Also if i just want to tone my body how long should i be riding a day? Should i keep the tension low and ride longer? Will this tone my whole body or just my legs?
If you are using the exercise bike corrrectly and sitting correctly, then you should be able to feel a slight pull on your hips and lower stomach too.
As a rule of thumb, I always say that if you are sweating then you are burning up fat. You have to do what you feel comfortable with, but it is okay to push yourself just that little but further.
I just want to say, that I am no fitness expert, this is just my opinion!
I would say that how long really depends on what kind of workout you want to try to get. For cardio I would go with less resistance on the gears for a longer period of time, say an hour or so, and for muscle building I would do a lot of resistance in shorter spurts.
It depends upon you.You should have some instinct which says it is better for you.I would recommend you to generally keep the tension low and ride longer.