I've long suspected that Knee-Over-The-Pedal-Spindle as measured with a plumb line has no basis in real science. Keith Bontrager's essay pretty much confirmed this for me. https://sheldonbrown.com/kops.html That aside, does anyone know where exactly are we supposed to hold the plumb line? The leading edge of the knee cap does not seem to be the mechanical center or fulcrum of the knee and neither does the Tibial Tuberosity below the knee cap. I find that pretty much anywhere I hang that pendulum on my knee, the line falls very close to the pedal spindle. That is true on a road, track, and CX bike with three different crank arm lengths and differing seat setbacks. If the "correct" position of that line is a matter of millimeters, then the point where the plumb line originates needs to also be exact. I am really wondering HOW to assess the bio-mechanical impact i.e., what is most efficient and least likely to injure?

French rider and coach Cyrille Guimard fit himself and his riders considerably behind KOPS. He said this put the hamstrings in position to apply more power. Of his most successful riders, Hinault, LeMond, and Fignon, only Fignon never had knee problems.

Australian fitter Steve Hogg says don't worry about the knee's relation to the pedal spindle because it's all about balance. That is, after setting the saddle height, the hips should be no farther forward than what's comfortable for the back muscles to support the torso without the help of the arms, and then readjust the saddle height. Once the torso is comfortably balanced and not causing excessive energy expenditure, the legs will adapt to the position and use that saved energy to turn the cranks more effectively. This philosophy has been working for me since the late 1970s. Because I still have a swimmer's torso, this puts me a little behind KOPS. And I don't have knee problems.

The thing about pedaling a bicycle is that it's a dynamic activity, the body adapts, and getting too precise about static hip angles and knee positions can be a dead end.

KOPS hurts my back. Every single time. I won't let shops that use it fit me anymore.

I have yet to meet a 'bent rider who doesn't fit himself way, way behind KOPS

What do you find to be an acceptable method and where does that put your knee with respect to the crank/BB?

Here's one that's way way ahead of KOPs. https://www.bbc.co.uk/news/technology-24015622

I sprang for a Retul at a great shop and they helped me tweak it a bit after feedback. I honestly have no idea where my knee is relative to the BB, sorry. The shop didn't do that and I wasn't curious.

Ha ha. But they don't have to worry about using their back muscles now, do they?

This ^^^
Really well articulated and same for me. I also ride well behind KOPS. I completely agree with what you wrote. I also train on a 29er with flatbar. Last night, I brought my allen wrench on my ride and fooled around with setback on the bike. I was pretty astounded as to the difference in my power and balance between forward and aft saddle position. I believe those that blindly adhere to KOPS or believe they need to be in front of KOPS to open their hip angle, they are missing out.

I might add that the other part of the Guimard formula was long cranks, bigger gears, and lower cadences. In my mind this caused more problems than the saddle setback.

fore aft saddle position has long been a puzzler for me. ive tried kops with so so results so for me its been 1) adjust seat height by lemond formula 2) try KOPS and adjust as necessary. i make adjustments based on saddle feel. if it feels like its chaffing, i know the wide part of the side is pushed to far forward. if it feels like im sitting on a broomstick i know its pushed back too far back. ive found it helpful to use the same saddle if you have multiple bikes. i only use specialized romin evos now and have found that saddle 3 inches behind the bottom bracket is my perfect number. from there i adjust stem length and height depending on my fitness at the time. a little less bendy after a few weeks in winter, i might use a shorter, taller stem for a bit.

I am with you on big gears and low cadence. (I was raised in the 100 RPM school.) Also, I have to say I don't get why we would want MORE hamstring involvement i.e., sitting further back. Further back = less quadriceps at the top of the stroke right? (Guys can do huge numbers on seated leg press and squat which uses quadriceps and hips but nobody does more than 100 pounds in a hamstring curl.) I feel more powerful directly over the cranks but then I'm a track rider from way back.

KOPS is not about fit, it's about weight distribution and body orientation. Fit is about leg extension and hip angle, neither of which are related to KOPS. Where KOPS comes in is in setting saddle setback and handlebar height. For your average built average road racing cyclist, KOPS gives you a rule of thumb that makes for a good tradeoff between handling, power generation, and aerodynamics. It makes for kind of a neutral, flatland road racer position.

Different fits for different uses. For example:

• My sprint track bike has very low bars and the saddle is pretty far forward; my knee is a little forward of my pedal spindle. It means I support more weight on my arms and the front wheel carries more load; this affects the handling, but I want the aerodynamics and the power generation of a closed hip angle.
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• Time trialists are similar except they want their saddles a little further forward to open the hip a bit more. Triathletes are an extreme example because they want the bars low and a very open hip (so they don't fatigue the running muscles), meaning their saddles are even further forward and they have even more weight on the bars.
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• Climbing specialists and recreational cyclists tend to want their weight back and their hips open, so their knees are likely to be behind the pedal spindle.

Well stated.

So, are you in front or behind KOPS? Or maybe you are exactly at KOPS because you have no clue?

Thanks Brian. That explanation makes sense but of course KOPS is often set forth as being precisely about fit. The human leg & foot connected to a crank is basically 4 separate moment arms of different lengths acting in a circle - slightly complicated. KOPS has been presented for years like some optimal answer to that mechanical calculus rather than simple body position. I'm interested in optimal leverage etc...the geeky part. Not sure how old you are but when I was racing 25 years ago, we were cutting lawns for entry fees and gas. I couldn't be concerned with esoteric stuff but it's interesting now. I have tried to get all my bikes to have the same position but the hips-relative-to-BB is tougher. Anyway thanks for the thoughts.

Kops for many is an appropriate rule of thumb to generate a departure point.

Don't read anything, fit your bike and shoes how it feels best as long as you know the adjustments and how to tweak them. Reading anything about fit guidlines can be such a waste of time and can result in questioning your best judgement. IMHO.

MAy I say it is refreshing to read an actual post with real usuable information.

Thank you. They are few and far between.

KOPS is a starting point.

Well, I moved my seat back last night (from a nominal KOPS position) after reading this thread. In my case it's to try to mitigate hand numbness; moving it back seemed to put my torso in a more balanced position. Less weight on my hands.

We'll see how it feels on today's ride. Really, my knees have been my primary concern; I've ramped up very steeply this summer and pushed through some knee irritation in the process. My fit tweaks so far have mostly been with that in mind.

Will report back what I feel. My seat is now as far back as she'll go. Then again, I'm a very tall lanky fellow.

glad I waited... BUTT, BUTT, BUTT, Brian you didn;t say anything about crit ratz (track rat with road rash...)...
just kiddin...

wow, been a long time since KOPS last paid a visit... so itz time for bar thru axle...

Ratliff sums it up pretty well. Its a good starting point. I use the KOPS method...because well...that's actually where my body eventually settles. Sliding the saddle back...hurts my lower back.

The other explanations about not using KOPS is more confusing than helpful.

Guimard likely was moving the saddle back to close the hip angle which activates the hamstrings and the glutes. Remember at that time, bikes were only build a certain way and had relatively high bars compared to modern road bikes. They didn't have the option of dropping the bars to close the hip angle. Open hip angles (high bar + forward saddle, or knee in front of pedal spindle), stress mostly the quads. The more closed your hip angle, the more power you can put into your pedals because you activate three muscle groups instead of one. On the other hand, it is harder to breath and so it somewhat limits your aerobic output.

The trick is to balance these out. Road sprinters and flat lander rolleur types are relatively neutral to closed hip angle. Climbers have an open angle they can then close by sitting on the back of the saddle if they need the power (they get away with this because their torque to the pedals is relatively low during a climb; power riders have to make their upper body super rigid to drive power into the pedals and so have no choice but to sit on the front of the saddle - hence the term "on the rivet"). Where position your body over your bike depends a lot on your strengths and goals for your riding.

KOPS is a starting point. For me and fellow riders I've checked, the most common thing for road bike position is to drop the plumb bob from the bony protrusion on the front of the knee just below the knee cap. From there, mess about until you seem to be developing your best climbing power with your current musculature, assuming a road bike fit. Since there are so many different sorts of bikes and therefore different sorts of fits, I doubt that one fit is more prone to injury than another. And "efficiency" is too loose a term to even enter the discussion. You want power at LT or FTP. That can be measured.

I also think this is a sensible position that provides a good way to start, but can and probably should be adjusted to one's particular anatomy and style over time, as you learn what is comfortable for you. Honestly, I do not put too much weight in these "rule of thumb" positions. Not that they are useless or untrue, but they are just general guidelines to give you a ballpark-correct fit.