it's all personal preference. if you go super low, of course you're going to scrape somethings. my cat scrapes more than anything else. but i have a pretty low drop (i'd say somewhere between 3 and 4 inches...i don't know for sure). but i would say that 2.5 is a decent drop that would hurt too much. if you're worried about stuff, i would say not to go below 2", but it's all up to you. (my pref is to drop it way down. i'm not a fan of wheel gap).