Interesting fitting issue
 

Hello everyone,

I have been trying to fit my girl friend on her bike for a while now. We are finishing up college, which is why we have not spent the big money on an intense bike fit yet.

The problems I am seeing. Her hips rock, no matter what I do. Over the past 2 years we have moved her saddle up and down all with no change. Recently checking her knee over spindle, we found out that when her right knee is over spindle, her left knee is about 2cm behind the spindle given the same saddle position. She does not seem to have a leg length difference, she was a competitive ncaa cross country runner for a while, with no known issues. I think this may point to why we have hip rocking. Any thoughts on what could be causing this?

maybe its not bike fit just the "style" of her pedal stroke.

Does the hip rocking cause pain?

There is no reported pain from the hip rocking. It just seems strange that her hips rock.

always liked the view ..

Would not worry. Though what is her spinning speed? Many pros rock their hips when doing a high effort time trials with somewhat lower from normal rpm's.

Your measurements of her KOPS and total leg length suggest she has a right femur that is longer than the left, but interestingly her tibia is longer on the left to compensate for this. This may cause her hips to rotate about the central axis of her body and may look like her hips are rocking up and down. You should observe her to see if this is the case. If so I would set the KOPS to be the average of both legs that way you minimize the effect of the femur length difference. However this rotation of her hips may be her normal riding form and if she is not having pain, then it works for her.

I was gonna say that it only looks like her hips are rockin' because you're lovin' looking at 'em!