow with your kemend
You put the kemend around your back as if a belt and cross the two ends in front of you. You prepare the bow in front of you. You place the string loop in one of the bow nocks. Then you place the small loop of the kemend into the same nock and place the big kemend loop in the other nock. In a sitting position you place both feet on each side next to the bow grip. Now you hold the 'bash' section of the bow with your hands and start pushing gently with your legs. During this movement it is very important to control the bow with your hands/feet so it doesnt turn and twist. After a certain point when you think you pulled enough to string the bow you let your hands go. You guide the string through the big kemend loop and place the string on the nock. The length of the kemend has to fit you exactly. When you stretch your legs you just have to have enough room to string the bow. When you want to unstring the bow you do all the steps again but backwards, so first push the bow with your legs and hold with the kemend so that you can unstring it. Then hold again with your hands and gently go back with your legs.
The loops of my orange kemend are big, of course they dont fit the nocks but it is very handy also with this type. Instead of the nocks, you place the kemend loops between the kasan and the bash sections and string the bow the same way.
A small but important tip: while you are sitting, wrap the kemend low rather than placing it at belt height. This way you can use the forces better and the kemend will not hurt your back.