I had a ACL and cartilage operation on my knees in 2006 and 2007. On advice of consultant bought cross trainer which also is a bike (two in one). It is the best thing I have bought. There is no impact on the knees, and my times have got better and knees stronger. Listening to good music and playing football for 18 months has made me improve my times. There is also no fatigue or aches on the legs.

Just thought I would share that with you.