eavonius

When doing the knee over pedal spindle measurement, I see some folks say it should be measured from the front and center of the kneecap itself, others that say you should measure from the little "bump" below the knee, and some that say to use the fleshy spot in between these two spots. I'm curious what y'all use and what your rationale might be behind it.

Thanks!

AEO

doesn't matter, as it only gives a base position from which you can work on.

KOPS is a myth, since center of weight can vary greatly between two people who are 5'8, but with one person having a long torso and the other having long legs.

jrobe

"KOPS is a myth"


+ 100, Gravity is not a factor in bike fit.

DaveSSS 

Experts like Andy Pruitt still use KOP, at least as a starting point. He drops the plumb bob from the very front of the knee to the end of the crankarm, not the pedal spindle. Of course the bike must be sitting level when this is done.

I always have my saddle further back for better weight balance over the saddle and little weight on my hands.

RacerX

kops is a generic fit measurement, not really accurate. There are some that even ride/race with their pedal in line with the leg bone, near mid arch of the foot.

You need to go with what feels comfortable and works with your biomechanics

Randochap

This and that.

ImRael

Mine is a line between the center of the pedal spindle and the most distal portion of the lateral condyle of my right femur. It is a point of reference.

z415

I think KOPS is an average and as we may all remember, an average could be a value that no one in the population actually has. That said, I have my knee plumb bobbed right at my front toe.

eavonius

I know KOPS isn't exact and doesn't work for some cases. I was simply asking for people who do KOPS, where they drop the plumb bob from, not where it lines up on your foot/crank/pedal etc.

Flatballer

If KOPS isn't exact, then why are you worrying about a couple mm of where you're dropping the plumb bob from?

Hendley

Soft bit under the knee cap, for what it's worth--which is nothing, because foot angle, hip angle, position in the saddle, ground slope, etc all combine to make the margin of error on this measurement a lot greater than the few millimeters or so between different areas at the front of your knee.

daxr

Yeah - that's it.

khatfull

Ok, so we've established that KOPS is a starting point. But how does one know where to go from KOPS and why? What do I look for that would indicate that I need to move the saddle fore or aft of KOPS?

daxr

You can look at knee comfort or hand comfort if those are issues, but usually I think of the fore and aft positioning as balancing the weight of the body over the bottom bracket in a way that allows for efficient use of the whole body pedaling. Ideally, I can pedal away comfortably and efficiently stretched out and pushed a bit toward the back of the saddle. I can put in a good effort by "tensioning the core" and applying more force to the pedals, while still breathing well in the middle saddle position. I can edge toward the front of the saddle and kind of coil up and pedal in a hard effort, usually at a tough point during a climb.

All of those three require the saddle position to relate well to the bar position, and if they all work well its probably ok. Experimenting is hard if you are just pedaling around, as there are many positions that can feel fine if you're not doing long distances or hard efforts.