Weight / Fat loss

So for big rides (weekends) I should ideally carb load and keep eating the carbs on the rides.

But for commuting 20 miles each way, carbs really aren't really that important? This is mainly for weight loss and getting fitter, I can then stick to my usual diet with low carb intake which should aid weight loss.

Stop trying to classify food types so much. Calories is calories. The reason carbs are popular for cyclists/runners is that they replenish glycogen stores in the body efficiently because sugars & starches are not so different from the glycogen stored in your muscles & liver.

Excess calories from any source can be stored as fat.

Carbohyrates are useful for post ride/training recovery as they trigger an insulin response. This helps usher nutrients like amino acids (protein) in your diet to the necessary parts of your body for repair/building muscle proteins.

It is still however totally possible to be extremely healthy & fit with almost no dietary carbohydrate. This is actually fits our evolutionary biology better than relying on grains & potatoes for so much of our calories.