This thread has got me thinking. I’m now sure the Zspider on my TT bike is under reading, I did a ramp test on Tuesday (in the TT position) and got an FTP of 286w. I haven’t been training properly for a few weeks but was still surprised by the drop, I’ve been using an FTP of 323w for most of the summer which felt about right.
So went for an outdoor ride this morning and did 1hr 30m at 297NP on my road bike fitted with a 2nd Zspider, so the FTP is defo too low. I re-calibrated when I got home and got a torque offset of -255, I’ll do the TT bike tonight.
I’ve had a quick look on the website and they recommend you submit a fit file and the data saved through the app if you think the power is out. I was also thinking of doing a couple of 10 min efforts at 250w with the Kicker connected to TR and the TT PM then road bike PM connected to my Wahoo. This should give a set of numbers to compare.
I guess I then have the choice to either adjust the offset in the app or send it back for re-calibration.
Anyone got any similar experience? What steps did you take?