Swap head units with somebody and see which end the problem is.
Make sure you are running up to date firmware.

I'd be trying a new battery in your Stages first. I haven't heard of any issues with them from my friends that use them.

Usually a Stages and Garmin Edge 500 are a good combo, at least, the signal being good. I'm guessing either the ANT+ signal coming out of the Stages is weak (possibly low battery), or the antenna receiver in the Edge 500 is weak. I'd probably first change the battery in the Stages and see if that fixes it. If not, try a different cycling computer, even a Forerunner, or borrow an Edge from a friend.

I did the coaching thing a couple years ago and he always recommended "anything but Stages" because he would have to go through the power files and delete all the drops. Newer versions seem to have fewer problem.

Check for software updates and put in a new battery and see if anything improves.

I put a new battery in. Seems to have helped. Was a trainer ride had trainerroad on my macbook, the stages app, and my garmin all displaying power (all slightly different) Only saw one drop on trainerroad for a second over the course of an hour.

I'm still not convinced but I'm in a taper right now a week out from a race. So, we shall see.

I'd love it if you would post back here and let us know how it goes over a longer period of time. I'm >this< close to getting a Stages but a bit concerned since I use a Garmin 520 on their out front mount and I've read lots of horror stories. Thanks.

Will do. My next outside ride is Wednesday. I'll report back after that.

New PM, especially if you have a water bottle near the Garmin.

I've had issues with stages. Their support has been great though. I've never has an issue though with my 500 edge and dropped signal. I have the edge at the end of my aero bars and I use a bta bottle.

I have the same combo, with the 500 generally on top of my BTA bottle.

If I have a BTA and no seat-tube bottle, I have no problem. Adding a seat-tube bottle causes the occasional drop. For the new season I'll be experimenting with an aero seat-tube bottle and a slightly different position for the 500 on the aerobars or perhaps on the stem. On the road bike I have zero problems, presumably due to the sensors being physically closer and having fewer obstructions.
I'm 90% happy with the combo, and I'm confident that with a few tweaks I can push that closer to 95%!!

---

-----
http://www.howesgreg.com

Maybe this is worth checking... Is your wifi router broadcasting in 2.4Ghz?

If so, this could be the reason... ANT+ devices also broadcasts on 2.4GHz, so a interferance is most likely to happen. Just try to change your wifi router channel and check if the problem persists.

I had the same issues. Stages said that it was most likely that because i had the Garmin on top of my BTA bottle, the signal wasn't strong enough to transmit through water.

I bought a Wahoo Bolt (connects to the PM via Bluetooth rather than ANT+). It works like a dream. Great all around head unit, too.

A few people have eluded to water bottle but I just have the two normal bottles like a road bike. No handle bar bottle.

I know this is picky and grumpy but I don't want to have to fiddle with it. For the money I want something that just works. I don't want to have to deal with it. I'll see if the new battery made a difference if not then i'll change directions.

The Stages is the culprit, not the Edge. It seems all I ever hear about that thing is power drops with this device, with that device. etc. If Stages has a defining trait, that's it.

Looks like I'll be shopping. Had a few drops on this ride.

At this point I don't believe it. I'll be going crank based.

New battery
Updated firmware on Stages
Updated firmware on Garmin

Worked fine with Bluetooth and MacBook And stages app.

I think its an ant+ Issue.

Bummer. Thanks for the update. I might eye the new pedal solutions, but the $350 closeout was tempting.

I haven't seen this mentioned yet, so thought I'd add it. My Vector and 510 used to get frequent dropouts(short zero readings). I did two things at the same time, and as it fixed my problems haven't played further to find which one helped. First is to wake up all of your sensors first, BEFORE you turn on the head unit. (The second won't apply to the 500, but leaving here for reference, is to leave bluetooth turned off on the head unit, and just turn it on after a ride to sync the data)