Yes, the majority of my posts are made from work and I did make that image at work, back in '05. Luckily, I'm a graphic artist, so nobody blinks at artsy stuff on my screen .

I've got a computer on each of my bikes. It's nice to know my speed, as well as the lifetime mileage of each bike.

I checked my Cateye computer by riding on a marked trail. It indicated 101% of the marked distance.

Unless the trail was surveyed and marked, trail markers are done via a bicycle or a hand walked device with a wheel and magnet like your bike. Your bike computer could be right and the trail off by a percent

You have to calibrate with your wheel's circumference anyway, so if you don't do that, you know it's off by a bit. And for best accuracy, roll with YOU on the bike, because your wheel diameter changes slightly when you apply your weight to the bike.

Well, given that the on-screen error indication doubles (like, goes from 12 feet to 25 feet) when I'm just walking around, until I stand still for a few seconds, I figured it was worth thinking about.

It also matters a lot what the weather and sky visibility is. On a clear day in the country, you can get 8 foot accuracy while moving. On a day with weather systems on the move, it can go to 15 to 20 feet. With cover from either trees or buildings, sometimes I'm lucky to get 30 feet. On bad days, I can stand in one place and my icon will move around 50 feet as long as I stand there. I bet I could register 10 miles of travel on those days with the GPS sitting on a park bench.