161 is a good cardio rate. If you can hold that for a good 45-60 minutes, you're getting a really good workout. Just remember, just like weight lifting, your body will become conditioned to that and could peak, so keep making changes. Some simple things are increasing your resistance, adding intervals, shortening the time and going for a higher AHR (average heart rate), etc. Always look to improve each time you do cardio to prevent a plateau.
Keep it up Dave, that's a good accomplishment!