Just food for thought:
- “Ideally Q-Factor would mimic running stance, that is, a very narrow foot placement” - I don’t buy that jump in logic, from my own experience with cycling and running biomechanical analyses. Firstly, the hip position is drastically different in cycling vs. a walking/running gait. On a bike, especially in an aero position, the hips work entirely in a range of motion of hip flexion, vs. passing through neutral and even an extended position in bipedalism. The orientation of the acetabulum (hip sockets) greatly changes the available, and optimal range of motion for the femurs. If you compare the same ranges of motion of the hip joints in supine with the hips in neutral vs. a flexed position, you’ll find wild differences, and not necessarily predictable differences. That same logic applies to changes in the length tension curves of the hip and thigh muscles.
When walking, a normal stance width is about 4-6 inches. When running it is usually zero, meaning that the feet essentially land one in front of the other. That would seem to support the notion of a more narrow foot placement, but running is different, we are only weight bearing on our two feet. To improve economy of motion, we narrow the stance width in running to land our feet directly below our center of gravity (between the navel and lumbar spine, typically). This decrease the moment/lever arms of the width of the pelvis and decreases the load of the hip abductors as they stabilize the relationship between the lumbar spine to the pelvis, and the pelvis to the femur. We don’t have to do that in cycling though, our center of gravity is already supported, by the saddle, and by bilaterally simultaneous weightbearing through the upper and lower extremities. So the benefit of a narrow stance width is lost in cycling, except to improve aerodynamics. I would guess there is research to support this, but my own experience is that people generated more power, in more comfortable position with a stance width that is at least that of their walking stance width, if not wider. I don’t think there has been enough adjustability in options of current gear to allow sufficient mass practical application to make a blanket statement about though.
We rock the bike side-to-side when out of the saddle because we remove the support from the center of gravity (on the saddle), and revert back to a our walk/run gait strategy, only now since our primary areas of weight bearing, our feet, are in a position of fixed width, so we can only bring them under our center of gravity by rocking the bike sideways, and bringing the pedal under the COG. You can ride out of the saddle without rocking, but you’ll feel a hell of a lot of strain through your lateral hip and core musclulature as the deal with the increased lever arm between the axis of motion (hip joint) and the base of support (saddle vs. pedals). try it.
There is no optimal Q angle. There are too many individual human and mechanical models. In my clients I like to see a straight line from hip, through the knee, ankle and second toe, and the lower limb tracking on that line, which doesn’t have to be vertical. That’s just a blue print though. The positioning has to be altered based on individual variances, goals, abilities, (blah blah, heard it before).
Try a single leg press where you are sitting with back supported. play with the position of your foot relative to your center of gravity and see where you feel the most power generation with least amount of joint stress. It would not support the very narrow stance width theory.
Cheers,
Bruk
I do like the concept of adjustability though. That’s what gives us the ability to accommodate all of those individual variances.
