Hi, I know that most XC stems can be used upside down. But some people have posted that 'some' DH stems aren't designed to be flipped (and they can fail or snap) I have an Easton Vice stem : http://www.eastonbike.com/PRODUCTS/STEMS/stem_vice_'08.html I was wondering how do you know a particular stem can or can't be used upside down ? What's the rule of thumb ? Thanks. .