Originally Posted by Bill Kapaun

You want cheap! I just installed these-
http://www.nashbar.com/profile.cfm?sku=20985

See my thread- Read my initial post and then skip to yesterdays to avoid a lot of tedious reading. Basically, that'll be before & after.
http://www.bikeforums.net/showthread.php?t=361045

It amazes me how people without bad knees try to advise someone that has bad knees.
For those people, it's really simple- BAD knees don't BEND as much as GOOD knees!
The whole torque leverage thing is bogus. You just use a lower gear! Power to the rear is theoretically the same. In reality, it's better because you are pedaling MUCH more efficiently.