Hi picard120

I would forget about all the so called performance enhancement sporting beverages, they are pointless. A banana, a marmalade roll and some diluted fruit juice is much more beneficial and cheaper also.

As for building up the leg muscles, leg muscle mass has nothing what so ever in Mountain bike performance because it is essentially an aerobic sport. Its all about how efficient your cardio vascular system is i.e. your resting heart rate and the maximal oxygen volume of your physiology. i.e the maximal power output versus your weight.

I wouldn't bother with the creatine stuff either, fish and chips tastes better and has more nutrients also.

If you have a balanced diet you don't need any nutrient supplements either.