Garmin 500 double cadence reading

bigharj

My LBS set up my Garmin Edge 500 with a GSC10 sensor.

Over the last few rides and an earlier post about excessive cadence, it looks like the Garmin is simply doubling up the cadence reading.

Has anybody experiences this and what was the fix?

The unit pairs up prefectly though.

Harj

ben16v

you havent got 2 magnets on the rear wheel have you- possibly an old one from a previous computer and the new garmin one - ive seen it done before

bigharj

Nope, it's a brand new first time bike!

I have read lots of posts on the net but none with this specific problem, still searching though.

gloomyandy

If you pedal backwards do you still get a double reading? If so that would eliminate any problem from the back wheel moving. If you don't get a double reading, then perhaps the cadence sensor is picking up the wheel magnet moving, and so that may need to be adjusted on the wheel.

amaferanga

What's your average cadence from a ride then? Well over 100? Or are you getting occasional erroneous readings which could be due to interference?

rolf_f

gloomyandy wrote:

If you pedal backwards do you still get a double reading? If so that would eliminate any problem from the back wheel moving. If you don't get a double reading, then perhaps the cadence sensor is picking up the wheel magnet moving, and so that may need to be adjusted on the wheel.

He hasn't actually said that he has a wheel magnet - but if he does, he should remove it to see if that changes anything.

That said, if the wheel magnet was being picked up I'd have thought the recorded cadence would be rather more than doubled and very variable unless the bike was SS (and there's knack all point having a cadence sensor on a SS!).

bigharj

I have 2 magnets one on the wheel and one on the pedal. My cadence is showing at 115 - 125.

redvee

bigharj wrote:

I have 2 magnets one on the wheel and one on the pedal. My cadence is showing at 115 - 125.

Those figures are the same range as my maximum cadence, I've had spikes in excess of 200+.

Gizmodo

Where are you looking at the figures? Are you talking about the current cadence displayed on the device or the max/average readings once uploaded to a web site like Garmin Connect?

Upload your activity to a web site like Garmin Connect and you can examine the data across the whole ride. A maximum of about 120 is normal, as is an average of 90 ish.

The sensor simply counts the number of times the magnet (tied to your crank arm) passes. If you pedal forward then backward then the magnet may pass the sensor more times than expected. Sometimes this can give spikes in the readings of 200+

rolf_f

bigharj wrote:

I have 2 magnets one on the wheel and one on the pedal. My cadence is showing at 115 - 125.

If that is twice your actual cadence, you need to learn to pedal harder as you are tormenting your knees!

Anyway, whip the wheel magnet off and see if that changes anything.

bigharj

Messed about with the position of the sensor and it sddenly started to give a realsitic reading. Just been on a 10 miler and my average cadence read as 73rpm!

Talk about sensitive gadgets.

kevin69

i had double readings from my garmin sensor.
i moved the arm on the cadence sensor up above the body (rather than next to and below)
and the values went back to normal.
hth

dw300

Often wondered if when you aren't pedalling and have the cranks parallel to the ground with the left foot back, does it read multiple passes as its hovering next to the sensor?

I get readings up to about 220 too, usually early in the ride. i would think if its picking up the speed magnet that it'd register several hundred rpm cadence, and for the whole of the ride ..

Gizmodo

dw300 wrote:

Often wondered if when you aren't pedalling and have the cranks parallel to the ground with the left foot back, does it read multiple passes as its hovering next to the sensor?

Yes.

limbtree@mac.com

Had the same issue. I had tried the short cut of leaving my old Polar magnet on the crank arm. It is a much bigger magnet than the sleek Garmin unit. Must have been overwhelming the sensor. Installed the Garmin mag, problem solved.