How To Restring A Crossbow: A Safe, Step-by-Step Guide For Compound And Recurve Models

Restring a crossbow safely by utilizing a specialized bowstringer for recurve models or an approved mechanical crossbow press to compress the limbs on compound models before swapping the string. To maintain peak velocity and prevent mechanical failure, ensure the replacement string matches manufacturer specifications, adjust twist rates to achieve the exact axle-to-axle (ATA) distance, and apply high-grade polymeric wax to all non-serving areas.

Replacing a worn-out crossbow string is one of the most critical maintenance tasks for any archer. Because modern crossbows operate under immense kinetic tension—often holding 150 to over 250 pounds of draw weight—understanding how to safely relieve limb pressure, swap strings, and align cams is paramount. Neglecting proper procedure not only risks destroying your equipment but also presents a severe physical safety hazard.

This technical guide details the processes for restringing both compound and recurve crossbows, aligning with archery industry standards to ensure your bow retains its speed, accuracy, and structural integrity.

Essential Gear, Safety Benchmarks, and Pre-Restringing Prep

Before beginning, you must identify whether you are working with a recurve crossbow or a compound crossbow. Recurve crossbows feature long, sweeping limbs and a single continuous string, allowing you to use a manual double-loop bowstringer. Compound crossbows feature a complex system of pulleys, cams, split or solid limbs, and a system of cables alongside the main string. Compound systems require a specialized mechanical bow press to safely compress the limbs. Under no circumstances should you attempt to press a compound crossbow using improvised ratchet straps or automotive tools.

Required Tools and Operational Benchmarks

• Essential Gear and Materials:

  
  
  
  • For Recurve Crossbows: A heavy-duty, adjustable recurve bowstringer (a cord with cup or loop ends that is longer than the actual bowstring).
  • For Compound Crossbows: A manufacturer-approved, heavy-duty compound crossbow press with split-limb or solid-limb adapters.
  • Replacement String & Cables: High-performance polymeric string (such as BCY D97 or Dyneema) matching your crossbow model's exact OEM specifications.
  • Maintenance Products: High-grade polymeric string wax (silicone or beeswax-based) and non-acidic rail lubricant.
  • Measuring Tools: A dial caliper or standard tape measure to verify the axle-to-axle (ATA) distance and brace height.
  • Safety Equipment: ANSI-approved safety glasses.

• Mandatory Prerequisite Knowledge:

  
  
  
  • Axle-to-Axle (ATA) Dimension: The precise distance between the center points of the limb axles, measured when the bow is uncocked.
  • Brace Height: The distance from the center of the string to the throat of the pistol grip or a designated riser mark (specifically for recurve models).
  • Twist Direction: The orientation of the string's twists (usually counter-clockwise or "Z" twist) to prevent the center serving from unraveling during cocking.

• Projected Project Benchmarks:

  
  
  
  • Estimated Budget: $35 to $75 for replacement strings; $150 to $400 for a specialized portable or bench-mounted crossbow press (or a modest fee at a local pro shop).
  • Estimated Duration: 30 to 45 minutes for recurve crossbows; 45 to 90 minutes for compound crossbows.

Comprehensive Step-by-Step Crossbow Restring Workflow

Step 1: Conduct a Comprehensive Pre-Service Inspection

Before introducing any new components, you must verify the structural integrity of the entire crossbow chassis. Examine the limbs under a bright light, searching for micro-fractures, splinters, or delamination. Wipe down the limbs with a dry microfiber cloth; if the cloth snags on the fiberglass, do not attempt to press or string the bow. Inspect the cams on compound models for hairline cracks, bent rims, or worn axle bearings. Compare your new replacement string with the old one to ensure the serving length, loop size, and overall length match.

Warning: Never attempt to compress or restring a crossbow with compromised, splintered, or cracked limbs. The immense stored energy can cause the limbs to shatter violently during compression, leading to catastrophic equipment failure and severe personal injury.

Step 2: Relieve Limb Tension

The method for relieving limb tension depends entirely on your crossbow's design. Follow the corresponding sub-steps below for your specific model type.

Method A: For Recurve Crossbows (Using a Bowstringer)

1. Slip the larger loop or cup of your auxiliary bowstringer over one limb tip, sliding it past the existing bowstring loop down onto the limb arm.
2. Secure the opposite loop or cup of the bowstringer firmly onto the outer tip of the second limb.
3. Step onto the middle of the auxiliary bowstringer cable with both feet flat on the ground, keeping your feet shoulder-width apart.
4. Pull up on the crossbow stock with steady, upward back pressure. This action compresses the limbs mechanically, causing the primary, worn bowstring to slacken completely.

Method B: For Compound Crossbows (Using a Mechanical Bow Press)

1. Adjust the fingers of your mechanical crossbow press to match the width and angle of your crossbow's limbs. If you have a split-limb compound crossbow, verify that you are utilizing approved split-limb adapters to prevent point-loading the limb tips.
2. Place the uncocked crossbow into the press. Ensure the press fingers contact the limbs only at the manufacturer's designated pressing points (usually directly adjacent to the cam housing).
3. Slowly turn the crank or actuate the hydraulic pump on the press. Watch the main string continuously as you compress the limbs.
4. Stop compressing the very instant the main string and cables go slack. Do not over-compress the limbs, as this can crush the fiberglass matrix or bend the axles.

Step 3: Remove the Worn String and Analyze Cable Routing

With the tension safely relieved, you can now remove the old components.

1. Slip the loops of the slackened string off the limb tips (for recurve models) or off the cam pegs (for compound models).
2. If you are servicing a compound crossbow, take a high-resolution photograph of the cam system, cable slide, and yoke routing before removing any parts. This photo will serve as your primary visual reference.
3. Slide the worn string completely out of the cable slide or barrel track.
4. If you are replacing the cables alongside the main string, remove them one at a time. This one-by-one replacement technique prevents you from losing track of how the cables cross in the cable slide and attach to the opposite tear-drops or axles.

Step 4: Adjust Twist Rates and Mount the New String

Modern synthetic bowstrings require twist adjustments to fine-tune their length and prevent the serving thread from separating under the friction of the trigger latch.

1. Lay the new string flat. Twist the string in the same direction as the serving wrap (typically counter-clockwise) to prevent the serving from separating when drawn.
2. Add twists to achieve the manufacturer's target length. As a general rule, adding 1 full twist per 2 inches of string length is an ideal starting baseline.
3. Fit the loops of the new string over the limb tips (recurve) or over the cam posts (compound). Ensure the loop sits flat on the post or groove without twisting on itself or riding up on the shoulder of the cam.
4. If you are working on a compound system, route the main string around the perimeter tracks of the cams, ensuring it sits perfectly within the CNC-machined grooves. Route the cables through the cable slide, verifying that they cross at the correct location to prevent cable-on-cable rubbing, which causes premature wear.

Pro-Tip: Adjusting the twist rate directly impacts your crossbow's timing and velocity. Adding twists shortens the string, which increases brace height and decreases axle-to-axle length. Removing twists lengthens the string, lowering the brace height. Always adjust twists evenly on both ends of the string to maintain symmetry.

Step 5: Decompress the Limbs and Verify Alignment

Slowly introducing tension back into the system requires focused attention to prevent the string from slipping out of its tracks.

1. Slowly back off the tension on your mechanical press (compound) or slowly lower the crossbow stock while stepping on the auxiliary bowstringer (recurve).
2. Stop every few turns to manually verify that the string loops remain perfectly centered in the limb grooves or cam tracks.
3. Ensure the cables are running straight through the cable slide and are not hung up on any metal edges of the riser or cams.
4. Once the limb tension is fully transferred back onto the new string, remove the bowstringer or lift the crossbow out of the mechanical press.
5. Measure the axle-to-axle (ATA) distance. Compare this measurement against your manufacturer’s specifications. If the ATA is too wide, you must re-press the bow and add more twists to the string and cables to shorten them. If it is too narrow, remove twists.

Step 6: Post-Installation Conditioning, Waxing, and Cam Synchronization

Before firing your first shot, the new string fibers must be conditioned and settled into place.

1. Apply a generous amount of high-grade silicone or beeswax-based string wax to the exposed, non-served fibers of the main string and cables. Do not apply wax to any portion of the string that is served (wrapped with protective thread), as this will attract abrasive dirt and degrade the trigger mechanism.
2. Rub the wax vigorously into the fibers using your thumb and index finger, or a small piece of leather. The heat generated by this friction melts the wax, allowing it to penetrate the core of the synthetic bundle.
3. Apply a thin, even layer of specialized rail lubricant to the barrel track where the string glides.
4. If working on a compound model, inspect the cam synchronization marks (usually small dots or lines etched into the cams). The limb edges should align identically with these marks on both sides. If they are out of sync, press the bow and add or remove twists to the individual cables until the cams rotate symmetrically.
5. Discharge 5 to 10 "settling shots" using a heavy, manufacturer-approved practice bolt into a high-density target block. This settles the knots, loops, and servings into their final structural orientation. Re-verify your ATA measurement after these initial shots and adjust twists if necessary.

Crossbow String Specifications, Twist Rates, and Maintenance Tolerances

The table below outlines the standard material properties, setup configurations, and maintenance schedules for modern crossbow string systems.

Diagnosing Restringing Failures and Cam Timing Adjustments

When restringing a high-tension crossbow, slight adjustments are often necessary to correct alignment issues. Use the diagnostics below to identify and resolve common post-installation issues.

• Issue: Cam Lean or Out-of-Sync Rotation

  
  
  
  • Root Cause: Unequal tension between the dual cables or asymmetrical twist rates in the yoke arms. This imbalance pulls one side of the cam out of vertical alignment, causing the string to track off-center.
  • Actionable Fix: Place the crossbow back into the mechanical press to compress the limbs. Locate the yoke cable on the side of the cam that is leaning. Add one to two twists to the yoke leg on the leaning side to draw the cam back into vertical alignment. Re-check the cam synchronization marks at rest and adjust the main cables until both cams rotate in perfect unison.

• Issue: Excessive Center Serving Wear Near the Latch

  
  
  
  • Root Cause: The trigger claws or anti-dry fire (ADF) latch mechanism has sharp burrs, or you applied string wax directly to the serving. Wax attracts grit, which acts like sandpaper inside the trigger box.
  • Actionable Fix: Use a fine-grit crocus cloth to polish the edges of the trigger claws to remove micro-burrs. Clean the trigger box using compressed air and a non-residue solvent. Never apply wax to the served center section of the string; use only dry-film lubricants or specialized rail lubes on the barrel track.

• Issue: Loss of Velocity or Decreased Brace Height

  
  
  
  • Root Cause: The new string has experienced initial fiber stretch (creep), causing the overall string length to increase and the axle-to-axle (ATA) distance to expand.
  • Actionable Fix: Press the crossbow to relax the limbs. Disconnect one loop of the main string and add three to five counter-clockwise twists to shorten the physical length of the string back to OEM specifications. Ensure you add an equal number of twists to both sides of the string to keep the center serving centered over the rail.

Frequently Asked Questions

How often should I restring my crossbow?

You should replace your crossbow string and cables every two years, or every 500 to 700 shots, whichever comes first. Synthetic fibers degrade over time from UV exposure and structural fatigue, even if the bow is stored in a case. Immediately replace your string if you notice broken strands beneath the serving, severe fraying, or separation of the serving thread.

Can I restring a compound crossbow without a press?

No, you must never attempt to restring a compound crossbow without an approved mechanical press. The limbs of a compound crossbow are under extreme pre-load tension; trying to remove the string or cables without a press can cause the limbs to violently release, splintering the fiberglass and causing serious injury. Portable inline presses or bench-mounted presses designed specifically for wide-riser crossbows are the only safe tools for this task.

What is the difference between string wax and rail lube?

String wax is a thick, tacky compound (often based on natural beeswax or silicone) formulated to penetrate and bind the loose, exposed strands of synthetic string material together, keeping moisture out. Rail lubricant is a thin, liquid, or dry-film lubricant designed to reduce friction between the center serving and the flight deck of the crossbow barrel. Mixing these up by applying sticky wax to the rail will drag down your arrow speed and gum up your trigger mechanism.

How do I know if my crossbow string is twisted in the correct direction?

Examine the direction of the serving thread wrapped around the center and ends of the string. You must twist the string in the same direction that the serving is wound. If you twist the string in the opposite direction, the serving thread will loosen, swell, and quickly unravel when subjected to the physical claw pressure of your crossbow's trigger latch.

Upgrade Your Crossbow Performance

Maintaining a fresh, professionally installed string system is the single best way to preserve your crossbow's pinpoint accuracy and high-velocity output. Equip your archery bench with premium-grade replacement strings, mechanical presses, and specialized lubricants to ensure your gear remains field-ready and safe season after season.