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Powertap SL+ Hub - Service?

post #1 of 2
Thread Starter 

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.

http://thecyclingaddiction.blogspot.com/2012/10/2012-10-6-powertap-sl-static-torque-test.html

 

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 smile.gif)

http://thecyclingaddiction.blogspot.com/2012/10/brewery-to-cagle-road.html

 

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.

post #2 of 2
Thread Starter 

Never mind redface.gif

 

I checked this morning and the torque offset value dropped to 525.

 

I wasn't sure what the upper acceptable value was, but on one forum it said as high as 524 on the upper end of the range. With it being 529 all last week was not too far out of range and the static test kind of confirmed this as being between 3% to 5%. Again mine has always been higher than the 512 value even as brand new with most of the time around 518 or 520.

 

Also saw one discussion on possible moisture with the hubs that have the carbon windows. The last several weeks I was in rain for a lot of hours on my Saturday training rides. The discussion was to remove the hub cap and let it dry out if it does indeed have moisture that seeped through the carbon windows. It seemed dry when I changed the batteries the other day, but I will try that after today's ride just in case.

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