|Proper KOPS measurement???||andydave|
Feb 16, 2003 3:25 PM
|When making a KOPS measurement, do you put your feet in their natural pedaling position, or do you put your feet horizontal (like the crank arm)? At various web sites, I have seen it stated both ways. Obviously, both can't be right.
I tend to ride with my toes pointed downward. With my current set up, my knee is a good 1.5cm in front of the spindel when my foot is in its natural position. But when I lower my foot to horizontal, my knee is right over spindel. I was surprised to see how much difference it makes.
Any input would be appreciated.
|Are you sure?||Kerry|
Feb 16, 2003 6:43 PM
|You say you know what your foot position is during pedaling, but unless you have slow motion video to prove it, I highly doubt your toes are pointed down as much as you think. There have been many reports where people thought their feet were one way or the other, and the video shows them to be "mis-perceived." The standard way to measure your knee relative to the pedal spindle is with the foot horizontal. However, this is only a starting point with personal comfort and your desire to spin or push coming into play, along with physiologic factors like femur length.|
|Are you sure?||andydave|
Feb 16, 2003 8:31 PM
|No, not totally sure, but you are probably right. When taking this measurement, I spin on the trainer and stop when the cranks are horizontal. This is relatively easy. But then that got me thinking, when is the foot horizontal exactly? Is it when the cleat surface is horizontal? If so, the heel of the foot is kicked up slightly. Unlike when you walk where the heel and forefoot basically fall in the horizontal plane. I may have been assuming the same thing applied to the bike (which I don't think it does).
What do you think?
|High-speed camera study||micha|
Feb 17, 2003 3:25 AM
|In his book "Science of Cycling," the late Ed Burke cites a study on foot position. High-speed cameras were used to look at the angle of the pedal in relation to the crank, with the pedal surface at 90 degrees to the crank defined as "horizontal foot postion."
With elite riders pedaling at 100 rpm and generating 400 Watt, the extreme slow-motion films showed that the mean for all riders was 105 degrees (heel slightly down) at top dead center, and 50 degrees (heel up) at bottom dead center. Several riders deviated from this mean quite a bit.
To add another complication to this, more recent studies have shown that pedal angles for one individual vary quite a bit for different cadences.
I think this shows that KOPS is, as Kerry has pointed out, a good starting point only. (Keith Bontrager completely dimisses it in his article "The Myth of KOPS".) Your KOPS is set with the crank arm horizontal, but at zero cadence, zero power output and with you not knowing your pedal angle at speed on the road. So it's not much of a scientific setting, actually.
I would set "KOPS" once with the plumb bob, then listen to my body and fine tune my position.
BTW, my knee moves 2 cm from "KOPS" depending on my pedal angle - and my pedaling style for climbing differs wildly from the one I use spinning on the flats.