Have you had your bike fit checked by someone who's really good? Improper saddle height exacerbates Pattellar tendonitis.
http://sweatscience.com/cyclists-adj...-bone-density/
http://www.cptips.com/knee.htm
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.