Online Question: "When fitting clients, what do you find the correlation is of saddle height and leg extension (at max)?"

Marc,

This is a great question and I would say drop it 2mm (about the width of a sharpie marker), but I urge you to look at it from another viewpoint. Instead of driving to a desired knee angle that is merely in the range, think of the knee angle as the end result of the pattern and angle of the foot at the top and bottom of the stroke after cleat placement, canting, and internal shoe support. We also have to consider the front to back (fore/aft) as the relationship between the knee over (plus or minus) the foot can affect timing as well as knee health. You have to think of the femur as a lever similar to a locomotive with the foot acting as a concentric in the connection. My clients are all put through a thorough flexibility and structural exam so I know ahead of time exactly what the limitations are, and you will definitely need to know the profile of the lower back and sacrum of that individual. 

Seat height can vary and be environmental.  Houston (Gulf Coast/flat) clients left to their own accord tend to gravitate towards an up and back position to make use of full extension of the leg from a position that is above and behind the pedal spindle. In most cases the knee angles will be high with the feet slightly toe down.  This footpath tends to resemble the shape of a vertical watermelon, where the emphasis is vertical extension into the stroke (think locomotive) and pulling up, with very little torque through the bottom half of the stroke. Main complaints are usually lower back and saddle issues. Austin (Hill Country) clients on the other hand tend to run slightly lower and forward since the need to have the foot in full contact through the bottom of the stroke with a slightly forward bias due to more climbing. Knees angles are usually lower here, but dependent if the client dorsiflexes pulling the foot flat through the bottom of the stroke.  The foot tracing here looks like a fat egg since the lower and forward saddle produces more torque through the bottom. Common issues are lower back, quads and hands since most folks are too short in their reach after moving the saddle forward to place the knee farther over the foot.

 In either case the knee angles will vary depending on the individual and their conditions but it is most important to listen to cues of what they want and where they feel that they need it most. You are just choosing different sides of the range depending on the goals of that person. The casual rider with an emphasis on comfort may want to be back and down to change the weight distribution to relieve pressure off their hands and the saddle interface is paramount. More performance oriented individuals may tend to trend on the higher side as weight distribution leans towards the front end more and even more so for triathlon. Hope all is well in Florida.  Enjoy the ride. 

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