Biceps strength can be greatly increased with any pull-up & chin-up workout when you are a beginner. Problem is, the better you get at pull-ups, the more you learn to engage your back – pull with the lats or armpit muscles. This is great because you will develop a great looking v-shaped body. However your biceps strength will reach a plateau because your arms will get less and less stimulation.
One solution is to start heavily relying on direct arm training with barbell and dumbbell curls. Although this is a great approach, there is yet another way to train with a compound exercise for greater biceps strength. Compound moves allow for a more natural loading of the muscles.
Here is a video we shot in the backyard of a nearby school of the mix grip chin-up. Notice how I am leaning towards the under grip arm and trying to pull with this side of my back. Don’t just pull yourself up. Instead use the muscles of the under grip side of the body.