How do I get thicker Biceps?

[TOkidd]

Concentration curls are great, but are a more targeted exercise for achieving bicep peak. IMO, not the best for building general mass and thickness.

[Chris303]

They say the Bicep has two parts? Inner and outward muscle group, My outward part is great but the inner seems to be lacking mass, making my arms looks smaller than they really are.

Wide arm curls?

[digsy1983]

My outward part is great but the inner seems to be lacking mass, making my arms looks smaller than they really are.
?

so you are after working the peak??? pretty boys on the cable machines are good for peak work and also partial reps on preacher curls (from the halway point to the close postion) i've found anything thing that the arm curls from semi - bent to fully bent is good for working peaks, and also ive found 8-12 rep max per set most beneficial.