Is 50 grams a good weight for a male 5 year old leo. When i got him he only weighed 37 grams and they said he was a breeder! That was about 2 months ago.
What's his length? My adult female was 75 grams last time I weighed her, but she's almost 10 inches long. If your guy is more like 7 or 8 inches, 50 grams might be fine. Pictures would also be helpful; if his tail is in nice proportion to his body, you're probably doing fine. Basically, if it widens out significantly from the base to the middle of the tail without looking obviously OBESE, you're in good shape.
Mountain bikes are for slow people, and reptiles are far better pets than cats & dogs!