Edge 500 help please
 

Thanks. In advance for any help.
I was riding last night when the mph on my edge 500 began to fluctuate rapidly. The speed eventually just settled in around 6 mph and then it began to auto pause when still moving. The ride also registered 8 miles shorter than it actually was. Fire away with the slow jokes but if you mix any suggestions in it would be appreciated.

Do you have a speed / cadence sensor?

Assuming you don't was it an exceptionally cloudy night or were you riding in an area where it may have trouble receiving signal?

I do have a sensor. It i a route I ride frequently and it was a clear night. Never had problems before. Is there a battery in the unit on the chain stay? Thx

Yes, the speed/cadence sensor does have a battery. Sounds like it is time to replace it.

Thx for the help

I've had this happen and found it to be an incorrectly positioned cadence sensor. Battery could also be the issue.

Changed the battery. Just got back from a ride and the same thing is happening. I did just recently change wheel sets but I don't see how this should make a difference. Speed I all over the place and by the end of the ride it basically just goes to almost zero and auto pauses. The distance on the way out is correct while iy comes up two miles short on the way back. Carl,I will take a look at that. It seems the bike cadence is the only thing working. Any other suggestions are appreciated. Only had this thing for about 3000 miles.

You did move the magnet to the new wheel, right?

Ya. Should the silver screw, or the black back be facing the sensor?It is positioned slightly different than on the other wheel because the spokes are now flat. Thx

Are you sure the speed sensor is stilled paired with the 500?

How can I tell? Thx and sorry for all the dumb questions

I have the same issue when I ski (so no sensor issue) and the GPs is sometimes screwed as well. It also happens on the trainer and I have a powertap wheel (new battery) that sends speed signal to Garmin. I deleted my history, not that it was big, and it seems to slightly help... I still do get the random auto-pause.

Download the user's manual from Garmin's website, and RTFM. It'd be much quicker than waiting for us to come up with the answer. While you're on Garmin's site, look for the FAQ. I'm pretty sure you're not the first person this has happened to.

I don't think this is an issue with the speed/cadence sensor. When the 500 loses contact with the sensor, it defaults to the GPS for speed determination. If it were mine, I'd download all the data I want to keep, clear the history, leave it charging overnight, and try it again in the morning. This would be after checking the manual and the FAQ.

Will give that a shot. Thx

You need to use the test button and make sure that they sensors for the speed and cadence are correctly lined up. As said, the user's manual will tell you how to do this.

You're describing the EXACT same symptoms that I experienced after replacing pedals and nudging the sensor just a hair. Realigned the sensor and it worked perfectly!

Reset did not work either. While sitting in my chair the device had me moving between 1 and 6 mph. Magnets are lined up correctly and gsc 10 reset. Trying to contact garmin

One other thing I just noticed. When resetting the gsc10 it is registering the Cadence magnet on the peddle with a red led flash, however it is not flashing green when the spoke magnet passes. It is lined up with the mark and I have even moved the gsc10 arm closer. Thanks again for the feedback fellas. I sure hope I can return the unit if it is not fixable. I am having trouble locating my receipt.

The green light has to also be flashing for the unit to be properly set up (I forget which light is for which sensor (speed/cadence))

I read somewhere when replacing the battery that you need to keep it out for at least a minute. I can't recall where I read it or how accurate it is but it's worth trying.

I had problems very similar to what you're describing when mine was NEW! Shorter than actual rides, erratic speeds...

For a while, I just turned off the speed sensing portion and went with GPS, but that fluctuates with GPS error, so that may bug you (it bugs me). I replaced the battery, that didn't work. I put rare earth magnets on the spoke and crank magnets to get "closer" to the sensor, and it worked for the crank but not the wheel. (the magnet should face the wheel, not the screw. make sure you're using the correct spoke channel, there's one for bladed spokes and one for round).

I ended up replacing the unit and the new one worked perfectly from day one. Go figure. Wahoo also makes speed and cadence sensors that will work with ANT+ garmins if you want to ditch your garmin supplied unit.

Just a thought, but have you manually entered your wheel size into your bike profile. I've found that Garmin units never give correct speed/distance readings if you let them auto calculate, but instead do much better when you manually enter the wheel size into your bike profile. The owners manual has a table that gives you the correct metric readings for all common wheel sizes.

Yes, and garmin customer care alsos mailed me saying that they suggest that the battery be inserted upside down after removing it, then leave it out for a few minutes and then put in a new battery. Something to do with discharging some thingamajig inside the unit.

That is normal. If your wheel speed sensor is not transmitting then the unit will use GPS for speed data. While sitting inside you have a very poor lock, so at times the unit may think it's moving.

That is the problem right there.

I would keep fiddling with the arm and the magnet. The reset button only makes things blink for 60 seconds. I would keep hitting it while you adjust the arm and the sensor. Go so far as to have the sensor actually lightly touch the arm each time by. If it's still not working then try the suggestion below:

It's called a capacitor. :)

Thanks again for all the help fellas. The green light on the gsc 10 is now working when the spoke magnet passes. May have always been working but it was too light outside. I will be trying these other suggestions today. One other thing I did Not mention is the unit actually totally lost its charge after not being used for a while. This is the first time it's battery was completely drained. It is since the recharge that this has been happening. That is the only other variable besides the wheel change that sits between it workin perfectly and now barely working. Would this have an effect? It did still have past ride data on it. I will say a gain that I really appreciate all of you that have taken the time to try and help.

Tried everything suggested so far. Speed Is still all over the place when riding at same pace. It seems that something went wrong with the unit. Just seems odd that it happens after not using it for two months for no apparent reason.

Try removing the speed / cadence sensor and ride just using GPS (change setting on computer to remove the sensor), see if it is accurate that way. By doing this you will be able to at least eliminate the 500 as the problem. If everything works fine it may be time to contact Garmin about warrantying the sensor. Just so you know, they are great about handling problems.

Electronics, especially those with batteries, are more likely to fail after they've been sitting completely idle for a month or more. I'd say you've exhausted almost all of the troubleshooting steps you have short of running it just on GPS...probably time to stop frustrating yourself trying to fix it and get in touch with Garmin.

Agree with others here that it may be time to give the fine folks at Garmin a call as they are usually very helpful and cooperative. However, there is one more thing you can look at as I had similar issues with my 500 that ultimately turned out to be a rusted cadence sensor on the crankarm. The magnet inside the plastic housing was literally rusting apart... crumbling. Replaced it with a new one and made sure the alignments on both magnets were perfect and that seemsed to do the trick. Note that I also replaced the battery on the unit as well as several of the other suggested fixes here as well. Was discussing the issue with one of the riders in our group who had an issue with his 500 as well... he replaced the crank arm magnet with one of the "rare earth" button magnets that drop into the hole at the end of the crank arm where you tighten the pedal. Realigned the GSC-10 on the chain stay so it lined up with the new magnet; realignd the spoke magnet and arm and hasn't had a problem since. I decided to drop the $5 on eBay and try the same thing... Now all three of my bikes use those magnets instead of the stock Garmin magnet that zip ties to the crank arm. Works like a charm and no ugly zip tied magnet on my crank arm...

The reed sensor in speed arm of the Garmin GSC-10 is prone to failure either due to shock or water ingress. I have had two units fail in the exact same way in the past year. Failure will be intermittent at first but then absolute: auto-pause will come on randomly then eventually the green led will not light at all when the speed magnet passes. Get Garmin to replace it under warranty, or buy a new non-Garmin sensor. I like the Motorola or Bontrager Interchange ones. They appear to be a more sturdy design and can be easily swapped between bikes because they don't need cable ties to attach. The Wahoo/Timex type sensor is another alternative which is particularly good for curved chainstays because the speed and cadence sensors can be positioned independently.

Thanks. I will take the sensor off today for my ride. My situation sure does sound similar to yours,bones. I will look at other sensors.