My tendonitis had had enough time that I wasn't having any pain anymore so I decided to give it another shot and go even slower. I just walked fast enough to get my heart rate to the 60-7-% fat burning zone. Did 5 miles in 2 hours. According to the treadmill, burned 866 calories this way.
Also, I found
this site which had some interesting stuff about target zones. I figure by the nature of it and how out of shape I am, I am getting well into the aerobic and even anaerobic zones on the bike. So using the treadmill for the fat burning zone and the bike for cardio benefit seems to make sense for me right now. And the low speed on the treadmill will be easy on my foot. I was only at 2.7 mph. Just a stroll really.
Also have a Polar heart rate monitor on its way that I got on ebay ... so I will know where I'm at on the bike.