Edge 605/705 Accuracy

NWLondoner

Today i gave my 605 a real test in the City Of London.

Sadly it failed. From my home to Blackfriars it was fine but as soon as i got to Mansion House it was not very accurate.Even going down Tooley St to Tower Bridge the route was about 6 mtrs off the actual road. I suffered to the same problems when i hit Aldgate and ended up getting lost on the damn one way system around Liverpool Street :roll:

How accurate have you managed to get it to work?

I

fto-si

Hand held / bike mounted GPS units will be accurate within 20 metres so 6 metres is nothing out of the ordinary, in fact its pretty good.

a_n_t

there's a setting in the 705 somewhere "follow road" i think which forces it to do just that.
18 ft is pretty good tho!

Kafka\'s Doll

NWLondoner wrote:

Today i gave my 605 a real test in the City Of London.

Sadly it failed. From my home to Blackfriars it was fine but as soon as i got to Mansion House it was not very accurate.Even going down Tooley St to Tower Bridge the route was about 6 mtrs off the actual road. I suffered to the same problems when i hit Aldgate and ended up getting lost on the damn one way system around Liverpool Street :roll:

How accurate have you managed to get it to work?

I

I work in Barbican and when setting off from there it takes quite a while (well, up to five minutes) to 'find' me. But thereafter it seems to be extremely accurate.

hazychris

NWLondoner wrote:

How accurate have you managed to get it to work?

Mine's been very good, even down to the correct side of the road - but then living out in the sticks means no tall buildings as well as no cars on the road ;-)

Cheers,
Chris

JWSurrey

I've got the earlier 305, and I think the last post hits the nail on the head... same as the car GPS actually...
In Central London, the sky-shot opportunity to pick up enough satellites to be accurate, is pretty poor at the best of times - which is why in-built car sat. navs usually are backed-up with gyroscopes.

Once you get away from the tall buildings, the accuracy improves greatly.

MegaCycle

what about the altitude? My house is at 25m one day and then 85m the next! How can it be so inaccurate and so variable?

Anyone have any idea?

And the calories burned figures are absurd!

You'd think for £250 they could do a bit better than that,

aracer

Because GPS altitude is a load of rubbish - that 60m variation is well within what you'd expect for GPS. OTOH the Edge 305 at least has a barometric altimeter which should get rid of that problem - the issue you then have is that a front coming through will make a big change. If you calibrate it properly though (or let it auto calibrate as my Etrex Summit certainly does) then it should at least be consistent unlike the GPS altitude.

In case anybody is interested in why - it's because the triangulation is nowhere near so good in the vertical as in the horizontal since satellites tend to be close to overhead.

kettrinboy

i find on my edge 305 the altitude is usually plus or minus 5 m of the true value after a 2 minute warm up but if its 30 to 40 metres off which happens sometimes if you leave it for an hour switched on it comes back close to the true value, theres odd days though when it remains 30 to 40 metres off ,just have to live with it i suppose

MegaCycle

aracer wrote:

Because GPS altitude is a load of rubbish - that 60m variation is well within what you'd expect for GPS. OTOH the Edge 305 at least has a barometric altimeter which should get rid of that problem - the issue you then have is that a front coming through will make a big change. If you calibrate it properly though (or let it auto calibrate as my Etrex Summit certainly does) then it should at least be consistent unlike the GPS altitude.

In case anybody is interested in why - it's because the triangulation is nowhere near so good in the vertical as in the horizontal since satellites tend to be close to overhead.

...but I have a 705... aren't they barometric, which is supposed to be dead accurate. Although quite how it can be when air pressure changes with the weather, God knows!

willbevan

hmmm i have a forerunner 305, so no barometric altimeter like the pure cycling bretheren the edge 305. When i compare the elevation profiles from the GPS to the map based elevation from memory map (i know there not spot on either) they are pretty close, and by the end of the ride the difference between my start height and finish height is okay, not spot on again, but maybe within 10ft. Okay eveyone's definition of 'okay; is different and i do live in the sticks so the largest problem to sky visibility is me!

a_n_t

aracer wrote:

Because GPS altitude is a load of rubbish .

good job the 705 is barometric then hey?


not noticed a problem with mine, always around 100 ft above.

aracer

I did point out the issues with both - GPS suffers from big short term variation, barometric suffers from potentially bigger long term variation, but should be stable once calibrated until a front comes through. Hence until calibrated a baro could produce exactly the variation he describes.

spivvy

Why we don't have a manual altimeter calibration setting on these devices is a mystery to me - the majority of the Garmin handhelds have it.
Still it's early days for the 705 :?

MegaCycle

Frankly, I'm about to chuck my 705 in the bin. it's rubbish! I bought it thinking it would be the dog's bollocks!

a_n_t

gotta say I love mine!

Kafka\'s Doll

MegaCycle wrote:

Frankly, I'm about to chuck my 705 in the bin. it's rubbish! I bought it thinking it would be the dog's bollocks!

I'm starting to wonder whether you're a Satmap plant. The 705 is an incredible bit of kit.

NWLondoner

I tried mine again today and it went a bit funny. The start of my route is the same as my route home and was getting confused. It told me ti turn right when i have to turn left and in the end it froze. I manged to reset it further down my route and it worked fine.

My only concern is that it is very late in giving warings. i.e turn left. I missed my turning off the Harrow Road/westway because borth the warning and purple route only showed the turning when i had 2 mtrs left to turn.So instead of going accross the railway bridges to Paddington i had to shoot down to Edgware Road.

What ZOOM lever do you use?

pjh

I've had my 705 for about a month and it's a fantastic bit of kit. Accuracy down to 10ft seems pretty normal most of the time

The motionbased analysis stuff is also great.

Can't fault it so far

MegaCycle

Kafka\'s Doll wrote:

MegaCycle wrote:

Frankly, I'm about to chuck my 705 in the bin. it's rubbish! I bought it thinking it would be the dog's bollocks!

I'm starting to wonder whether you're a Satmap plant. The 705 is an incredible bit of kit.

Well it's ok for recording where i've been, but that only makes it a sort of glorified cycle computer. I really cannot figure out how in Earth you could ever navigate anywhere with it. I just tried uploading a .gpx file from map my ride and when I try getting it to navigate it just truncates the route for some reason!

And how on Earth you're supposed to learn how to use it from the absolutely useless manual they provide, God knows!

Not happy!

JWSurrey

As a barometric altimeter, it's best to use it to work out change in altitude / total climb for your day's cycling, rather than for the absolute figures.
I think it is downloading to Motionbased.com of your track, that will then correct the altitude - I guess motionbased is using static height data. There's certainly at least one site out there which will do this.

As mentioned in previous posts, changes in barometric pressure can still occur throughout the day, though the variation in height is not usually much ( a few feet).

With regard to calorie burn, I did read a post that said Garmin use a non-copyrighted formula, which is less accurate than other devices.... Personally, I use a separate Polar F11 heart rate monitor for it's additional features and greater accuracy.

On the 305, the routes (and therefore the turn points) are uploaded from my computer.
When doing so, the alarm point/radius can be modified to different distances.
I also find it useful to put the turn a few metres before the actual turn, and to sometimes sign the next waypoint at 90 degrees to the current direction, just to make it really obvious.

Yes, it's a shame that when connected to TrainingCenter there isn't a link up to some sort of mapping software to auto correct the barometric altimeter.

Kafka\'s Doll

MegaCycle wrote:

Kafka\'s Doll wrote:

MegaCycle wrote:

Frankly, I'm about to chuck my 705 in the bin. it's rubbish! I bought it thinking it would be the dog's bollocks!

I'm starting to wonder whether you're a Satmap plant. The 705 is an incredible bit of kit.

I really cannot figure out how in Earth you could ever navigate anywhere with it.

Yeah, it's really complicated. You click Find places, Addresses, type in a postcode and follow the route. How I'm supposed to manage that without three phDs is anyone's guess.

MegaCycle

Kafka\'s Doll wrote:

MegaCycle wrote:

Kafka\'s Doll wrote:

MegaCycle wrote:

Frankly, I'm about to chuck my 705 in the bin. it's rubbish! I bought it thinking it would be the dog's bollocks!

I'm starting to wonder whether you're a Satmap plant. The 705 is an incredible bit of kit.

I really cannot figure out how in Earth you could ever navigate anywhere with it.

Yeah, it's really complicated. You click Find places, Addresses, type in a postcode and follow the route. How I'm supposed to manage that without three phDs is anyone's guess.

why would you want to cycle somewhere using a postcode? I'm talking about following a course like you find on mapmyride or somesuch. It's pretty unclear whether you're supposed to use a .gpx file, a .crs file and .tcx file or what? the damn manual doesn't tell you for sure! And when you do upload the damn files it tells you it's truncated the course and leads you from start to finish in a short loop!

Winston Smith

Try BikeRouteToaster, save the route as a GPX and load it into the GPX folder on the device. This seems to work okay unless you leave the route, then it recalculates it and sends you to the end the fastest possible way, even if the course is a loop and you're only 1 mile into a route of 50m miles. If you choose to leave the route briefly remember to press Stop so that it doesn't recalculate.

Kafka\'s Doll

MegaCycle wrote:

Kafka\'s Doll wrote:

MegaCycle wrote:

Kafka\'s Doll wrote:

MegaCycle wrote:

Frankly, I'm about to chuck my 705 in the bin. it's rubbish! I bought it thinking it would be the dog's bollocks!

I'm starting to wonder whether you're a Satmap plant. The 705 is an incredible bit of kit.

I really cannot figure out how in Earth you could ever navigate anywhere with it.

Yeah, it's really complicated. You click Find places, Addresses, type in a postcode and follow the route. How I'm supposed to manage that without three phDs is anyone's guess.

why would you want to cycle somewhere using a postcode? I'm talking about following a course like you find on mapmyride or somesuch. It's pretty unclear whether you're supposed to use a .gpx file, a .crs file and .tcx file or what? the damn manual doesn't tell you for sure! And when you do upload the damn files it tells you it's truncated the course and leads you from start to finish in a short loop!

Personally I just copy routes from Bikely and follow them. Again, I seem to manage this without advanced degrees in software engineering.

a_n_t

not had any mither using mapsource.

create route > send to device > job done!