Seat Height Question



jwroubaix

Member
Jun 6, 2007
177
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I've been trying to get a better fit on my bike and the biggest thing i'm having problems with is saddle height. If a seat is too high what are the symptoms? Pain where? If it's too low where do you experience pain. I've read on here that your leg should extend about 90% at the bottom of your stroke. I lowered my seat recently and am getting a little pain in my knee.
 
Some symptoms: pain (location varies), smoothness in cadence decreases (perhaps start wobbling in seat), power decreases. Typically it's stated that the "knee angle" should be between 25 - 35°. The landmarks for measuring are the lateral malleolus of the ankle (big bump outside of ankle), the lateral condyle of the knee (big bump on outside of knee), and the greater trochanter ("hip point" or big bump on hip. Note that the hip is not the pelvis but the proximal--closer to the heart--end of the femur). Obviously this produces to line segments roughly following the femur and very roughly the tibia. The "knee angle" is measured as 180°- the angle between those two segments. So if you actually measure the angle between those two segments you should, if you follow the typical advice, get an angle between 145 - 155°. Be careful to not make big changes in saddle height as this can cause injury in some people. It's generally best to change the saddle heigh buy a few millimeters at a time......0-4-ish.
 
Couple of things to try with your leg to see if the length is about right...this will give you an approximate length.

1. With your leg straight and the pedal at the bottom of the stroke (in line with the seat tube), the top of your foot should just slide underneath the pedal. Hence with your foot on the pedal your leg is slightly bent.

2. With your foot on the pedal at the bottom of the stroke, gently try to straighten your leg with your heel having to go down. You should be able to straighten your leg like this and not have too much bend in the ankle. A photo would be good for this one. When I tried this at the shop recently during a fitting, I could straighten my leg OK but they said my saddle could be a smidge higher.