Have you ever done traditional bicep work and felt most of the stress in your deltoids? This is more common than you think-especially if you have larger than average shoulders. The solution? Drag Curls, which were popularized by the late Vince Gironda. Drag Curls are one of those "lost exercises" which are almost never seen in modern times, but they pay big dividends.
You'll be using a light barbell. Don't worry—your muscles have no idea how much weight is on the bar. I would start with the 45lb bar (or lighter if you haven't been training long).
Begin the movement in a normal curl stance: bar at your thighs with your grip about shoulder-width or even slightly wider-this will vary from one person to the next. During this exercise you'll bend slightly at the waist, unlike normal barbell curls
Now, here's where it gets tricky. Instead of curling the weight up in an arch away from the body, as in a normal curl, DRAG the barbell up, keeping your elbows back at all times. Keep the bar in contact with your body throughout the curl. You'll drag the bar up to about mid-chest level (or a little higher if you can) pause, hold the top position for 1-2 seconds and then slowly lower it back down to your thighs Concentrate on flexing your biceps the entire time.
After about 4-5 reps you'll really feel this in the belly of your bicep and you won't feel it in your delts. Just feel your way around the movement and you'll find the groove that suits you best. Give this movement a shot.