Will the training aid rub my horse?

In our experience of over two years of use on many different horses, no horses have been rubbed. The rope was chosen, as it is high strength yet very soft and light. When fitted and used according to the instructions, the aids are never tight, or used for long periods. Our motto is 'if it's tight; it's too tight'. The hind piece is not much more than a fillet string and as it is used for short periods only, no issues have been found.