If your goal is to lower your body fat you may wish to consider doing some cardio in the morning prior to eating. Like a 15-20 minute interval about 12 hours or so away from your workout in the evening. Try it for a month or so and see the results. It shouldn't be enough to consume the muscle you will build due to it's short duration and separation from your training time. The key is intensity during the interval - think sprinting, not jogging and make sure you are medically up to it.
Keep some distance records from your machine rather than calories. This will give you a target to beat each time. I use a manual cardio workout that is as follows:
20 Minutes Total
Minute,% effort
0,50%
1,50%
2,60%
3,70%
4,80%
5,90%
6,50%
7,50%
8,60%
9,70%
10,80%
11,90%
12,50%
13,50%
14,60%
15,70%
16,80%
17,90%
18,100%
19,50% cool down
(Just enough time to watch a TiVOd South Park too!)
This is adapted from a workout by Bill Phillips.
Good luck!