I have a question in regards to strings and pulleys. The Winch and pulley kit comes with 4 feet of thread; is there a limit to the length of a strand of thread like there is for pneumatic tubing? I need to have 2 loops of string that go for about 15 feet each, so 4 feet is just a bit short for the two sides.
I don’t believe there is a limit… I’ve used and seen robots in the past which used more than 4 feet of string compete. Don’t take my word completely though.
This was asked in the Official Q+A not long ago.
https://vexforum.com/t/answered-rope-length/26588/1
Karthik says you are allowed string in unlimited amounts, so two 15’ lengths should be legal.
I know the rule states:
<R7> Robots are allowed the following additional “non-VEX” components:
j. An Unlimited amount of 1/8", braided, nylon rope.
I hope that’s the rule word for word more or less, but look it up. So you can just use identical bet longer nylon string to the stuff you have. I hope this helps. 
Well looks Welshkiwi beat me to answering the question by a minute or two minutes. I still hoped I helped in some way…
Glad I didn’t answer wrongly. Sweet.