# XERT Metrics as a function of %slope

To what extent will my powerXERT power output metrics change as a function of riding all my workouts at a 4% positive slope? I ask that because of a serendipitous discovery that on my KickR bike smart bike, when the slope on the bike is set to 0%, despite having my fit to the bike professionally measured out, the forward rocking motion associated with adding power output causes me to slide forward on the seat requiring continued readjustment of my seating position. When I elevate the slope to 4%, I no longer experience any rocking forward and aft (presumably Wahoo figured that effect emulated being on the road - sic). Hence, I no longer slide forward out of my calculated seat position and do not have to readjust it. However, I don’t know how that affects Fitness Signature calculations, or any other metrics, or even if it does have any such effect(s). It sure does feel more effortful, but it sure as heck is nice not to be sliding forward on my seat. Any thoughts?

anthony

I don’t think it should have any effect on metrics as it is similar to using a riser block with a trainer that many claim relieves saddle pressure that occurs while riding indoors in a fixed seated position for so long.
Does 4% work out to be about a 4 cm rise?
Sounds like you could also resolve the issue by modifying the default position on the smart bike even if the numbers don’t match your outdoor bike.
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Hi ridgerider2, good question! At the seat tip, using a rigid plate resting on the seat, I just measured the difference in elevation as 1/4" higher at 4% relative to 0%, or .635cm. At the same position, but using angle of declination, at 0, the angle of declination at the seat tip is -4 degrees; and at 4%, the angle of declination is -2 degrees. The ProFit metric, calculated using the Trek professional fitting protocol as seen on the Wahoo Kickr Smart Bike’s settings page, is -3 degrees. I’d say the variation is measurement error and likely inconsequential as to my sliding forward and backward as the bike rocks for and aft under pedal pressure. So, output fitness metrics are likely inconsequentially affected.

I’m not at all skilled as to measurement acquisition, so the variation could equally be likely attributable to my incompetence in that regard, as well as my conclusions about any impact on Xert’s fitness metrics. Since the ProFit assessment incorporates the leg length imbalance between L/R, and, as well considering the historical structural injuries to my R leg/hip system, my pedaling continuity and symmetry is likely the major culprit.

I’d appreciate your thoughts as well. Thank you for responding, Anthony