Most multi-joint upper-body pulling exercises predominantly train the biceps in the mid to shortened-range position.
To increase your strength, do exercises like preacher curls and what I call "face-away cable curls" shown here.
related posts
The Land of Giants
A behind the scenes look at the world of the strongman
Tip: 200 Reps for a Complete Upper Body
Superset these two exercises to build your back, chest, and arms. It's actually a pretty fun and challenging workout!
Tip: Here's Why You Have Puny Shoulders
Everyone thinks they know how to train delts, but very few have mountains under their T-shirts. Here's what they're missing.
Demolish Your Bench Plateau
Has your bench been stuck so long you've considered loading up the bar to your usual weight and just welding the damn plates on? If that's true, it's time to bust through that pesky plateau.