To build big biceps, you need to add in some neutral-grip exercises. A neutral grip (thumbs up, palms facing one another) will hammer the brachialis, which sits underneath the bicep, adds thickness to the arm, and pushes the bicep up, making it appear bigger.

Exercises like a hammer curl or pinwheel curl (cross body hammer) with slower tempo work well.

Related:  Arm Training for Natural Lifters

Related:  The 10 Best Biceps Training Exercises