RVD72

Hi everyone,

I tried to search but didn't find anything so here goes.

I was on a 45 mile ride on Saturday but the weather was pretty cloudy. It didn't rain or anything but the sky was definitely overcast.

My garmin 705 basically wasn't working. It had trouble connecting to satellites, it would auto pause frequently when I was riding, the speedometer was way off saying that I'm going 6 MPH or 40 MPH when I was probably between 18-20 MPH, etc.

Needless to say, in the end my data was all screwed up. It said that I did the 45 mile ride in 2 hours, etc. when it really took me more like 3 hours. I'm guessing that the cadence and heart rate monitor were fine.

Is this normal behavior? Is there any way to make this function better? Perhaps better placement on the handle, etc.?

RVD.

Sooner Rider

That's not normal, but you need to provide a little more information. How long have you had it, have you changed the placement location, how old are the batteries, are you using the latest firmware, etc? My 305 worked just fine in Colorado over the weekend, but that's because I was closer to the satellites.

brian416

how old is your cadence sensor battery, the auto-pausing often is a sing of a dying cadence battery

RVD72

The unit is pretty new (maybe a month or so old). I just attached the cadence sensor a couple of weeks ago and used the heart rate monitor for the first time on this ride. The placement location is the same as it has always been and the unit was fully charged.

I downloaded the ride to my computer and the cadence and HRM seem like it worked fine. It's just the MPH that's way off and I guess the time of riding.

I don't know if I'm using the latest firmware. I haven't updated it though since buying it so it may not.

RVD.

Sooner Rider

"How long have you had it?" My mistake. What's more important is how many times you've ridden with it, but either way, it sounds like an almost out-of-the-box-new GPS. I've had a few 305's including replacements, and know lots of guys who ride with them, and they're notorious for being quirky for the first several uses. Don't know why, but they seem to be. So...
1) Sync and download/install the latest Garmin unit firmware; 2) Give it 5 minutes before each ride to acquire good satellite coverage; 3) When storing bike between rides, make sure that pedal crank arm with sensor is not next to the receiver on the chain stay; 4) Take it with you in your car while you commute or run a few errands, so you can test it there (but don't post here later with a screenshot showing a 70 mph high speed on a "recent ride").

Hunt-man

Try updating it. Go to Garmin and download the updater tool. Not to hard. If that isn't it sounds like you should talk to tech support or return it for a new one. Not right. My GPS works indoors sometimes.

rdtompki

I believe autopause is based solely on GPS, but I might be mistaken.

I've had a similar speed reading issue caused by my speed sensor arm not being close enough to the magnet. Speed would jump from below my actual speed to above my actual speed. Adjusted the position of the arm and all was well.

RVD72

ok thanks. will play around with it some more. guess this isn't normal behavior.

yes, it's pretty new and it's only been used around 5 times. it was fine on all of my rides until Saturday.

RVD.

RoboCheme

I got a lot of auto pauses and otherwise bad readings because my magnet wasn't close enough to the speed sensor.

Do you have the speed sensor turned on? ( you can have the Garmin use GPS and the speed sensor or either the GPS or the speed sensor)

RVD72

hmm, that's exactly the behavior that i was seeing. how do i change the GPS to turn on the speed sensor? how do i set it up to use GPS and speed sensor or just GPS or just speed sensor? i checked in the settings area but couldn't find it.

i have cadence turned on and it seems to work. perhaps it's not aligned properly?

RVD.

RoboCheme

I remembered incorrectly. You can only turn off the GPS. (Settings/System/GPS)

My guess is that you don't have the magnet close enough to the speed sensor. If it just senses the magnet intermittently, you'll get flaky speeds. If it doesn't sense the magnet at all, it'll use the GPS, which will cut out under heavy tree cover.

Or your sensor battery is weak. In that case, the cadence will work, but the speed won't (or so I've been told).

benajah

For what they cost, you should not have to fight with it. Take it in for a replacement. Garmin has a great customer service policy (shameless plug I used to work for them in the late 90s designing base maps when they were first coming along) If it is having trouble picking up satellites in cloudy weather, 10 years ago it could likely just be the weather but the antennas are way more sensitive these days and cloudy weather should not hurt performance. I can use mine on the mtb in heavy forest and get an okay signal.
Remember that to turn on the speed sensor you have to specify what your wheel size is, they are made for any kind of bike. I'm not sure how to do it though.
Most likely an issue with the unit. Like others have said download the latest firmware, and if you still have a problem take it in for a replacement.
For the amount of money those things cost, you should not have to wrestle with it, just take it in.

luker

the latest firmware says that it fixes "spurious autopauses"...it seems to have fixed mine.

RVD72

I updated the latest firmware so I'll give it another shot (hopefully tomorrow). I did check the cadence and speed sensor and they look aligned properly. I don't know about the battery power (I will probably try changing the battery next if this doesn't work).

If all else fails, I'll take it back for a replacement.

RVD.

SeaBee

To make sure - do the red/green light test to see whether it's properly aligned. You just press the button on the GSCS and give the wheel a spin - it the turns red/green as it picks up the wheel sensor passing/cadence sensor passing.

Simple enough test to see if everything's aligned.

Hunt-man

I bet it will work fine now. If it doesn't get a replacement. My battery will last almost a week, depending on how long my rides are. Don't charge it after every ride, it will last a long time.