A Case of Real Bad Knees
I’ve been biking and and swimming for as long as I can remember, and running since my twenties, but it has only been in the last few years that I have felt any pain in the knees. Aging may be a contributing factor. Another may be that I essentially stop running when I’m biking a lot. Or it may be the bike.
For the last several years I’ve been riding to and from work – about ten miles each way – several days a week. My early route involved several steep hills. I initially managed with no pain, but after a few years, I was finding it painful to climb the stairs at work after riding.
Last summer I switched to a less hilly, slightly longer route, which helped. I also switched from a single 53-tooth chainring to a 50 and 40 in front, which helped in climbing hills. I’ve also tried to be diligent about not pushing big gears. But I still had some pain.
A lot of articles on knee pain advised that pedaling with your legs too straight or too bent can put too much pressure on the joint. Other articles claimed that cycling itself over-exercised some leg muscles which then overwhelm other leg muscles and hurt the knee. This Active article is typical of those:
The VMO, or vastus medialis oblique, is the teardrop quadriceps muscle that runs along the inside of the thigh down towards the knee. In cycling, the vastus lateralis (quadriceps muscle on the outside of the thigh) often becomes overdeveloped, resulting in a muscular imbalance. The overpowering of the vastus lateralis can make the kneecap track too much towards the outside of the femur during pedaling, which in turn wears away the cartilage and causes pain.
And here’s another from Bike Radar:
Those ‘large muscles of the thigh’ can get very large with regular two-wheeled activity, and this is where problems start.
The normal movements of the knee are ﬁnely balanced, and with different muscle groups pulling at the patella from slightly different angles, it doesn’t take much to upset things. Add to this tight muscles restricting normal motion, varying saddle heights and feet ﬁrmly planted in angled cleats, and it’s amazing we don’t all cycle with ﬁxed grimaces.
I ride a Xootr Swift in an upright position. It folds by removing the seat post, so there are two quick release clamps on the post. When you unfold the bike you have to estimate the height of the seat post and clamp it. Despite the two clamps, I have often found that the seat slowly drops as I ride. Tightening the quick release only slows it down a bit.
According to a second Bike Radar article, and many others, pain at the front of the knee is usually blamed on a saddle set too low, or long crank arms, or pushing big gears. Pain behind the knee is rarer, and usually blamed on a saddle set too high, or too far back. Because I was stopping several times to raise it, my saddle may have been too high at times, and too low at times. But the pain feels more anterior than posterior, so I suspected pedaling when the saddle was too low was the problem.
A few months ago I measured the saddle position on my Serotta. All Serottas were custom-fit, so I figured that maintaining the same saddle distance from the crank would be ideal. I set the Swift saddle to 31.5″ from the center of the pedal axle, and added a pipe clamp to keep the seat post from dropping. The last few months were challenging due to a snowy winter and a pulled hamstring, but it seemed that my knees were improving over the last three weeks of riding again.
Sunday night I measured and found that the saddle had migrated two inches lower over the last few weeks. So I set it back to 31.5″. Riding on Monday I felt more power in each leg stroke, but also some twinges of pain, particularly in the back of the left knee. I also felt some discomfort climbing the steps at work. Pain in the back of the knee tells you the saddle is too high, so last night I set the saddle down to 31″. We’ll see how it feels tonight.
Update 20150415: Riding was pain-free with the saddle at 31″, and climbing the steps at work is less painful than yesterday.