Awhile back, I wrote a blog post about this staircase by interior designer Thom Filicia, using a rope as a handrail (loved the idea then, still love the idea now). I came across a website that manufactures ropes for handrails (and their line even includes the details such as fittings, knots, and towel bars). The company is called Stair Ropes and they are based in the UK, with customers here in the States too.
They carry ropes in different colors and two-toned versions.
And different fittings and finishes.
And various types of knots and sizes.
Accessories too, like this towel ring.
I love the idea for an outdoor space too.