This is what I use when I feel like I can do it:
Stamina Magnetic Resistance Recumbent Bike
http://www.walmart.com/ip/Stamina-Ma...t-Bike/7680164
I have to watch my pulse rate closely to make sure it doesn't go up to much as that messes with my head.
Sometimes I can takes walks; sometimes not.
This is the extent of my exercise since PCS.