Finally i've understood the technique demonstrated in the Dillon's video.
At the beginning i wasn't able to understand the motion.
i have a long journey in order to clean the form but combining the inverted chin up with biceps curls is a good way to start multiple reps while improving the degree of biceps curl in the final version.
Progress are very slow, the stress on the forearms is high (probably on the 5x5 day i do one negative in 3 second and a concentrich in 2 seconds, so for 5 reps is 25 seconds tension for the forearms always on false grip) and some more stretching is very good to balance all the contractions.
I can remember when it was only a dream.
I'm starting to feeling it a true goal!