@SylvainG - I have a similar distance commute, am about the same size as you and eat about the same amount or more. I also do some weight lifting and running (sometimes a lot of running if marathon training).

Before bike ride - cereal, usually a bigger bowl than the normal "serving size".
First thing at desk - banana and either Clif bar or granola bar (or two).
10am snack - PB crackers, trail mix, cheese sticks, yogurt, whatever I may have.
Lunch - usually a sandwich I make (PBJ; deli meat) or leftovers from home.
Afternoon snack - similar to 10am snack. Or cookies.
Before riding home - apple
Once home - anything I can find varying from something kids or wife baked to chips & salsa.
Dinner
Before bed - maybe some ice cream

Also, I drink lots of water. I don't drink coffee or tea, only the rare (well, once a week-ish) soda. Gatorade or lemonade sometimes.

Biking alone will not cause me to lose weight, probably because I snack a lot. But if I run and lift regularly on top of my commute, I would lose if I didn't consume the calories.