Heavy BB curls (cheating with a slight knee jerk and body English..avoid doing curl grip cleans). After a few sets of cheating curls, add about 20 lbs ,or so, and do halfway up rep partials..controlling them all the way. Than follow with a couple sets of curls starting from the top position and lower half way down and than back up again.... controlling them all the way. Use a straight bar if you can, for all sets. This is a version of the old 21's (or 7's..7X3=21). Only difference is that there is no stopping with the original 21's; full 7 reps, than half way up 7 reps and finally 7 rep to the half way down position. With the first mentioned way of doing it, with a 60-90 rest between sets/exercises, a much heavier weight is used. That's what we are looking for. Why 7 reps each set?....I do not have a clue. Thickness/width should be the outcome for the biceps.
Can do reverse BB curls rather than regular curls if you wish for a whole different feel to the bicep development. In any regard, this version of 21's will be the only bicep exercise needed, if worked hard enough each workout. Good luck.
