Any Mountain Bikers Out There? Need Nutriton Input Please

GymRatGirl13

Hey there MFP peeps! I am looking for some advice on nutrition for mountain biking. I am new to the sport and am absoluely LOVING it. I am riding 5-6 days a week, riding anywhere between 3-10 miles, with the majority of the mileage being climbs. I live in Montana and am surrounded by various mountains, so I am fortunate in that department. :-) I am adding in a day of steady state riding on a flat surface, just to work on riding for longer periods of time (30+ miles is the starting distance). I am coming from a nutrtion mindset that served me very well with my last hobby, which was figure competing. I lived in the gym, lifted heavy and hard 5 days a week and did HIIT cardio once or twice a week. So, I am used to eating to repair and build muscle, while shedding or maintaining body fat levels. High protein with every meal, minimal carbs except post workout (where I would eat most of my carbs and would eat simple, quick carbs) and moderate fat. I would only consume enough carbs to get me through my day and to fuel my workouts. On rest days, I would drop carbs and add fat. I have been biking for three months now and am doing fine on my current diet, but would like to improve at biking and feel that I probably need to make some adjustments to my diet to fuel my workouts better. I have read a ton on it, of course, but would like to know what you guys do. Is there a need to adjust my current diet to improve endurance and power, or will I continue to get stronger without making any adjustments? Do I NEED to add carbs prior to my workout, or just consume some quick carbs during my longer rides? Right now, I am used to fasting for the 2-3 hours prior to lifting or riding. Does it help with energy, without gaining weight, to add a quick carb right before the ride? Any advice would be greatly appreciated.
Oh...and I have been eating about 1800-2000 calories a day for the past year and have maintained my current weight of 145. I am 5'7". Since adding biking to my routine, I have actually gained a couple pounds, but haven't changed anything. I am not a number freak and don't care about how much I weigh, I am just wondering how it is possible to gain weight when I am buring anywhere between 300-800 more calories in a day, yet not consuming more. Hmmmm. Thanks all!