As others have said, get into a comfortable stance thats what matters most.
Typically most people have the best balance with ducked feet, although many people just don't like that feeling for extended periods of time being strapped in.
Your best bet if you really just dont know is to do a quick run skip and hop and then land on some paper or something and mark the sides of your feet to get approximate angles...you will typically land with your feet in your most comfortable position unconsciously because you've done it so many times before in your life. Or figure out how you would position your feet if you were squatting to pick something heavy up...Its really all about comfort..
'09 151 Never Summer SL-R
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