Most big-three guys – strength athletes who focus on the squat, bench, and deadlift – don't think they need bicep work. But having strong forearms and biceps will help the bench.
How? These muscles stabilize the elbow joint. Neglecting bicep work is a great way to end up with horrible elbow pain, which is a common occurrence, yet they seem to not know why. Hammer curls, done the right way, will prevent this.
Strict Hammer Curl
Now, these aren't the swinging-dick hammer curls you see a lot of guys do at the gym, where they use ultra-heavy dumbbells and get almost no tension on the biceps and brachialis.
Instead, do these with the dumbbells started on the front of your legs. This prevents cheating at the start of the movement, which means all of the tension gets hogged by the forearms, brachialis, and biceps.
To add some pain to it, do sets of 30 reps.