What causes a crossbow string to break?

What causes a crossbow string to break?

Posted by Brad Patsy on Nov 14th 2019

It’s no secret that crossbows are becoming more and more popular with today’s archery hunters. Each year more states are making it legal to hunt with a crossbow during archery season. The great thing about crossbows is that a person can become very accurate with one, with little to no practice. Often times these will come sighted in from the factory, so the new owner can literally take a couple practice shots and be on the way to the woods. The bad side to this is that many crossbow owners are not familiar with the workings and sometimes get confused when something goes wrong, like a broken crossbow string.

Starting in July every year, not a day goes by that we don’t get a call from someone that has a crossbow with a broken string. When this happens, we always try to help them figure out what caused the string to break. Most of the time they just say the string was junk and they’ll never shoot that brand again, or something to that extent. The fact of the matter is that, unless it was grossly made incorrectly, a bowstring doesn’t just break. There is always something that caused the failure.

This article will shed some light on:

  • How to make crossbow strings last longer
  • What makes crossbow strings break

Age of Crossbow

The first and most obvious is age. With many crossbow shooters shooting less than 20 shots a year, it is often figured that the string will last many more years than the one on the compound bow they used to shoot. This is not the case though. Crossbow strings are under a much greater tension since most are in the 150 lb. pull range, versus 60-70 lbs. on a compound bow. It is a good rule of thumb to replace your crossbow string every other year and cables every other time.

Bolt Not Seated Tight Against the String

Probably the number 1 cause of crossbow string breakage is the bolt not being seated tight against the string. We see this one a lot. If the bolt isn’t tight, the string will jump over or under the bolt resulting in a dry fire effect. Many times when this happens,

  • The bow will be louder than normal
  • The bolt will only go a few feet
  • The fletching may be torn or damaged

Most of the time the string will break at one or both of the end loops.

Broken Nock or Bolt

Another issue that we see a lot of is a broken nock or bolt. Today's crossbows are super accurate and many times during practice you will pack several arrows in a tight group. This can be bad, as a nock or bolt gets damaged. With the force during the shot, a cracked nock or cracked bolt can let go, once again resulting in a dry fire type situation.

Incorrect Nocks

The use of incorrect nocks is another issue. Every brand/model of crossbow has a specified nock to be used. There are several styles, so it can be confusing. It’s always best to either check your owner’s manual or with the manufacturer to be certain the correct nocks are in your bolts.

Proper Care and Maintenance

It’s important that proper care and maintenance are executed with your crossbow strings. Crossbows are tougher on strings, compared to vertical bows; it’s just the nature of the beast. As a result, they require a little more TLC:

  • They need to be waxed more frequently
  • A good rail lube is a must

Just last week a customer bought a replacement string for his crossbow and sent a picture with a complaint that he had only shot 5 shots and the center serving was starting to unravel. I replied and asked what rail lube he was using. His reply was “What is rail lube?”

Improper Discharge

Something we don’t see a ton of but do get a couple horror stories about each season, is improper discharge. The best thing is to shoot a normal field tipped bolt into some sort of target. I’m not a big fan of discharge bolts, but some are better than others. What not to do is simply hold the crossbow at your side and fire into the ground. If the bolt hits the ground before it clears the string, there will be issues.

I hope this article has shed some light on how to make crossbow strings last longer and what makes them break.

Related articles:

Crossbow Hunting Tips


Choosing the Correct Crossbow String Material