How do you know when it is time for a new string on your bow ?

You don't really know.It's hard to say just by looking.I'd say if you have to ask and the bow is more than a year old then it's time. Especially if it's the factory string. Most factory strings are not made with the same care as a good after-market set.

Now I'll suggest a string maker right here on this site. Goes by the name of Gibblet. Very good quality, very reasonable price. The price is about the same as you'd pay for some generic strings hanging on the wall at your local shop.

Keep em waxed and replace about every two years. It's kinda like life insurance. You buy it never knowing when you're gonna die, but ya keep doin it.

If it's broke then it's time for a new string. Seriously, BG gave you good advise. I make my own and change them every year. Right now at the shop we get a ton of guys who open their bow cases for the first time since last hunting season and the strings are broken.

yea we get the saaame thing

A string should be dark and moist. You'll know when it's drying out because it'll turn white'ish and fray. If you keep the string waxed it will certainly last a couple years, I used to recommend that you replace the string every year, today I don't believe that's necessary, not a bad idea, but perhaps not necessary. Watch your string for wear, fraying and "weak" spots. Now if internal strings start to break, you many not notice it unless it's suddenly out of tune. The string could be creeping (rubber bands stretch). Measure your axle to axle and compare it to the factory ATA for the bow. A way off measurement might tell you the string creeped. (permanate elongation)

I'm not condoning this practice, but I've had the same string on my bow for three years and like Rob said, if you keep it waxed properly and often enough, itgreatly increases the life of the string.