This is likely to be patellar chondromalacia if the pain is the
cartilidge under the kneecap and not in the muscles or tendons
surrounding the knee. This is caused by uneven development of one of
the mucles connected to the kneecap. This pulls the kneecap out of
alignment with the cartilidge lined groove of the femur resulting in
inflammation and pain. For cyclists the overdeveloped muscle is the
innermost vastus medialis oblique (VMO).
I have had this problem for two years now. It started in my dominant
right leg and got to the point that it was painful to walk up/down
stairs and put on shoes. My remedy for this was to wrap an ace bandage
directly under the knee in such a way that the kneecap is pushed up and
can't ride on the inflamed parts of the knee joint. It helps if you
learn to stop tensing the VMO during the power phase of each pedal
stroke. I also changed my technique for starting the bike from a stop.
I now get into the saddle quickly before the first downstroke so that I
can better regulate the amount of force applied to the knee. I worked
on training my left leg to take on a more equitable share of the work.
You will have to make sure that the gearing is low enough that you
don't have to use a lot of force in the downstroke. You will have to
become a spinner if you are a masher. Clipless pedals can help if you
don't already use them since they allow you to spread out the power
phase along the bottom of the stroke, reducing the maximum load on the
knee. You can also pull up with clipless pedals and although that isn't
sustainable over the long haul it can help you limp home if your knee
is in too much pain to push on the pedal. In my case the pain would be
aggravated whenever I hammered near the peak of my capacity. Without
care, a weeks worth of healing could be undone in a single ride. You
need to have the discipline to ride below your capacity most of the
time. My biggest problem is that I heal to the point that I loose the
feedback from a pain response and go out and ride too hard, causing a
setback.
The best way to let things heal is to not ride at all for extended
periods. I gave up commuting for a few months and limited myself to one
ride a week during the winter. I found the weekly ride was sufficient
to maintain conditioning such that I didn't have to work hard to
restore capacity in the spring.
My knee has improved to the point that I can use the knee straps
designed for this purpose rather than the ace bandage. My left knee
started showing the early signs of pain this year so now I use the
straps on both knees. They are both in much better condition. While I
am not pain free, I can climb stairs without much trouble and putting
on shoes is not excruciating.
For the longer term, it helps to work on developing the outer vastus
lateralis by performing leg lifts that target those muscles. A sports
medecine therapist can give the best guidance in this matter. There is
a fair amount of information on this problem on the web. Some exercises
are shown here http://www.orthoseek.com/articles/chondromp.html.
