Here's what you should do to avoid neck bending
1. Adjust the Truss Rod: Adjusting the truss rod is crucial when changing string gauges. The truss rod helps to counteract the tension of the strings on the neck. If you install thicker strings, you'll need to tighten the truss rod to provide more relief (bend) in the neck, counteracting the increased pull of the thicker strings.
2. Check the Neck Relief : Ensure that the neck has a slight forward bow (relief) when viewed from the side. This allows the strings to vibrate freely without buzzing against the frets. Use a straightedge or capo to check the relief and adjust the truss rod as needed.
3. Adjust the Bridge Saddles: Raising the bridge saddles can compensate for the increased string height caused by thicker strings. Adjust the saddles so that the strings are at the proper height above the frets, ensuring good intonation and playability.
4. Consider lighter spring in Tremolo Bridge : If your Stratocaster has a tremolo bridge, installing lighter bridge springs may be necessary to balance the increased string tension and prevent the bridge from sinking.
Remember to make adjustments gradually and slowly and tune the guitar between adjustments. If you are uncomfortable making neck adjustments yourself, consulting a qualified luthier or guitar technician is recommended to ensure your instrument is properly set up for the desired string gauge.