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Discussion Starter · #1 ·
No doubt this has come up before, but searching the archives didn't
turn up anything. I've been offered a GPS for Christmas but don't have
much idea what to ask for.

I ride primarily in Northern CA in the canyons, with some tree cover
but generally not thick woods, lots of steep elevation changes,
switchbacks, etc.; I live/ride out in the boonies (Sierra foothills), so
street mapping isn't much use to me; I don't need a color display; I
have been known to ride for up to 12 hours, so battery life is important;
I'd like to keep the price to "around not more than $250".

From what I have been able to find out, I'm currently leaning towards
the Garmin eTrex Summit because it seemed like it was one of the
better units when it came to mapping elevation changes. Most of the
reports I read were several years old, though, so the information may
be out of date and there may be newer models out there?

One thing of concern came from a 2001 (?) report I read that said that
the Summit's small size meant that it was less sensitive than some
other GPS units. Is this still true? How well would this GPS (or any
handheld GPS, for that matter) perform in steep, deep canyons, say
like the bottom of the American River or El Dorado Canyon?

One thing that did confuse me was this (from a GPS spec):

* 500/20 waypoint/route storage
* 10,000 trackpoints and 10 saved tracks available

What's the difference between "waypoints" and "trackpoints"?
(I'm guessing "waypoints" are something *you* put in, while
"trackpoints" are something the *GPS* generates to make up
a route/track?)

and what's the difference between "routes" and "tracks"?

And lastly, am I right in saying that if I go with the Summit, I
won't be able to download my rides onto a computer? Do I need
a more expensive unit for that?

Thanks for any advice

LCT
 

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Over the Hill
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I have an older Garmin Legend that serves my uses fine. I do not use it as much as I used to. I take it when I first go into an new area and have found it helpfull finding trailheads. To me it would be useless if I cound not download waypoints, routes, and maps from my computer. Topo mapping software can be more expensive than the unit.

Lots of info on the net, here is one of the better sites.

http://users.cwnet.com/dalede/
 

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I use the Garmin eTrex Vista, and that's been working out well for me ever since I bought the handlebar mount accessory. It is true that the patch antennas of the smaller units are less sensitive than quad-helix antennas, but ever since I employed the handbar mount, the patch antenna is more consistently oriented horizontally (the recommended orientation for optimal reception), and I have had no problems with loss of reception. This was of course not the case when I used to just toss it in my Camelbak or leave it in my shorts pocket.

The Garmin eTrex Summit unit you are looking at is inherently capable of upload/download, but you will need to purchase the data cable and GPS software. The problem is that at that point you will have already purchased the maps that come with the software (I don't believe the upload/download software is available by itself), so it would make better sense to opt for a mapping-capable unit (Vista or Legend), which has the data cable included.

A waypoint is position data that you manually 'mark', and the GPS can orient you to. You mark a waypoint either when you're at that spot, or on the computer in mapping software.

A route is a user-defined sequence of waypoints that define how you can get from one place to another.

A trackpoint is position data that serves as an 'electronic breadcrumb' that the GPS unit marks at intervals to document your exact path taken.

Waypoints and routes are used together in the course of on-the-trail navigation. Trackpoints and the resulting saved tracks can be used on-the-trail to see exactly how you got to where you are, but it is more often downloaded and used as a reference of the actual path of the trail. Aside from the obvious refinement of that data into waypoints and routes, people also use trackpoint data to determine their elapsed times and speeds through parts of the trail.
 

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Wait until after Christmas. Garmin is going to be releasing a LOT of new models in early 04 (including a bike specific model), and the ones I'm aware of include a more sensitive SiRF chip. You could go with one of the new models that's supposed to get better reception, or you could get an older one, whose price will probably go down a little bit.

Bass Pro Shops spilled the beans on a bunch of the new units this past week. They'll be denoted by the "x" at the end of the name, like the Legend Cx, Vista Cx, 60Cx, 60CSx, 76Cx, 76CSx.

FYI, most of the color screen models actually have BETTER battery life than the older B/W screen models. Why that is, I dunno...but it is.

In deep canyons, pretty much any GPS is going to have trouble keeping a signal for very long. I would most certainly wait for the newer models, which should help you out a lot in that regard.

"Routes" (according to Garmin) are a series of waypoints linked together to form a route, so you travel from one point to another.

"Track"/"Tracklog"/"Trackpoint" (according to Garmin) are terms associated with keeping a record of where you're travelling. A track is the path you have taken on a particular trail or road that you can save. The tracklog is the memory that the GPS allocates to saving tracks. A track consists of a series of points recorded at specific intervals (you can change the interval time). These points are called trackpoints.

A route can be created by keeping the GPS off most of the time, and only powering it up long enough to create a new waypoint which you include into a route. A tracklog requires you to leave the GPS on during your travels. IMO, routes are better when dealing with roads (put a waypoint at each turn) while tracks are better for trails or for backcountry hiking/skiing. Leave the GPS on to record track information, and it will also keep track of your speed, distance, and time.

Whichever unit you get, you will want to invest in some software for your pc. The software will allow you to download waypoints, tracks, or routes onto your PC so you can save them and recall them later. The software will also let you transfer information from your pc to your GPS. Not all software transfers the same info, so be aware. Only Garmin's MapSource software will let you transfer base map data (topo, marine, autorouting), but is awful for printing. NG Topo is great for printing, but doesn't let you transfer tracks to your GPS (but will load them from the GPS to display/print). Both will let you do some pre-ride planning.

This topic has been hashed and re-hashed in both Passion and in the General forums. Do some reading, and you'll find good info.
 

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Discussion Starter · #7 ·
NateHawk said:
Wait until after Christmas. Garmin is going to be releasing a LOT of new models in early 04...
"04"? [grin]

...includ[ing] a more sensitive SiRF chip..
which I take means the antenna will be more sensitive?

FYI, most of the color screen models actually have BETTER battery life than the older B/W screen models. Why that is, I dunno...but it is..
good to know. I figured: colour = more expensive, and if I didn't
care about it, it was a way to save money.

In deep canyons, pretty much any GPS is going to have trouble keeping a signal for very long. I would most certainly wait for the newer models, which should help you out a lot in that regard..
it seems scheming, but I could ask the Christmas present
giver to wait... they might go for it.

"Routes" (according to Garmin) are...
got it.

One thing that occurred to me this morning - when the Summit saves
the track, does it also save elevation gain/loss for that track?

This topic has been hashed and re-hashed in both Passion and in the General forums. Do some reading, and you'll find good info.
yuh, I spent some time searching the archives and did pick up some
good info (like patch antennas liking to be horizontal, while helix ones
do better vertical), but I'm on 28.8 dialup, so it takes a while.

Thanks for your help.

LCT
 

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Slghtly OT antenna question

Accessory antennas?

I was out riding a couple months ago and crossed paths with a guy hiking. He was wearing a cameback and had this kinda unique antenna sticking up from his cameback. We stopped to chitchat a little, and he said he was mapping the trail. The trail we were on is under a solid tree canopy, and so I asked him about satellite coverage. He showed me the screen of his gps, which was set to show how many satellites he was picking up, and it was a bunch. Sorry I can't provide more details, but I thought it was interesting.

Anyway, anybody else know or ever see someone using an accessory antenna for a gps, or did I meet the gps uber-geek?
 

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Over the Hill
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HarryCallahan said:
Anyway, anybody else know or ever see someone using an accessory antenna for a gps.
Yes I have one.

If your GPS does not have an input for an external antenna you can use a Battery Powered Re-Radiating (transmitting) Antenna. It takes the three satellites my Garmin Legend and gives me 2-5 more satellites. Link below, ships from Hong Kong so expect a letter from US Customs wondering what kind of electronics you are importing and why.

http://pc-mobile.net/gpsant.htm
 

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elsietee said:
"04"? [grin]
Hey, I posted that late. Early 06.

elsietee said:
which I take means the antenna will be more sensitive?
Yup

elsietee said:
One thing that occurred to me this morning - when the Summit saves
the track, does it also save elevation gain/loss for that track?
No. At best, it will save the actual elevation recorded for that position. HOWEVER, if you display the track in NG topo or other software that displays an elevation profile, it will ignore the saved elevation data and instead display the track over the elevation data within the program itself.

elsietee said:
yuh, I spent some time searching the archives and did pick up some
good info (like patch antennas liking to be horizontal, while helix ones
do better vertical), but I'm on 28.8 dialup, so it takes a while.
Ouch...28.8? I recently ditched my 56k modem for 3mb DSL. MTBR was killer slow on 56k, even.

Yes I have one.

If your GPS does not have an input for an external antenna you can use a Battery Powered Re-Radiating (transmitting) Antenna. It takes the three satellites my Garmin Legend and gives me 2-5 more satellites. Link below, ships from Hong Kong so expect a letter from US Customs wondering what kind of electronics you are importing and why.

http://pc-mobile.net/gpsant.htm
I saw this link posted on the geocaching.com forums. I thought about getting one, but then I hope to upgrade my GPS before too long (I want the 60CSx or 76CSx when they come out), and since Garmin hasn't published any info about the units I want, I'm going to hold off.
 

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Discussion Starter · #11 ·
buying download/map software

DtEW said:
...you will need to purchase the data cable and GPS software. The problem is that at that point you will have already purchased the maps that come with the software (I don't believe the upload/download software is available by itself), so it would make better sense to opt for a mapping-capable unit (Vista or Legend), which has the data cable included.
Hmm, that's kind of sucky. I have access to GIS software (*just* started working with it, hence my ignorance) and all the USGS Topo maps, so wouldn't need to buy any mapping software. But are you saying I wouldn't be able to download anything off the Summit without buying maps?... [grrrr]

LCT
 

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Discussion Starter · #12 ·
NateHawk said:
...No. At best, it will save the actual elevation recorded for that position.
so I can't ride for four hours and then ask it to show me
how much elevation gain/loss I did over that period? (the
same way it'd show me distance/speed/max speed, etc)

Well, what use is that?? [grin]

...HOWEVER, if you display the track in NG topo or other software that displays an elevation profile, it will ignore the saved elevation data and instead display the track over the elevation data within the program itself.
which makes you wonder what's the point of having a (supposedly
more accurate) barometric altimeter thingy...

...Ouch...28.8? I recently ditched my 56k modem for 3mb DSL. MTBR was killer slow on 56k, even.
I can dream. Right now, I can't even get 28.8 - 24 kb is the max... when it rains,
water gets in the lines and then I might as well have mice carrying the data to and fro.

...I saw this link posted on the geocaching.com forums. I thought about getting one, but then I hope to upgrade my GPS before too long (I want the 60CSx or 76CSx when they come out), and since Garmin hasn't published any info about the units I want, I'm going to hold off.
Thanks for that, I'll take a look.

LCT
 

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elsietee said:
so I can't ride for four hours and then ask it to show me
how much elevation gain/loss I did over that period? (the
same way it'd show me distance/speed/max speed, etc)

Well, what use is that?? [grin]
The GPS unit itself will display an elevation profile on its screen, but getting the elevation data the GPS records to display on your home computer will be a trick.

elsietee said:
which makes you wonder what's the point of having a (supposedly
more accurate) barometric altimeter thingy...
It is more accurate (but only when properly calibrated...and it needs to be calibrated often). My Rino 120 does not have a barometric altimeter, and the elevation is displays to me is most likely going to be over 300ft off because it assumes that the earth is a perfect sphere, which it is most certainly not.

Which GIS software do you have access to, BTW? I have ArcView 8.0 and use it when mapping trails. It's a bit over-complicated to use when planning trips and stuff, though, so I have other software for that. Do yourself a favor...get the MN DNR Garmin program (it's freeware) that will take the information on your Summit and allow you to save it as .shp files. Using GIS software, it's a bit easier to actually use the elevations your GPS records at each waypoint or trackpoint.

If you're just learning GIS, I recommend getting the book "Getting to Know ArcGIS desktop". It's a very good book (I think I paid about $60 for it), and even includes a trial copy of ArcGIS desktop you can use with the lessons in the book. I took a class in undergrad that used that book as its basis for the first half of the semester.
 

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Discussion Starter · #14 ·
altimeter calibration/MN DNR/GIS

NateHawk said:
It is more accurate (but only when properly calibrated...and it needs to be calibrated often).
If it's running off barometric pressure, I'm assuming that once
summer sets in and we get our normal high pressure bubble
hovering over Northern CA for months on end, it shouldn't need
calibrating much?

My Rino 120 does not have a barometric altimeter, and the elevation is displays to me is most likely going to be over 300ft off because it assumes that the earth is a perfect sphere, which it is most certainly not.
D'you have to calibrate it? And if so, assuming you do it at the trailhead,
how much difference will it make if you're only travelling in a 10 mile
diameter (assuming, say, a 25 mile loop ride)?

Which GIS software do you have access to, BTW? I have ArcView 8.0 and use it when mapping trails. It's a bit over-complicated to use when planning trips and stuff, though, so I have other software for that.
ArcView 9.

Do yourself a favor...get the MN DNR Garmin program (it's freeware) that will take the information on your Summit and allow you to save it as .shp files. Using GIS software, it's a bit easier to actually use the elevations your GPS records at each waypoint or trackpoint.
ooh, now that is good to know. I wondered what format the data
came off the GPS.

.shp files I can deal with.

If you're just learning GIS, I recommend getting the book "Getting to Know ArcGIS desktop".
I've actually been using it for a year or so, for work - just not in the context
of "downloading GPSed rides to see how far/how much climbing/etc on a
ride one did" [grin]... I use it more for mapping contamination, etc - not nearly
as fun.

LCT
 

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elsietee said:
If it's running off barometric pressure, I'm assuming that once
summer sets in and we get our normal high pressure bubble
hovering over Northern CA for months on end, it shouldn't need
calibrating much?
I have an altimeter watch (Highgear), and I have to calibrate it pretty much every time I start a trip where I want to keep track of altitude. For the best accuracy, you're supposed to calibrate barometric altimeters after every 1,000ft of altitude change and/or after every 6 linear miles traveled. For bike rides, where you'll cover those sorts of altitudes/distances pretty quickly, I think at the beginning of the trip is enough, however, it will most likely not display the same altitude when you return to your vehicle as it did when you left. They're just not that accurate, and b/c of drift due to weather. The new Garmin Edge units auto-calibrate, which should be a great feature.

elsietee said:
D'you have to calibrate it? And if so, assuming you do it at the trailhead,
how much difference will it make if you're only travelling in a 10 mile
diameter (assuming, say, a 25 mile loop ride)?
No, I don't have to calibrate my Rino 120 (pretty similar to the Legend, except with a radio). However, my elevation readings tend to be quite a bit farther from the actual elevation while my watch tends to be much closer once it's been calibrated. This can make a pretty big difference if you want to use that information for generating an elevation profile of your ride. My Rino does not give elevation profiles. I only get elevation profiles from NG Topo software or my watch. Another drawback to the Rino is that if my satellite reception is marginal, it won't be able to calculate my elevation at all, and I never know for sure what the error of the elevation readings really is.

elsietee said:
ooh, now that is good to know. I wondered what format the data
came off the GPS.

.shp files I can deal with.
I believe the Garmin units spit their data out in a .gpx format. The only software that's truly compatable with it is Garmin's Mapsource software. Other programs have difficulty with various aspects of the format, though they're working on improving it. The DNR Garmin program allows you to save your Garmin data as point, line, or polygon types (so you can walk a property line, tell DNR Garmin that the particular track you just walked is a polygon, and display it in ArcView), and it will also let you load .shp line or point files onto your GPS (polygons will just display as tracks, I believe).

elsietee said:
I've actually been using it for a year or so, for work - just not in the context
of "downloading GPSed rides to see how far/how much climbing/etc on a
ride one did" [grin]... I use it more for mapping contamination, etc - not nearly
as fun.

LCT
I'm not sure if you've messed with ArcScene or not, but you can use it with DEMs to make a 3D plot of your ride. I have no idea how (or if you even can) display an elevation profile with the software.
 

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I've got a Rino 130 and love it. Has worked very well under many circumstances. Tree covered areas in central Texas. Canyons in Utah. You name it.

The current versions of Garmin Mapsource ( free download ) "speak" GPX but the native format is GDB ( previously MPS ). GPX is a cross-app XML-based format, that a lot of software fully "speak" - I have used it between MapSource and TopoFusion and some other trivial stuff w/o any issues.

I am a big fan of having the larger antenna, being that it's listening to a very faint signal I want the best reception I can reasonable get. That said, I do NOT carry my gps outside my camelbak ... too much likelihood of loss or damage ( I have in fact lost one to the trail because the mount broke when I wasn't looking, and grey/brown/dark-green units blend into ground cover way too well ).

Okay, that's my random thoughts. :D
 

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johnbspinnen' said:
The Garmin 305 will be out early January. It will be the shnizzet for cycling GPS so wait.
In a nutshell - better chip with self calibrating barometric pressure altimeter, heart rate and cadence available as add-ons
eh, I wouldn't consider a rechargeable battery with 12 hrs life to be the "shnizzet" but to each his/her own I guess
 

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Wow

roadiegonebad said:
eh, I wouldn't consider a rechargeable battery with 12 hrs life to be the "shnizzet" but to each his/her own I guess
Actually I hadn't noticed the battery thing - shame on me. :rolleyes: I was just excited about the altitude feature which solved the problems discussed above. I've been using the Magellen SportTrak Topo for close to a year and although the unit itself has proven trustworthy, reliable and easy to use, the problem with inaccuracy in altitude gain/lost (climbing) is a fundamental problem with the method used that was finally addressed by Garmin.

Although the rechargable battery thing initially seemed to be a drag, I'm trying to think of a time when I would've wanted more than a 12 hour life. Although I regularly ride for more than 12 hours I can't think of a time when I needed to GPS the whole route as it's usually in a 12/18 or 24 hour solo race which is just lap after lap anyway. I've mapped many trails and races courses, some are here here and here,. Now if I was riding across Arizona or doing the Great Divide Race, the battery thing would be a real problem, and the 305 certainly wouldn't be the choice.

I probably won't be doing either of those in the next year or two so I'm still considering the 305 highly. It'd be nice if the battery was easily replacable but I can't find info on that but will check.

eh, What kind of GPS unit do you use RoadieGoneBad? :confused:

W/regard to the barometric pressure calibrations above:

My Polar 725 uses a barometric pressure altimeter and you can see how changes in hourly barometric pressure effect the data by looking at the graph below of a hill repeat workout :



Although I live at sea level, I don't routinely calibrate the thing every ride, so the top (brown) line shows elevations below sea level and the elevation slowly rises throughout the workout as the barometric pressure changes. Even without calibration the error introduced is still far less than a GPS'd based calculation.
 
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