General Cycling Discussion - how many carbs do you burn....

in addition to enjoying riding, i ride to lose weight. i was wondering how much carbs a body burns in any particular time as you ride. like say i have 15g of carbs before a ride. i ride 17ish miles, doing 15-18mph (on a mountain bike), did i burn all those carbs, or are they going to get packed away as fat when i go to sleep shortly after my ride. is there a way to figure out if i burnt all those carbs out. i noticed that if i limit my carbs too much my legs are very weak.
anyone have any info to help me out?
thanks

I just don't understand the whole less carb absession. It's much harder to convert carbs to fat then fat. I would be more worried about your trans-fats and saturated fat intake.
There is neutrition forums that you might want to visit. They might provide a more detailed answer.

Carbs = good...

for people that exercises. Pick up the latest issue of Bicycling magazine. There's one hint that struck a chord with me, which is that after you ride, you should replace the carbs you burn for your weight...however if you want to lose weight, change that calculation so that you replace the carbs for your target weight.

Low carb diets work for people that sit on their asses.

i know carbs = good, but what i am trying is this....
some may know that fat = 9kcal/gram, protien is 4, and so is carbs. when the body looks for energy it will grab carbs first, then go and look for fat, and some protein. when you ride you need carbs to provide energy for muscle, otherwise you feel weak and cant ride to your potential. what i am trying to do is give my body only the amount of carbs it needs for the ride. my schedual is strange, i work nights, come home, ride, and then sleep, those extra carbs arent good when you are at rest. i'm wondering if there is a way to find out how much carbohydrate a body will consume during a ride.

Ah!

Here's what they suggest you replace within 30 minutes of riding:

1.5 grams of carbs per 2.2 lbs. of body weight. For weight loss, reduce to match desired weight.

I guess the idea is that if you replace that, you are giving your body enough to recover without causing metobolic issues. I'm not an expert, I've pretty much reached the extent of my limited knowlege. I think what you are looking for is a preload carb figure so that you can get them in your body before riding.