Bike Fitting – Proper Saddle Fore/ Aft positioning

Many peoples idea of where to place their saddle generates from quotes like this one, ” In the proper neutral fore-aft saddle position, with the pedal at 90 degrees (9 O’clock), a plumb line placed at the front edge if the kneecap should fall to the end of the crank arm”, is indeed incorrect bio-mechanically. I have seen this description listed in many an article and mainly from PT’s for some reason. This position would place the riders knee from 2-5 cm past the ball of the foot depending on cleat position, length of crank arm, etc. This is a poor position for delivering efficient power to the pedal, but is very good for generating knee strain, Vastus Medialis soreness and hot spots in the foot.

From the neutral position the plumb line should generate from the tibial tuberosity (the bump below the knee cap) and fall at or just behind the ball of the foot. This position greatly reduces the strain on the patellar tendon during the downstroke specifically when the most force is being generated. Having the seat too far back straightens the leg too much and generates the same problems as having the seat too high. From the neutral position (once found) you can very slightly tweak the seat position forward or back depending on whether you are a high cadence spinner or a big ring masher.

Of course there is also the discussion of knee angle that needs to be addressed in the position. Once a neutral for aft position is achieved then you can work on the knee angle. This process may go back and forth a couple of times to find the correct combination for your body. In a nutshell a higher seat (smaller angle) transmits more power, while a lower seat (larger angle) conserves more muscle energy. The seat height of course also affects the biomechanics of the knee itself. The more you bend your knee the greater the stress placed upon the patellar tendon, if the seat is too high then the strain goes to the iliotibial band. Assessment – you feel pain in the front of the knee – raise the seat slightly. You feel tightness or pain in the back or side of the thigh – lower your seat. If you have a functional discrepancy causing the knees to be two different angles that is where shims can help.

To properly assess these structures in the dynamic environment of pedaling it is advisable too have a professional bike fit expert work you through the process and make changes based on trained objective experience. A proper bike fit can make one of the most significant changes in your bike times.

———-
Coach Phil Casanta,
Bike Fit Specialist, Hypercat, Inc.

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