gps do they work

[andym]

My sixpennyworth.

Do they work? Well yes as a way to conveniently carry detailed mapping, and to tell you where you are, to record where you've been (if that's what interests you) and to follow a route you have programmed. Don't get something like a Garmin if you want something to tell you where to go.

I have Garmin cityNavigator but while it's good value for what you get (get the DVD not the SD card version), I'm increasingly thinking that OpencycleMap is a better alternative as you can get topographic mapping. Personally I've never had success with City Navigator's turn-by-turn routing. Don't buy it on the strength of that.

Other things to consider when you're buying a GPS:

- the monochrome models represent poor value for money incomparison to the newer colour screen models - I'd only buy one if i could get one very cheap;

- the eTrex models use AA batteries - which for me is a huge advantage;

- the screen on the eTrexes is pretty small, and the newer generation have larger screens however, the price you pay for this is that they are dimmer and battery life is less;

- be aware that the eTrexes come in different models, HC or HCx. The x indicates that there's a memory card slot. Without a memory card you are very limited in the amount of mapping you can carry - so I'd go for an HCx;

- the models like the 705 are marketed as bike-specific. But unless you want to use them for training they don't really offer any particular advantages for a touring cyclist. they are expensive relative to the eTrexes (don't know about the 800);

- the Vista comes with a barometric altimeter. However the Legend also gives you an altitude reading using the GPS which I have always found perfectly fine. The vista will give you a nice altitude profile, but don't think you have to buy one in order to get a way to have an altitude reading;

- the new models (eg Dakota) have some advantages over the older models - eg greater internal memory, the ability to hold more tracks and custom maps. Worth considering if you can get a decent price.

 

[andrew_s]

I've found that turn by turn routing does work, provided that you make allowances for its limitations. Routing and POI data is exactly the same as on a car satnav, and can be used on a bike gps in the same way, subject to the smaller screen and getting turn instructions by beep and screen text rather than voice.


It's set up for cars, and telling it you are on a bike will just make it avoid major roads without much regard for added distance. Bike routing won't give you any bike-only sections of route, or even routes where bikes are exempted from restrictions (eg one way systems in Belgian town centres get respected even though most one way streets are two way for bikes). I've found turn by turn routing for bikes only really works well within larger towns and cities where there are plenty of roads to choose from, and if you don't mind taking a route that's a bit longer in return for less traffic.

Points of interest (POIs - hotels, restaurants, cashpoints etc) are a selection rather than a comprehensive list. Data is mostly supplied by external companies, so for example you tend to get complete data for Travellodge or McDonalds, but privately run hotels and small cafes are often missing. In a car it doesn't matter so much that the hotel you get navigated to isn't necessarily the closest.

I tend to set up a route by giving it half a dozen or so intermediate points chosen so the shortest car distance between them goes the way I want to go, then just follow the turn by turn routing. I choose the points from a large scale map (1:250,000 to 1:400,000), and rely on automatic turn by turn routing within towns and cities where the large maps aren't detailed enough (switching to bike mode for the in town section).


OpenStreetMap mapping data (free) is now better than City Navigator in many areas. In other areas there are still missing roads, but on the whole the UK has a pretty complete road network. It can be used for automatic turn by turn routing (depending how your version has been set up), but things to watch for are that saying you are on a bike may allow the route to use any legal track or bridleway regardless of surface, and that larger roundabouts tend to get handled as a set of individual junctions rather than getting (eg) "3rd exit" like City Navigator gives.
I use Andy Gates' version - see his sig line on YACF posts.
The only extra cost over a suitable GPS (eg eTrex Legend HCx, £120) is a card to put the data on. 1GB is oodles of space.


When it comes to choosing a GPS, considerations are...
Built in rechargeable batteries basically last for 1 day's riding before needing to be charged for a few hours. AAs last for 3 or 4 days riding, and can just be swapped.
Map/no map - without a map, you can follow a pre-prepared route, record where you've been, and find your current grid ref. That's all.
Cards - if your GPS does maps, you want one that takes a card. Older mapping GPS that don't take cards will give problems with CN or OSM due to map tile sizes getting close to available storage (Garmin Metroguide came in smaller tiles).
Touchscreens make the display a bit dimmer, the on-screen buttons partly obscure the map, and unlike Real Buttons™, you can't control a touchscreen whilst looking at the road rather than the screen.
Raster mapping like the OS maps can only be used on newer Garmin GPS (Dakota, Oregon etc, not edge 800). It doesn't display over such a wide range of scales, costs quite a lot more, and doesn't give routing (you'd need OSM or CN as well). On the other hand, OS maps are familiar and have a fair bit of background information.
Compass sensor - without a compass sensor, any GPS will tell you the direction you are moving in, but if you aren't moving will show a random direction. GPS with a compass sensor generally switch from showing magnetic direction to movement direction at 3-4 mph.
Barometer sensor - useful if you have an interest in the amount of climbing you've done. GPS height fluctuates enough that total climbing for a ride can be inflated by a considerable amount - up to 25%. Also could be of interest for tracking weather changes if you are away from forecasts.
You'll need a specific cycling GPS for things like heart rate or cadence, or training functions like racing your previous performance on a circuit. Phones have limitations on battery life (can be as little as 2 hours), weatherproofing, and screen readability (the backlight doesn't exist that can compete with the sun - dedicated GPS have a reflective layer behind the LCD)

 

[pshore]

I use the OpenStreetMap based VeloMap (and OpenMtbMap) on my Garmin handheld and find the autorouting for bicycles very good. They are set to completely avoid main roads and you can choose if you want to use unpaved cycle routes etc.

If you already have a car Garmin satnav you can put it on that and try before you buy and new cycle satnav.

Personally, I would always plan a route myself on a paper map or online and save the GPX route to the satnav and follow it. No satnav algorithm can beat your own planning abilities. The auto routing is handy if you need to deviate from your planned route.

 

[pidgin08]

I use a Garmin Dakota 20 coupled with OpenSteetMap mapping downloaded from here. Works a bit more like a "sat nav" than the Vista alternatives and is cheaper than the Oregon models already suggested (in fact it's basically a little brother to the Oregon series) and the routing seems to be pretty good. Used it for a 3 week tour in the summer - inputed the next day's route the night before using an OS map to plan the route and spot any interesting lokking places to visit and then followed the GPS's directions - simples

regards,
Alex

 

[andym]

Turn-by-turn routing: experiment with it on short trips before you commit to using it on a long trip. If you can make it work then it's great but I never have (the low point was when the GPS told me to go to the routepoint I had programmed, then do a 180 degree turn and head up the A-road I wanted to avoid). It may well be that newer models are better - on the computer at home the routing seems to work fine. But in any event, I prefer simply to use waypoints as this gives me greater flexibility to improvise and/or amend the route - I've never ever been able or wanted, to stick entirely to a pre-planned route. GPS software makes it easy to succumb to the temptation of overplanning.

In thousands of miles of riding with a GPS without a barometric sensor i have never, ever, experienced anything of the order of a 25 per cent discrepancy. On a long climb along a route with a lot of trees or along a cliff edge it takes the GPS a little time to catch up, but never by any significant margin - at most 20 metres or so. Normally the altitude reading is within 3 metres of what the map says it should be.

 

[jags]

thanks a million lads for all the help, and sorry for been a complete fred on all things gps.
so basically if i buy the vista hcx sat nav will it come with a sd card and then do i just download open street map onto it is it that simple.
these things can get very complicated for a fool like me .
so please keep it simple .

 

[andym]

thanks a million lads for all the help, and sorry for been a complete fred on all things gps.
so basically if i buy the vista hcx sat nav will it come with a sd card and then do i just download open street map onto it is it that simple.
these things can get very complicated for a fool like me .
so please keep it simple .

SFAIK you need to buy the SD card (EDIT: I should have MicroSD or MicroSDHC card). Also you will need to find the OCM maps in Garmin compatible format (ie a .img file). these are available but you might have to do some legwork with Google. Before someone corrects me, I should say that there are more complicated ways of doing this but I'm assuming you, like me, draw the line at having to find and fiddle with your registry files.

 

[Ergle]

thanks a million lads for all the help, and sorry for been a complete fred on all things gps.
so basically if i buy the vista hcx sat nav will it come with a sd card and then do i just download open street map onto it is it that simple.
these things can get very complicated for a fool like me .
so please keep it simple .

I have a Legend HCx, but if I was shopping for one now i'd go for the Vista. I have downloaded the open street maps and open cycle maps and find them useful. I draw my route on Bikehike, save as a gpx file then upload into the Garmin. It took me a few hours to learn how to do all this using the excellent guides provided by people on these forums who know about these things, and because I am in my 50's, need to relearn if I leave it too long between rides. I also need specs to read the small screen so use a pair perched on the end of my nose!!

The thing I like is that I can plan my route (part of the fun) then follow it without having to stop to look at maps, which spoils my rhythm. If I deviate, then I can see on the map where i am, where I should be, and roads in between so its easy to correct. I cycle camp, so have Archies Campings on the SD card as well. All in all this thing is fantastic and a treasured part of my toy collection.

David

 

[jags]

anyone got an idea where is the best to buy the garmin, i tried emailing handtec .co.uk but got no reply ,just curious handtec have them for £125 but there much dearer anywhere else.
so got any links to a good site thanks
jags.

 

[zizou]

handtec tend to be the cheapest - although i havent ordered from them before so dont know what their service is like (i got evans to price match the handtec price)

 

[jags]

handtec tend to be the cheapest - although i havent ordered from them before so dont know what their service is like (i got evans to price match the handtec price)

thanks zizou and did evens match there price.

 

[andrew_s]

In thousands of miles of riding with a GPS without a barometric sensor i have never, ever, experienced anything of the order of a 25 per cent discrepancy. On a long climb along a route with a lot of trees or along a cliff edge it takes the GPS a little time to catch up, but never by any significant margin - at most 20 metres or so. Normally the altitude reading is within 3 metres of what the map says it should be.

The large errors aren't in the current height readings, but in the accumulated total climbing. The height error is about 3 times worse than the horizontal position error, and varies around the true height randomly. These random fluctuations end up getting added into the total climbing. There's some averaging, but you can't do too much or else the displayed heights become wrong enough to possibly cause problems. Going by the displayed heights when I start a ride, the averaging period is 3 or 4 minutes.

The worst I've seen was trying to calibrate my barometric cycle computer off someone else's non-barometric GPS - the height was continually drifting up and down by 40m or so. It would have put 2 or 300m of climbing on the total in about 15 minutes, sitting at a café table.

 

[zizou]

thanks zizou and did evens match there price.

yeah, saved about £50

Just take a print out of the product page (with the url address showing) and they will go and check it. Obviously has to be the same model and if the shop they are price matching with charge postage ontop then they will add that too.

 

[andym]

The large errors aren't in the current height readings, but in the accumulated total climbing. The height error is about 3 times worse than the horizontal position error, and varies around the true height randomly. These random fluctuations end up getting added into the total climbing. There's some averaging, but you can't do too much or else the displayed heights become wrong enough to possibly cause problems. Going by the displayed heights when I start a ride, the averaging period is 3 or 4 minutes.

The worst I've seen was trying to calibrate my barometric cycle computer off someone else's non-barometric GPS - the height was continually drifting up and down by 40m or so. It would have put 2 or 300m of climbing on the total in about 15 minutes, sitting at a café table.

I've never experienced anything like that. The GPS generally gives an altitude that's close to that of the map position. But I have heard horror stories about cheaper older generation GPSes eg the Garmin Gecko. Clearly it's going to vary with satellite reception: if you have a fix from half a dozen satellites then that's obviously going to be better than a couple. Also after a long climb through dense trees it can take time to catch up, but once it has it's stable and accurate.

I've also experienced days when a barometric altimeter fluctuated widely (although in fairness it wasn't a Garmin Vista)

Bottom line:

- if, like me, you only really want to know 'how much further to the top of this mountain?' then the GPS positioning does the job just fine unless you happen to be on a road carved out of a high sheer rock face that's cutting off your view of most of the available satellites;

- if you want accurate statistics on total amount of climbing you've done, for training or whatever then the most accurate figure is going to come from loading the track into your mapping software and getting it to compute the amount of climbing by comparing your position with the mapped altitude for that position;

- the Garmin Vista gives a nice display of the altitude profile for the riding you've done (and I'm guessing from your post, the total climbing). I can see that it might be interesting to have a look at at the end of a long day - but I suspect the novelty would wear off pretty quickly (but maybe that's just me).

As far as places to buy are concerned, Amazon is always worth checking.

 

[jags]

lads sorry about this but before i spend my hard earned cash,has anyone seen or used the satmap active 10, this looks the business .i know it's a lot more expensive but this would be the only gps i will buy ,might as well go the whole hog.