Not to get into the low-carb diet thing, but you really only need carbs when you need carbs. If you calculate the calories required for a 50 mile ride, it doesn't require much, if any, carb loading, but after the first 30 miles or so you would benefit from some minimal carbohydrate intake. The carbohydrates required before a very long ride, and during long rides, should not be confused with what works well for your overall diet and weight control (you didn't gain the 15 lbs while riding your bike). Tooling around the neighborhood requires little more than light protein replacement for an all out effort, and a glass of water for lesser efforts.