GPS question

39 replies to this topic
  • jj

Posted May 08, 2000 - 06:46 PM


Hey all!

I was wondering if you guys could help me get started here. I'm looking at the GPS III+ and am wondering what else I should I should get. I want to map and name and print all my trials as accurately as possible.

Let me have it, dont leave anything out. It aint gonna be cheap but whoever dies with the most toys...

If you know of a good place to buy this tuff cheaper please post.

  • Ron_in_SoCal

Posted May 10, 2000 - 09:43 PM


Three years ago my girlfriend gave me a Garmin GPSII to "strap to your motorcycle and map your trails". Pretty cool, 'eh? (Yeah, she's still around) :)

The reason I bring this up is because I've been down this GPS road a few times now, and have made some expensive mistakes along the way. Here's what I've found to work best for me:

Put the receiver in a padded camera bag with a zipper for protection and put it in a good backpack. You will need an external antenna to do this. I used velcro tabs to secure the antenna to the backpack. It sounds kind of clumsy, but it works great. Another lighter option is to use a camelback less the bladder to hold the receiver in the padded case. I also have modified my riding jacket to have the antenna mounted on my back and the receiver in a pocket for the winter months.

Mounting the thing on the bike caused me to crash a lot while trying to read it while riding (I have the same problem with my enduro computer), and the more I thought about it, who cares what it says anyway. While riding I'm just in data collection mode, gathering a track log of the trails. If I get lost on the trail or find a cool place I want as a waypoint, no big deal, just stop and get a drink of water (also in backpack), get the receiver and do your thing. Back on the trail in no time.

My receiver has logged many brutal off-road miles in rain, heat, dust, mud, and snow and still looks new. Others I know have mounted it on the bike and I've seen a few get smashed or drowned dead in deep water crossings. Ouch! The external antenna is sleek and tough. The only problem I've had with it is at the bnc connection to the receiver. The connector broke after a hard getoff. A little epoxy glue fixed it and now it's stronger than it was before.

Another thing that seems to really improve the accuracy of the unit is to let it acquire a good lock on the satellites before you move it. I normally turn it on and set it on the hood of my truck as soon as I get to my riding area. While I'm unloading the bikes and getting dressed for the trail, the things at work finding out where it is. After about 15 minutes, it's ready to go. If I don't wait long enough the track log jumps around a lot and is not as accurate. The newer units are faster than mine, but give it time to do it's thing.

For those interested, here is the equipment I use and how much $$ it costs (US):

GPS Unit: Garmin GPSII (only 766 tracking points - LAME) $120 three years ago.
Antenna: Garmin Part Number 010-10052-04 about $80
PC interface cable: Garmin Part Number 010-10141-00 about $40
Backpack: MSR Colorado Attack Pak ( $42
Mapping Software: DeLorme 3-D TopoQuads $200 per State!
Padded Camera Bag: about $20 at K-Mart

When shopping for a GPS receiver, remember that you want one that holds a lot of tracking points. The more the better. I need to upgrade soon, and am looking at the new Garmin eTrex unit. I don't know if it can accept an external antenna or how many tracking points it will hold, but I like the size and it's waterproof. If that does not work out, it looks like a GPSIII Plus is in my future.

Good GPS related links:

Hope this helps. Wow, this post got long…

  • jj

Posted May 10, 2000 - 05:51 PM


It does help, thank you very much!

I only need the GPS, cable and the DeLorme software to map, name and print my trails correct?


  • Bryan

Posted May 11, 2000 - 06:07 AM


Hey Ron.
I was going to e-mail you but you don't have an e-mail listed. Bummer.
Thanks for all the GPS info. It's a lot of fun.
I like the idea of putting the unit in a backpack or camelback when mapping trails to protect it. I'm trying to find an external non-amplified antenna for my GPS III+ but so far no luck. This is the only one I've found and it looks too bulky: http://www2.garmin.c...ku=010-10052-04

Last night I put the unit in a padded bag with the antenna sticking out and did one my favorite, although crowded, local mountain bike rides. However when I downloaded the track points into my Topo! software, one of the legs was off by about 300 feet. The route I took was an out and back route and the 'back' leg was off of the 'out' leg by that distance.

Could this be because I was not getting a good signal for a while? I'm hoping an external antenna would help? When I did a ride with it mounted on my handle bars, the out and back overlapped routes where spot on.

By the way, I recorded 680 track log points on my GPS III+ and it only used up 30 percent of it's memory. Plus, if I use up that memory, I can save the track points off, clear the active track log and continue on. It can save up to 10 track log files in addition to maintaining its current track log.


[This message has been edited by Bryan (edited 05-11-2000).]

  • jj

Posted May 11, 2000 - 07:21 AM



I know I've seen an antenna that mounts to the back of the number plate, I just cant remember where I saw it. I looked similar to the antenna that come with the III+ but it was remote...I'll keep looking.


  • Bryan

Posted May 11, 2000 - 07:38 AM


Yes JJ. I've seen that picture too on the A-Loop web site. But, it isn't shown as an accessory on their site or on the Garmin site. I'll probably call Pete at A-loop and get the scoop.

  • jj

Posted May 11, 2000 - 07:45 AM


Actually one of your other posts about aloop just reminded me that that was where I had seen it.

Please let me know what you find out...


  • Ron_in_SoCal

Posted May 11, 2000 - 07:52 AM


The antenna is from A-Loop. It wants the GPS receiver mounted on the handlebars. ( ) This antenna should work in a backpack as well. I'm concerned about using up the batteries too fast with this antenna.

Bryan, the problem you described is defiantly bad reception. I had the same thing happen. The external antenna fixed it right up. The antenna you are looking at (Garmin Part Number 010-10052-04) is the same one I am using. When I first got it I was a little disappointed, the wire is real long and thin, but this turned out to be a good thing. Just bunch it up with a rubberband and adjust length to fit. It works great.

I looked into the new Garmin eTrex unit I mentioned in the previous post, and it does not take an external antenna. Bummer.

JJ, Don't forget the external antenna! Sounds to me like your on the right track (pun intended). Good luck.

Oh yeah, my e-mail address is

I will put it in my profile for future reference…

  • Bryan

Posted May 11, 2000 - 07:59 AM


Ron, that antenna looks like a computer mouse. How do you mount it? Does it have to be flat? Does it have a clip attached?
It isn't amplified is it? I don't think I need an amplified one since this unit seems to have pretty good reception. It even works inside in my house!

  • Ron_in_SoCal

Posted May 11, 2000 - 08:11 AM


It does look like a mouse. I just used velcro (sp?) tabs to mount it. It comes with a fake mount bracket with suction cups to mount in your car window. That landed in the trash right away. I have found that the velcro keeps it in place without any problems. The velcro tabs have strong two sided tape, and I found them at the grocery store of all places. Box of like 20 for $2, used two in the backpack / antenna connection, two for the camelback deal, and two for the jacket.

I should take a picture of how I've got it mounted. I'll do that tonight.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Bryan

Posted May 11, 2000 - 09:47 PM


I found out more external antenna information.

The picture on the A-Loop site of the remote antenna attached to the number plate is the stock GPS III+ removable antenna with a coax cable you can buy for about 25 bucks attached. Of course it is not amplified.

The other unit, Garmin Part Number 010-10052-04, is a remote amplified antenna and sells for 99 bucks


  • Ron_in_SoCal

Posted May 11, 2000 - 01:33 PM


Same thing at:

for only $69.95US

  • James_Dean

Posted May 11, 2000 - 08:59 PM


Guys, My GPS45 has a detachable antenna unamplified and I use a coaxial cable purchased at radio shack. It was cut to a desired length and a new end attached. The antenna goes through my goggle strap by the adjustment clip (keeps it in place). It looks odd on the helmet but gets a good consistent signal even in the trees.

  • jj

Posted May 12, 2000 - 07:49 AM


So what is the consensus, do we need the amplified antenna?

Bryan you said that the antenna we where thinking of was just the orginal antenna attached via a cord. Will that really make any difference over just leaving it attached to the unit?

Ron, that price for the amplified antenna you posted from GPS sure seemed cheap $69 is that really the same mouse amplified style I've seen everywhere else?

Thanks guys!

JJ in WA

  • Ron_in_SoCal

Posted May 12, 2000 - 07:52 AM


To those who are interested in the backpack set-up I've been writing about, I've just added a link to that illustrates my external antenna connection to the backpack. I tried to do this earlier, but was waylaid…


  • Ron_in_SoCal

Posted May 12, 2000 - 09:10 PM



It is the same antenna. It pays to shop on the internet. I've found things at huge price reductions in the past by just spending a few minutes searching on part numbers.

The amplified antenna mentioned (the mouse one) works great on wooded trails. Stronger signal equals better accuracy. Just my opinion.

  • Bryan

Posted May 12, 2000 - 07:16 PM


I bought the coax attachment for my removable GPS III+ antenna just like James Dean described. I attached the antenna to the top of my camelback with a zip tie, ran the cable down the camelback and put the unit in a fanny pack (in front of me). This gave me quick access to the fanny pack (needed the GPS to see where the hell we were). The non-amplified antenna worked great so I don't know that I need an amplified one. But, I'm riding high in the sky here in Colorado. I'm REAL close to those satallites. I think I saw today one while riding :)
I really would like to mount the unit on my handle bar so I can see it all the time. I bought a handle bar mount. But, I'm afraid to put it there. One crash and that baby is toast.
I could have used it on the bar today to figure out how to get back to the truck without having to stop and look several times.

  • Matt_Porritt

Posted May 12, 2000 - 11:07 PM


I'm REALLY keen on this GPS/antenna idea.
Anyone know if any other mas have been done for anywhere but the US?
I'm looking for some for New Zealand?

Anyone able to help me out??


**Ride it like you Stole it!**
Matt Porritt
99 YZ400F
Rubber Chicken Racing

  • Bruce_in_Phoenix

Posted May 14, 2000 - 08:47 PM


Check this out. You may or may not know that there has been some built in margin of error in the GPS sattelite system. My uncle told me that the government just deregulated the GPS satellite system as of May 3, 2000. It is supposed to now be nearly ten times more accurate than May 2. I can get an indicated accuracy to within 9 feet on my GPS III+.

Can anyone shed any more information on this subject.

  • Bryan

Posted May 15, 2000 - 05:48 AM


Yes Bruce, that is true. 5/2/2000 the pres (Billy Bob) had that done. That's what made me go out and get a GPS III+.

SLick Willy is throwing us a bone before he closed down all of our trails.



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