How critical is it to adjust GPS "straight lines" on TransAmerica maps?

[kenrinehart]

Hello,

I am new to this forum. Thank you for taking my question.

 I purchased the TransAmerica Bike Trail maps and I'm making plans to ride across the mid-section this summer with three friends.

I hope to learn from this forum, How important is it to correct the "straight lines" that are created by GPS TransAmerica Bike Trail GPS coordinates?

I am using the Garmin RoadTrip 2009 maps (for Mac) and the Garmin 705 on my bike.

Do the provided GPS coordinates provide sufficient data to take me from point-to-point (displayed as a straight line) or do I need to add hundreds of additional waypoints in make it follow the road? 

There are lots of places where the provided GPS calculated bike route deviates from the written map instructions.  I don't see any control mechanisms to enhance the calculated route adherence to the main designated route. 

Also, I can't figure out how to eliminate some map routes that are incorrectly displayed, but don't provide a waypoint to pull into position. 

Can someone help me, please?

Thank you.

[FredHiltz]

Hi Ken,

The Edge 705 is an excellent choice for local training rides, perhaps the fanciest cycle computer on the planet, but is not well suited to navigating long trips for two main reasons. Its built-in battery needs recharging every night and its navigation abilities are limited.

For other people thinking about a GPSR for long rides, check out the Garmin Etrex and GPSMAP series and similar units from Magellan. They can manage at least half the TransAmerica route in a single memory load.

Ken, you could still use the maps in the 705 and navigate to one location at a time. As you have found, the GPSR often chooses its own idea of the best route to a chosen location. On other units, you can give it a few intermediate waypoints, sometimes called vias, to guide its choice along the roads you want. However, from all I can see in the owner's manual and a few reviews, one cannot create multi-point routes on the 705 itself. (It can be done on a computer and loaded into the 705.) You would need to mark a location part way along the road you want, mark another when you get there, etc. Probably not worth the effort. You can still see where you are on the map, though, and that is valuable.

Can any other 705 users confirm this and supply some more details?

Fred

[staehpj1]

Just one person's opinion, but...

With the TA maps I didn't find a GPS worth carrying.  I sent it home after a week.  The AC maps were easy enough to use that we felt no need to supplement them with anything but a state map picked up each time we entered a new state.  We did intentionally go off route once in a while using an alternate route that the AC maps did not cover and that was the only time the GPS would have been used.

On the 705, I don't think it is really a good design for touring.  Keeping it charged will be a hassle and the features aren't really there for touring.

[kenrinehart]

Thank you both for the input.  This is turning into quite an expensive and time-consuming learning curve operating a GPS unit.
Ken

[centrider]

I have a Garmin 705.  By and large I agree with with  previous postings.  I've found it useful to tell me where I've been.  It is too difficult (for me) to really navigate using it.  Occasionally I've used it to get me back to the beginning of a ride.  Unfortunately, if the route back is not along the route out the 705 will try to get you back to the outbound route instead of taking what I would consider to be the shortest.  Unless you can find a way to easily load the route you want into your GPS, I think doing it by hand is tedious.

I've found it useful if I'm looking for an intersection, or if one is let's say a mile up the road, It can inform me of that.  Outside of towns, I have it set so the display = 1 mile.  As one country road disappears off the back of the unit, another one comes in at the top.

Battery life is a problem, but because I travel with my wife as SAG, and we overnight usually in motels that's not much of a problem.  Even so I've carried a backup charger (which of course has to be charged).

Finally even using my GPS in my car I find it's advisable to have a good map.  The ACA maps are excellent.  Many a trip was taken using only their maps.  I showed the Lewis & Clark map to a volunteer in a S.D. tourist center who swore that the SD Dept of Transport, or whom ever did their maps, made the best maps of S.D.  That is, until she looked at the ACA map.