Knees like pistons!

So I have Been having some fit woes as I hit 5th decade of training. All on my right leg. Got a professional fit done. He didn’t really track my knees. There was a lot wrong with my fit, in fairness. When I got the final numbers he set they were pretty much the same as my original fit before I messed it about trying to fix my knees. As part of a general frustration I decided to go smart trainer and TR early this year. Boy have I been training wrong. Anyway long story short. The knee tracking optionals: what is being asked for here? Tracking your knees vertically OR tracking your whole lower leg vertically( i.e. keeping KOP). I have always read it as KOP. This has always resulted in leg discomfort and pressure on the outside of the sole. During the session this morning I went from the later to the former and for me anyway let my knees come in closer to the top tube but still track vertically, just not KOP anymore? Revelation on comfort for me. Just wondering am I just knock kneed and need to go with it or force em out. I suppose I am pretty much answering my question implicitly but gotta wonder about the community experience of this.

Confusing post because KOPS is a fore/aft reference as seen from the side. Knee tracking is oriented (all I’ve ever seen) looking at the rider from the front. Ideally as you push down the knee neither tracks towards the inside or outside. Where the knee falls (left to right across the pedal) depends on you (tight IT band etc…) and how you have your cleats positioned re Q-Factor.

Just a WAG maybe your cleats need an adjustment towards the outside of the shoe. Honestly I’d go back to the fitter and discuss it rather than getting advise from unqualified yahoos like me.:wink:



  1. KOPS (Knee Over Pedal Spindle) is about Fore-Aft position of the saddle, that sets the knee position in relation to the pedal spindle when the crank is level with the forward foot.

  2. The “Knees Like Pistons” is about the Left-Right tracking of the knee during the pedal circle. Generally, you want this to move up and down with minimal Left-Right, side-to-side movement.

    • Everyone is different and a fitter should be looking at many factors when doing a fit. That’s because the knees in, knees out, or any variation is not perfect and prescribed for everyone. Our natural body alignment must be reviewed and addressed accordingly. When done right, this is one step to prevent pain or injury to the knees.

(I am a fitter and deal with this in every fit we do).


Yeah in fairness KOP was a poor way of expressing it. I am revisiting the fitter alright. I am just interested in how others might be reading that exercise as I had a bit of a doh! moment when I let the knees drift in and felt much more comfortable doing the exercise. My cleats are set to minimize my effective Q factor ( if you follow me, another dodgy label). We did this and reduced the bar width as the fitter noted I was too narrow for my setup.


The idea of the drill in the workouts is to work on proper form, to create good pedaling habits. Wobbling knees are generally to be avoided. But some lateral movement is possible and even necessary for some people, and should NOT be forced into direct, linear movement.

It’s all about trying to form good motion control and minimize wasted movement the can be energy loss, or an opening to injury.

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