I don't get to leather work very often so I buy Marlowe's whipping yarn in small spools like an old fashioned 8mm movie spool, the no 2 thread size on that spool is 92 metres (302ft) from a local ships Chandler.
It comes in white, red blue, black and yellow and various thicknesses, it is waxed polyester. I have never had a fraying problem with it in 30 odd years on bike saddle bags, western sadddles and a whole lot more.
I have been toying with the idea of trying some of the braided fishing lines to see how they perform, one of the toughest for fishing is Dyneema which is designed to lay flat on the spool.It goes up to 150lbs breaking strain or more, I can tell you it is impossible to snap with bare hands and I am no weakling.
