Unless you've got a link attached to your site and it interests them - assuming they see it - it's just another dud message that lands in their inbox. I'm sure those guys are pretty busy with requests landing in their inbox from unknown people. Hipster, even when people are hipsters, doesn't usually come with an attractive connotation here so I'd probably avoid using it in the headline.
What I will say is, even if you don't get in touch with anyone online, if you go and skate the right places in NYC you'll probably run into some of these guys over a weeks course. In person may be your best bet.