I did a little research on the GPS’s. There are lots of models out there, the more features you want, the more they cost. I decided to get a pretty much basic model since it had the features I wanted. Since it was going to be beat around on the DS, I didn’t want to spend a lot on it.

I decided on the Garmin E-Trex. It was in the $100 price range and one of the smaller waterproof units. It works great, it will show direction, current speed, max speed, etc. Just mark a spot you want to remember such as camp or your truck and then you will always know which way you need to go to get back….and how far.

The cheapest place I found online to get it was www.gpscity.com.($109) I was about to order it when I saw an ad at a local sport store for $99, so I got it there.

They make a handlebar mount for it, which I might get sometime. Don’t know that I would always use it since I ride trails as well and I am afraid a tree branch would have it for lunch.

I purchased the Bombardier handle bar bag and keep it in there. (Along with other misc items).

 

Max speed on GPS is approximated speed. I drive down the freeway with one at 70 and my max speed-reads 65 MPH. It all depends on how accurate the GPS is. The best range on my GPS is16 feet and on a straight line that would be a 32 feet gap

 

Agreed. If you happen to be in an area that has weak signals, you might not get an accurate reading. I have used mine in my truck while driving in both city and highway, and it always shows about 1 mph under what my truck is saying. I figure the GPS is more accurate than my trucks speedo…..since it is showing 1 mph under at any speed, I think it is very accurate.

Max speed on my GPS is whatever the maximum speed registered by the GPS. (You can reset this back to zero at any time).

 

How is the GPS unit calculating speed? Is it instantaneous speed or an average over some time interval? How often is the position sampled? Would it give useful speed info during a drag race that lasts just 7-8 seconds? Or would you have to remain at a given speed for a second or two for the speed reading to be accurate? When in your truck does the GPS agree with your speedo during acceleration? Can GPS units record your position, time, speed, etc? Can you link data between a PC and the GPS unit? What kind of memory storage does the GPS unit have?

 

Did you ever change the size of the tires on your vehicle? That can greatly change the speed at which you are driving down the freeway. On my truck with factory tires, my GPS reads 100% concurrent with the speedometer. On my car, which has a slightly smaller tire size than from the factory, it reads about 2MPH slower than the speedometer. I've tested my GPS over a great variety of situations and terrain, everything from city driving to a desert run (250-ish miles) from LA to Vegas, same results anywhere I use it.

 

Scooby, my GPS (not anyone else's) seems to have worked like this for me:
Calculating ground speed is perfect, very little problem here unless you are standing still. It reports speed maybe every 0.5 - 1 second I would guess, it would be very useful in a 7-8 second race. A good GPS will give you trip time, trip distance, average speed, top speed, elevation and more stuff that I don't even use. Yes you can link many (not all) GPS's with the PC. The one I bought which I would recommend to others is the Garmin GPS12. (I was going to buy a Magellin, but the Garmin models all had many many more features.) This one will link up to the PC, hold 500 waypoints, and 20 routes, gives you a map of your route, (which you can zoom in and zoom out of as needed.) This one may be waterproof, I don't recall - I keep all of my electronics away from water either way. I have yet to buy the PC software at this point, but maybe someone else reading the forums has and can give us all insight as to how well, or poorly it works. When I bought mine 3+ (I think) years ago, it was selling for $150. This same model, is STILL selling for $150, so I figure it has to be a pretty decent unit if they haven't bothered to replace it with a new model ir even change the price. If nothing else, you may want to use this model as a benchmark when comparing other GPS'.

 

My GPS pretty much is instantaneous in calculating speed. Like BlackHawk said, it is <=1 second. In my truck it pretty much follows the speedo under acceleration by about a second. Yes, mine can connect to a PC. I didn’t buy the cable yet though. Memory? More waypoints than I will ever use.

I guess you are wanting to know top speed in drag racing, this probably isn’t the best device for measuring this. Get an accelerometer. I am looking at the G-Tech Pro. www.gtechpro.com.

 

I have a small Magellean GPS and use it for riding all the time. Speed readings seem VERY accurate....judging by riding in a new vehicle it seems dead on, even with cruise set..mine is very accurate...down to the tenth mile per hour. I guess using up to 12 different sats for tracking helps though. If you can somehow tape that GPS to the bars to where you can see it doing 70+ mph on a quad then you have your speed reading. Don't know about anyone else, but im not taking one finger off the bars at that speed. If you have a Staples near you, they sell them in the computer area. Mine was about $106.

 

If your looking for a GPS for directions and accurate speed readings (no PC interface) the Garmin eTrex can't be beat.

The "GPS Store" has fair prices. (thegpsstore.com)

 

GPS measure speed using doppler shift. They DO NOT measure speed bu measuring distance vs time. A GPS is probably the very most accurate way for the average person to measure speed; better than radar. Radar needs to be calibrated with a tuning fork to calibrate where a GPS gets it's calibration from the cesium standard aboard the satellites.

Sorry, but anybody that says that they are hitting mid 70s in the sand on a stock quad is seriously overestimating their speed. Anybody that says they can measure speed by the feel of the wind or terrain going by is seriously overestimating themselves.