General Cycling Discussion - Why did my computer flip out?

All of a sudden yesterday my cycle computer decided to flip out and register approximately twice the likely speed. About 1/4 of the way into our 50 miler (after averaging about 9-10 mph in very muddy, wet conditions) it was reading 19 to 20 mph and even higher, needless to say the miles ticked away at about twice the rate they should have too. The display isn't faded nor is the a low-battery indicator flashing. Is there any reason it would have suddenly come out of calibration? Or, is it more likely that the battery is dying? Both sensors seem fine and it's always been weatherproof and reliable. It's and Echo F1 that's about 3+ years old.

If you were riding in wet and muddy conditions, you could have gotten some water, mud or grime between the contacts. Try cleaning them off. If that doesn't work, it could still be a battery issue. But, hey, on the bright side, maybe you really were going that fast. ;)

I'd really like to think that I was riding that fast-it would be a boost to my ego, but unfortunately I don't think that was the case :(

If all other function, excluding speed, work well as suppose to, it's not likely to be a computer itself.
Yeah, would be nice to check the sensors, and if there are still any doubts left, another cyclist with computer could roll beside you and tell his readings... to compare...

A couple of months ago my computer irrationally decided to clock 95km/h on a ride one day. There's no way I was going anywhere near that speed. It only did it the once, and there was no rain involved (unfortunately).

It didn't somehow switch from mph to kph, perhaps...? That would do it :) If it's still misbehaving, try adjusting the relative positions of the wheel magnet and the sensor.

Were you riding near any source of radiomagnetic waves, such as high tension lines etc?

Originally posted by Chris L
A couple of months ago my computer irrationally decided to clock 95km/h on a ride one day. There's no way I was going anywhere near that speed. It only did it the once, and there was no rain involved (unfortunately).

That can happen if you ride over a traffic sensor...

http://www.neebu.net/~khuon/gallery/visual_tao_of_cycling/FlightyDeck

Whenever it gets wet out (even damp) my computer goes nuts. I tried everything to fix it. The only thing that works is on a damp or wet day I cut a clear plastic sandwich bag and tape it over the computer and around the handlebars.

Next time I have extra $ I'm going to get a new computer.

I think mechBgon is onto it. I checked yesterday and the fork-mounted sensor (not the one on the wheel) seems to have been jarred loose. I re-aligned it and everything was fine on my ride into work this morning. Thing is that the sensor mounts via zip tie around the fork. As this was on another bike, it had to be cut off and rigged to the current bike. I used several zip ties but I guess the constant bumping of the C&O Canal was a little too much and it slid out of position (something it had not done on road). I'm thinking about using super glue to mount it more solidly. Any ideas?

I wouldn't go with glue on the frame. A little two-sided tape, or even some non-slip rubber between the sensor and the frame should be all that is needed to help the zip-ties hold it in place.

I have had the same thing happen to me. I traced it to moisture (not rain) getting on the contacts between the mounting bracket and the computer. Once I realized what it was I wiped the contacts down before every ride. I have not had this problem since doing this.