I developed a knee injury from training all winter on a non-pro-fitted cervelo p3 and the fitter at the LBS is thinking about slipping the saddle around to the “road” position so I can drive more with my big legs (200 lb-er therefore, big quads). Also, Just the way I fit on the p3, I need to shift my body back so my knees don’t get the same injury again.
Any thoughts on this? Won’t this jeopardize the entire theory behind the tri seatpost angle?
Ah yes, the “more power from a slack seattube” argument. Go to a different fitter.
Going slacker will not allow you to apply more power. Kraig Willett did a study that shows that power application is basically independent of seattube angle, measure from 0* - 180* (yes, 180*, with someone facing downward in a harness). Going slacker will close off your hip angle.
The myth of slacker = more power comes from riders sliding back on the seat when climbing to generate more power. There is a whole lot more going on there than just changing seattube angles.
Go see a good FIST qualified fitter in your area. You need someone who understand what caused the knee injury in the first place (seat too high/too low/etc.), and then have them fit you properly.
Going slacker on the seattube is not necessarily wrong, but it sounds like your LBS fitter is just another cyclist stuck behind the times with old-school myths about fitting.
Great reply Rappstar.
Yeah, what he said 