I have a question - intermittently for several years now and for periods lasting several months, I've had an annoying uncomfortable 'tightness' in my right knee when riding. When I used to try and mix riding with running I don't recall any tightness but perhaps after moving increasingly further from my workspace I could only ride may have been a factor? For several years I was riding 5-15,000 k's virtually all on a rigid MB with a heavy duty bike rack carrying everything from chairs to 5-metre lengths of timber! (I always found it hugely amusing myself to see how much I was able to carry. Perhaps I should have got out more!) I felt a little panicked that I might not be loading my knees enough to keep them in shape or they were 'wearing down' in less robust areas of cartilage, my cycling action was too careless or something but there seemed little alternative.....
Anyway it's once more been 'tight' so I've felt too nervous to train much (I'm racing the MB-section in the team multi-sport Winter Challenge in Tasmania on Sunday). Dietwise I've been hugely enjoying fruit smoothies for breakfast and with plenty of fruit and wholemeal foods, etc. Do you have any suggestions? Perhaps (gulp...) arthritis?
No worries about the arthritis. I'm sure you will be clear.
Without knowing if there is swelling in the knee, it is possible that you have a tightening of the fibrous layers that encase the knee and which tighten during contraction of the quadriceps.
This may be exacerbated if you are cycling in cold weather and if pushing big gears. If you have a cadence meter on your bike setup use this to aim for a steady RPM of 80-90. When carrying heavy loads, or plowing into a headwind, the tendency is to stomp a bigger gear and drop the cadence to 50-60 RPM. This will grind the knees. Keep the legs spinning when under pressure and this will reduce torsional stresses on the knees.
Other possible factors are vitamin D deficiency which I understand to be rife in Tasmania during winter. Take 2,000 iu per day of one containing boron and selenium other than on days that you are sunbathing in your Borat swimsuit.
Iodine deficiency is widespread as well unless you are a daily consumer of seaweed. This can result in hardening of connective tissue. If you obtain some standard iodine drops, take about 20-40 drops each morning and see what happens over the next three months. Another possibility is a deficiency of zinc and molybdenum which are essential for healthy connective tissue and for healing. You could take this twice a day. Hard exercising athletes need these more than sedentary types. A Hair Tissue Mineral Analysis is the best tool for determining your exact needs but what I am recommending here is a good start.
Finally, try getting a deep tissue massage of both thighs, including the knees. Make sure it is by a trained person who knows the difference between nerves and blood vessels in the back of the leg and gristle. Get this done once a week. This last piece of advice applies to all cyclists, injured or not.