As the weather becomes more conducive to riding, the racing season gets going, and average weekly training distances start to climb a few of us will have some trouble with our knees. Usually knee problem are caused by one of four things:
    1) Riding too hard, too soon. Don't get impatient. It's going to be a long season and there's plenty of time to get in the proper progression of efforts. Successful cycling is a matter of listening to your body. When you see cyclists burning out, hurting themselves and just not progressing past a certain point you can be fairly certain that it is because they are not paying enough attention to what their bodies are saying.

    2) Too many miles. The human body is not a machine. It cannot take all the miles we sometimes feel compelled to ride without time to grow and adapt. Keep this in mind whenever you feel like increasing average weekly mileage by more than forty miles over two or three weeks and you should have no problems.

    3) Low rpms (also excessive crank length). Save the big ring climbs and big gear sprints for later in the season. This is the time of year to develop fast twitch muscle fibers. That means spining. Not all the time but often enough to feel comfortable at high rpms and, ideally, not as comfortable at low rpms. Small gear sprints and climbs now will pay off later in the season. Mountain bikers need to be especially careful of low rpms. Even full time MTB competitors can benefit from doing most of their training on the road.

    4) Improper position on the bike. Unfortunately most bicycle salespeople in this country have no idea how to properly set saddle height, the most common error being to set it too low. This is very conducive to developing knee problems because of excessive bend at the knee when the pedal is at, and just past top dead center.
If you've avoided these common mistakes yet are still experiencing knee problems first make sure your seat and cleats are adjusted properly then:
    1) Check for leg length differences both below and above the knee. If the difference is between 2 and 8 millimeters you can correct it by putting spacers under one cleat. If one leg is shorter by more than a centimeter or so you might experiment with a shorter crank arm on the short leg side.

    2) Use shorter cranks. For some riders this helps keep pedal speed up and knee stress down. I'm over 6 ft. tall and use 170mm cranks for much of the off season.

    3) Try the Fit-Kit R.A.D. cleat alignment device and/or a rotating type cleat/pedal system.

    4) Cut way back on mileage and intensity (This is a last resort for obvious reasons). Sometimes a prolonged rest is the only way to regain full functionality and is usually required only after trying to "train through" pain.
Roger Marquis ( See also rec.bicycles FAQ 9.25