odd behavior--fog or aliens?

[R Mc]

Did a stage race this past weekend. Both of the a.m. road stages started in heavy fog (but Saturday was much worse than Sunday).

I've ridden with the iBike in fog before and had no problems. During Saturday's ride I had a couple of problems surface. One set of really peculiar wattage spikes (3989w whilst cruising at 15mph . . .) was caused, I'm fairly certain, by a low battery.

The other seems, in hindsight, to have been partially caused by fog collecting in the wind port. Whatever the cause, for the rest of the day, the wind offset wasn't working (i.e. it would read wacky #s like 59mph, I'd hit offset and it would go up to 98mph--and I was out of the wind . . .).

I'm attaching the Saturday morning file. The high vibration sections that appear if you analyze power seem to be voltage induced rather than road induced because while the road was rough, it wasn't bad enough to cause drop outs in most circumstances.

That seemed better yesterday . . . but somewhere in the first miles of the race my magnet spun out towards the rim away from the sensor, so I have no data for what was a screamin' fast race.

(I also heard a rumor that lots of users of ant+sport devices (quark, srm wireless, ptaps) had trouble getting data on Saturday morning.

[coachboyd]

A low battery can also cause the wind offset not to properly zero. I experienced this a few weeks ago, and after I changed the battery it worked fine. I had the same issue you did. I would do the wind offset and it wouldn't go anywhere near zero.

[R Mc]

it was still not off-setting properly after I changed the battery . . .

[Robert]

I was in Fayetteville this weekend as well. I didn't have any obvious issues with my iBike, but did have some interesting numbers for Saturday. I was able to hide in the pack the entire race without doing any work. Just followed wheels and never had to close any gaps, possibly one of my most efficient races ever. When I downloaded the ride, my average watts were 105.6! I didn't think I was that efficient! Normalized power was 181 I believe, still pretty low. I'll attach my file.....

[R Mc]

The unit seems to be fine, and I'm inclined to think that low voltage is the primary culprit, since the numbers up to around an hour in look right and then they just tank completely.

There was condensation on the underside of the display screen after Sunday's race, though, so I can't completely rule moisture out either..

(Sunday's race was tanked by a different sort of gremlin: I re-did tilt and offset (which worked fine on Sunday), and warmed up and things were fine. Staged for the race, rolled out through the short neutral section--which in the 40+ race wasn't all that neutral. And somewhere after the first accelerations, the speed reading disappeared. Cadence and hr were still there, but no speed. Afterwards, I learned that we stayed at or above 30mph until the hot spot hill . . . and there I was, wiping the fog off of my rx sunglasses, and scrolling through the set up screens to make sure that the speed was set right. It was set correctly, but I figured out after the race that the magnet was just loose enough to get flung further towards the rim . . .)

[mullerrj]

I'd DEFINITELY put some loctite around the screw/threads of the speed sensor magnet to keep it from sliding. I could see even before I put mine on my spoke that it was going to slide one day. Actually, I used silicone sealant adhesive on mine to not only act as loctite on the threads but to also hold it to the spoke. So far, so good, and I've ridden over 500 miles with it. Give it a try! Rob