My Biceps are my weakest body part, heavy weight and low reps? low weigh and high reps? somewhere in between 4 or 5 sets of 8 reps … id like to hear from you about how you train biceps …
I train much the same way for all weights exercises, i.e. aiming for 8-12 rep sets and increasing the weight if I can do 12. That's definitely building up strength and endurance in all of my worked muscles. I don't specifically focus on biceps exercises at the moment, but I would guess that dumbbell and barbell curls would be your best bets if you want to focus on really making those muscles work hard. My biceps also feel like they've had an indirect workout after doing pull ups, but that probably isn't the most efficient way to specifically target biceps strength.
How have you determined that bicep is the weakest part of your body? Bicep curls are the best way to focus directly on them. Compound exercises that involve bicep are more likely to stimulate muscle growth: Pullups, barbell rows and similar. I had a few issues that I thought were due to weak biceps, but it turned out to be a combination of weak forearms, incorrect technique in training, and general all over weakness.
If my focus is on a martial arts competition, I do minimal bicep specific work, various rowing motions, and pull/chin ups take preference. When I'm training for physique I add curls, I split between high volume light-moderate weight drop/pyramid sets, and low(ish) volume heavy weights for a few sets of 6-8.
I rarely train arms. Chest/Shoulders works out Triceps, Back works out Biceps. So I would train the relevant body part. However if I do train a Arm Day - it'll be higher reps - middle weight (about 10-12 reps)
