When I first started working out I often did three to four sets of standing barbell curl pyramids as part of my regular bicep routine. 8 times 20s to 15s to 10s to 5s with no rest. After a while a friend of mine, who seems fairly knowlegable, told me that I should really only do pyramids once as the last bicep exercise I did. I soon scrapped pyramids all together and moved to preacher curls, concentration curls, and hammer curls. Now I want to switch it up (I've hit a plateau and need a new routine) and also in the process start defining my biceps (high reps low weight). So I was wondering if in fact pyramids would be a good start to do this, since you are lifting high reps. Any thoughts?