This past week training indoors my PT SL+ showed a 529 torque offset value on the Garmin 800 as I would use the "calibrate" button just before training. Even at the end of the intervals I would try to calibrate again, but still would have the 529. This particular hub has always shown a little to the high side and most of the time the value would be around 518 to 520.
Training indoors on the rollers and seeing the usual metrics, like cadence and speed, would be about the same as I would hold for a 91% of FT type effort, but the power output numbers were low. Just about killed myself try to raise my effort to hit the goal and thought it was either the high value of the 529 and/or a good bit of fatigue from some previous hard efforts.
But this morning before my 80 mile route it calibrated with an offset value of 526. I am very familiar with the route as I use it most Saturday's so I have a good idea of using RPE and can typically end up with the IF/TSS that I try to hit. This morning's ride ended up at 0.67 IF / 214 TSS. I would have guessed it felt more like 0.75 IF / 240 TSS based on many previous rides with similar traffic and weather conditions. Both cars and wind were not really a factor. I usually do this as a lower intensity ride, but I think this ended up a little lower than it was supposed to be data wise. Fatigue wise the legs are a bit sore and I worn out so it felt more than 0.67 IF.
So I did a quick and rough weighted torque test and think it may be out just a little. Like 3%.
Not sure what to do next since the error is not horrible, but when someone is trying to hit those levels of 91 to 95% L4 during the week it is kind of frustrating. The hub is one month out of warranty as one could figure. I don't seem to have great luck with Powertap hubs. ARGH! Finicky and fragile little creatures
Here is my rough test done just a few minutes ago.
Here are the metrics to the ride this morning if that is of any use. (contains one of my favorite new quotes from Dave in the ride description )
So it may not be out too much accuracy wise. What would you do?
Saris is going to be the standard $350 regardless
Wheelbuilder I will check with them since I think they are allowed to service PT hubs and I had them build the wheel.