Originally Posted by
hshearer
For feet, say yes to loose shoes; you need air in there to stay warm. If you're riding with clipless, try some insulating insoles ("toasty feet" at Wal-mart might be thin enough?; I bought the thermal insoles Mark'sWork Wearhouse sells, but they made my shoes too tight. If my shoes had been one size too big they probably would have worked. I wore them with my husband's shoes (2 sizes too big), and they were great); the metal plate steals a lot of heat. I also find plastic bags over my socks cut the wind and keep my feet warm. There are also chemical packets and battery powered socks you can try (Canadian Tire, Mark's) if insulation alone isn't working for you.
Depending on his pedal configuration, how often he plans to ride in these conditions, how attached he is to clipless, and how much money he's willing to spend, a set of waterproof winter hiking boots might serve him. You can get a set good down to -32C for $100 or less. I can say from experience that they work well and remain comfortable at indoor temperatures.