I used a convert hard shell that I owned for some time. I bought it one size too big so I could layer underneath for when I went to the mountain. It worked pretty well but the water proofing was starting to not work any more. This winter came around and I was swimming in the jacket because I had lost weight form biking. I bought a medium sized jacket from Showers Pass (www.showerspass.com) and am very happy with it.

From an essential point of view, biking and snowboard shell jackets are very similar as far as fabiric and ways to vent heat. But unless you live in a very very cold environment or snowboard more than you bike, I would stick with a jacket designed for biking. Just makes sense, they are thinner because well, bikers work hard than boarders plus often there is reflective tape and the tails are cut a little longer.