When I commuted my 28 miles RT, I would call it quits at 25 or so, although sometimes in the early am it was colder than that. However, waiting for the bus in those temps was worse than riding. I enjoyed riding in the cold, once I learned the proper layering system (Pearl Izumi lobster gloves, by the way, are the best for me).

Now I'm a bonafide wuss. I moved south, slightly, and work from home. I no longer have a commute to work. I thought, great, I'll just go for a bike ride!. Not happening, except on nice weekends.

Thank goodness for spinning, is all I can say.