In 2007, Walt Siegl left New York, his home of 20 years, and his career as a cultural representative with the Austrian Ministry of Foreign Affairs, to move to an old textile mill in New Hampshire. There, he turned his hobby of souping up Italian motorcycles into a full-time job. Now there’s a two-year wait for one of his impeccable custom machines. (Brad Pitt is set to receive his third creation by Siegl, whose bikes are coveted by connoisseurs for their stripped-down elegance and structural perfection.) ‘‘I take the time to pay full attention to every detail, to show mechanical components as objects of beauty,’’ Siegl says.

In addition to one-of-a-kind custom projects, he also offers ready-made models: the sleek Leggero, the chunkier Bol D’Or and the new off-road Adventure, out this month. For all three, Siegl takes apart brand-name bikes (Ducati and MV Agusta) and rebuilds them with specialty materials — Kevlar and carbon fiber in place of plastic, chromoly in place of regular steel. The result is a drastically lighter, more technologically advanced machine. On the bikes’ fuel tanks, Siegl affixes his trademark, the outline of a wheel with a flower at its center that’s inspired by childhood memories of picking wild blooms for his mother near their home outside of Graz in southeastern Austria. ‘‘When I came to the States, I couldn’t believe how much attitude is involved in motorcycling,’’ Siegl says. ‘‘To ride, you need to have a big heart. There’s no need to act tough.’’ — SAM DEAN