GPS: Tool or Toy?

[Marty Hill]

I've gone about 180k miles behind a gps. I can remember 3 or 4 times it tried to lead me wrong. Not bad odds. Nothing dangerous, just told me to turn left when there wasn't a road and things like that. I just laughed at the POS and kept riding. I have lots of friends using them in planes so I assume they are fairly accurate.

[David]

I have lots of friends using them in planes so I assume they are fairly accurate.

 

If they're using a GPS that is not certified for flight, they aren't any more accurate than the ones you and I use on the ground. Ones certified for flight (essentially for approaches) are a heck of a lot more accurate because they use "differential GPS' signals (a ground station at the approach end of an ILS knows its own position, calculates the error in the reported position, and broadcasts that to the airplane so that the error factor can be accounted for). But a certified GPS is a whole lot more reliable--and expensive.

 

But in real life, I've found uncertified GPS units to be very accurate about position--it's the underlying basemaps that are screwed up.

[Mike]

 

But in real life, I've found uncertified GPS units to be very accurate about position--it's the underlying basemaps that are screwed up.

 

Right. What started us down this particular segue was a statement about using the GPS to predict upcoming road conditions. I agree with Russell that it's a mistake to rely on a GPS as a predictor of the next turn. They're pretty good--though far from 100% accurate--at telling you generally what lies ahead. Sometimes the map data is way out of date and/or just plain wrong.

 

I find a GPS to be a valuable tool for a lot of the short rides I go on within a 100 - 200 mile radius. I can ride without regard to where I'm going, then just check the map to get my bearings and/or punch in a destination once my freestyling time us up. A GPS is a great supplement to paper maps, but for general route planning, I find real maps a much better tool.

[russell_bynum]

But in real life, I've found uncertified GPS units to be very accurate about position--it's the underlying basemaps that are screwed up.

 

Exactly.

[trif]

One of the great benefits to GPS is it's ability to tell me when not to turn. Say you're rolling down the street and you're made aware of a turn coming up (either by glancing at the screen or by voice). If the magic box says turn in 0.2 miles, and I visually estimate the next street up as about 200 feet away, then I'm sure (or as gadget-sure as I can be) that the next street is not my turn. That frees me from looking for a street sign to get my bearings and allows me to enter the intersection watching for threats to my safety.

 

Can it be a distraction? Sure. If you roll through that intersection pushing buttons or fixating on the GPS screen, it may get you hurt. Just don't use it that way.

 

Of course, GPS is not 100% reliable. As has been pointed out, the digital maps are much weaker than the satellites and processors. But on an every day basis for road use, it's good to within about 12 feet of accuracy.

 

Very cool toy, but also a tool that makes my riding safer.