Was my Edge 500 trying to tell me something

[walkerr]

Last Friday my Edge 500 started showing erratic speeds, and was giving dodgy looking speed and distance data throughout Saturday's Wellington ride.

 

From what I've read, that is often a problem with either the battery or the position of the speed/cadence sensor. Seems like the Edge only uses GPS data if the speed sensor is not present. If present, but mis-functioning it will still use the bad data.

 

The battery is fine, and nothing had changed from the many countless previous rides.

 

Within 200m of the timing matt's, BANG, my back wheel broke a spoke, and I carried the bike over the line. Not good as the Easton's are less than 6 months old with < 1000kms on them, but that is another story.

 

What I'm wondering now - was the Garmin dodgy signal actually an early warning sign that my rear wheel had slipped out of true slightly, making the magnet not pass the sensor quite right. I did a cursory check free spinning both wheels and looking against blocks/fork pre-ride as always. But that would only show a gross truing issue, not something subtle but dodgy.

 

Seems way too much of a coincidence to me that my wheel broke so soon after a ms-alignment problem with the sensor. I was also really struggling with my pace on the ride, not based on Garmin stats which were out but purely based on feel and mental time/distance calculations. That also makes me wonder if I was getting a very slight or occasional friction rub against the brake pads too, or just more effort needed to spin a ever so slightly out of true wheel.

 

I have my old training wheels on now, with magnet re-fitted and all is working fine - so nothing is wrong with the Garmin, sensor battery etc.

[Tiny K]

update firmware. I got a ride that measured 15000Km about - plotted a point in Antarctica.

 

Edit: but as you say, it could have been your wheel going out of true.... but not that much surely!

 

Edit 2: I use satellites for my distance and speed. Only use the magnet when I am on the IDT.

Edited February 28, 2012 by Tiny K

[walkerr]

update firmware. I got a ride that measured 15000Km about - plotted a point in Antarctica.

 

Edit: but as you say, it could have been your wheel going out of true.... but not that much surely!

 

Edit 2: I use satellites for my distance and speed. Only use the magnet when I am on the IDT.

 

Antartica - now that is impressive, how were the penguins?

 

Yeah - agree, it's a stretch to think the truing could be that far out. But no past issues with wheels or Garmin, and then both go at once, who doesn't love a good conspiracy.

 

I may switch mine to only use GPS I think from now on.

Edited February 28, 2012 by walkerr

[riaanb]

Last Friday my Edge 500 started showing erratic speeds, and was giving dodgy looking speed and distance data throughout Saturday's Wellington ride.

 

From what I've read, that is often a problem with either the battery or the position of the speed/cadence sensor. Seems like the Edge only uses GPS data if the speed sensor is not present. If present, but mis-functioning it will still use the bad data.

 

The battery is fine, and nothing had changed from the many countless previous rides.

 

Within 200m of the timing matt's, BANG, my back wheel broke a spoke, and I carried the bike over the line. Not good as the Easton's are less than 6 months old with < 1000kms on them, but that is another story.

 

What I'm wondering now - was the Garmin dodgy signal actually an early warning sign that my rear wheel had slipped out of true slightly, making the magnet not pass the sensor quite right. I did a cursory check free spinning both wheels and looking against blocks/fork pre-ride as always. But that would only show a gross truing issue, not something subtle but dodgy.

 

Seems way too much of a coincidence to me that my wheel broke so soon after a ms-alignment problem with the sensor. I was also really struggling with my pace on the ride, not based on Garmin stats which were out but purely based on feel and mental time/distance calculations. That also makes me wonder if I was getting a very slight or occasional friction rub against the brake pads too, or just more effort needed to spin a ever so slightly out of true wheel.

 

I have my old training wheels on now, with magnet re-fitted and all is working fine - so nothing is wrong with the Garmin, sensor battery etc.

 

I've had a similar problem twice, when changing wheels between traiingn and racing the little magnest on the spoke sometimes bumps against the speed/cadence sensor each revolution and then gives strange readings. Realign and everything is fine.

[walkerr]

I've had a similar problem twice, when changing wheels between traiingn and racing the little magnest on the spoke sometimes bumps against the speed/cadence sensor each revolution and then gives strange readings. Realign and everything is fine.

 

Thanks - done that and all is good, in fact I had too when the Easton's went off for repair.

 

Just seems odd the broken spoke was 1 spoke away from the magnet, and nothing had changed - made me wonder if I developed a slight wobble as the wheel went out of true, which also showed up with the magnet not also passing the sensor bang on.

[goya-goya]

dude...

 

I have the same issue on my stationary bike... It is a carbon frame and when I stand and the bike sways slightly... and the magnet moves because it hits the arm of the speed & cadence sensor... it goes south!!

 

speed mostly is halved... but it bounces between zero halved and proper speed...

 

Best fix is to fasten the sucker tight as hell on the spoke!

[walkerr]

Will do .... assuming I still have some spokes that aren't broken!

 

Still bummed about my busted wheel. Holding thumbs it's fixed for Argus time