Try to flex the long head of the bicep. Can’t really do it can you?
Just lift hard and use various exercises and grips. Different exercises and grips use different recruitment patterns. The reason you won’t see too many guys in the gym doing incline curls is because they are hard and require more effort thus you’ll have to reduce poundages. Of course your muscles don’t care about poundage, only about force.
You want a peak?
Step 1: Get a knife and a piece of string.
Step 2: Cut up your arm so you can reach your bicep tendon insertion point.
Step 3: Cut off the tendon at the bone. This might hurt.
Setp 4: With your peice of string, or maybe a soldering iron, attach the tendon closer toward you.
BANG. Now you got a peak…
It’s genetics. I’m small as fuck but have a pronounced peak, especially in the right arm. Also, lose bodyfat. You may not see a peak because your arms are too fat.
You could always try to shorten your limbs? That seems to work wonders. Just get a hacksaw and a blow torch…