PowerTap SL cold sensitivity?

kmavm

First of all: thanks to everyone for holding my hand through those jittery first few weeks of PowerTap ownership. Since January 1st, the unit has been flawless.

Until this morning, when I went out for a chilly pre-dawn ride. Everything was fine for the first 3 miles or so, and then the hub just went on vacation. For the rest of the hour, the CPU never picked up a single sample from the hub. Wired cadence and heart rate remained fine. After I got to work, I let the bike warm up indoors for an hour or so, and the hub seems perfectly happy now.

I've heard about the PowerTaps being sensitive to cold; is this what happened to me? I'm a little skeptical, because we're talking about northern California, here. It was the high 30's Farenheit at the coldest, and probably more like the low 40's. However, nothing else was out of the ordinary about the ride. Thoughts?

palewin

Its not the PT, its the batteries. The point at which the batteries fail to provide sufficient juice is variable, since it depends on how old the batteries are (new batteries handle cold better than used batteries). If you speak with Saris, they predict problems starting around 30F or so. My own experience is that with relatively fresh batteries I'm ok down to around 22-25F, and below those temps both the batteries and I tend to fail. My guess is that with new batteries and the temperatures you mention, you would be fine.

kmavm

Hmm. These batteries are less than 1 month old; I had to replace the ones that came with the unit. I haven't quite gotten in the "250 - 300 hours" of riding in this month that the powertap manual suggests I expect . Is it possible my hub is tearing through batteries especially quickly? I'm also not seeing the "flashing transmission icon" that warned me of fritzy batteries back in December...

Also, I did a two hour ride in the warm early afternoon sun, and the powertap didn't miss a beat.