if u actually did some research this is one of the common flaws of the work out beginner.."I want BIGGER BICEPS!!"

first of all biceps only constitute 1/3 of ur arms..im pretty sure concentrating more on triceps exercises would help u more

secondly ur biceps wont grow to 18inches if ur thin everywhere else..its just defies the laws of human growth

in conclusion, try to concentrate on all areas of ur body and ur biceps will grow in proportion

regarding the wrist injury..my wrist is weak due to an old injury from playing basketball..

at first bicep exercises were ok but as i moved to heavier weights im facing difficulty as it just cant take the stress..there will be this sharp pain every time i do standing barbell or preacher curls..only thing that doesnt seem to be affected are the hammer curls as i can go quite heavy on those

any recommendations? my wrist strap doesnt help much..