How to keep balance when doing hanging leg raises

Sorry if this isn't allowed here

when i'm doing my ab workout i have to do sitting leg/knee raises, which isn't a bad thing but i heard that hanging leg/knee raises are more effective as it's a bigger stretch.

when i attempt to do them, when my knees/legs come up my body swings like mad, i've tried gripping harder, going slower, what's causing this? anyone have the same issue