Pull up is the best bodyweight exercise you can do for your back but they can also be used to develop the arms. For this purpose you need many variations.
Versatility is the key element for producing great and well-rounded results. If you stick to just one exercise variation, you can expect to cause muscle imbalances in the long run.
All pull up variations are great and you should utilize as many different ones in your training as possible. Although many pull up variations work the same muscles, the emphasis can be completely different.
Wide grip pull up will work the biceps but the stimulus is not much and the range of motion is quite small. You will develop the biceps to a small degree, but far from their full potential.
Moreover, the articulations of the body can be very different in pull up variations:
- Basic chin up includes dominantly the shoulder extension (mostly lats)
- Wide grip pull up incorporates the shoulder adduction (emphasis dominantly on teres major).
- If you arch your back and keep the body more horizontal, you will be utilizing more of your posterior deltoids.
- Keeping the lower back flat (hollow body) will instead let you use more of your lats.
It's a mistake to think one pull up variation is better than another. They are all effective and all necessary to ensure the structural balance of the body. This is the reason why In Movement 20XX there is a wide range of different pulling strength progressions paired with back mobility drills.
Another mistake is to use bad form and too much weight. Quality of the form should always be the number one. It's not how many repetitions you can do, but how well you do the repetitions.
Doing weighted pull ups is rarely necessary and can interfere badly with the form. They are great to do in order to shake things up and test the levels of strength though.
By working on these 4 pull up variations (preferably more), you will make sure your arms will grow strong and balanced. For perfect arm mobility bicep curls are needed, but you can get far by sticking to these exercises alone.