Any major issues with Garmin's new magnet less speed/cadence sensors?

It could be that some part of the chain has a magnetized.

Has the bike ever been put in a shipping box? We had a bike where the chain got magnetized when the bike was shipped as the chain came too close to the SRM cadence magnet when it was slack. The magnetized section of the chain then caused speed jumps like the ones you are seeing.

One way to test the chain without having access to a Gaussmeter would be to place the sensor on the rear hub and then rotate the crank arm backwards. If you get a speed reading with the wheel stationary while the chain is rotating then some part of the chain is magnetized.

My chain has has definitely touched the SRM magnet; almost every time I remove the crank. This must be it, sorry Garmin.

auto pause/auto resume

Hard to believe that Garmin didn't know there was an issue with the speed sensor being placed on the rear hub when field testing was conducted before release. If the signal strength is marginal and the distance from the sensor to the receiver is critical, then it shouldn't be advertised as being suitable for either the front or rear hub. Guess I need to determine if my chain has become magnetized before I complain too much. Other than that, I like the speed and cadence sensors.

The times I have seen erratic speed problems it has been due to some magnetized of the drive chain. After waking the speed sensor up try turning the cranks backwards so that the hub mounted sensor remains stationary. Does the Edge register an speed? If so then some part of the chain has gotten magnetized and that is what is causing the problem. Another test is to put the sensor on the hub of the front wheel and see if that fixes the problem.

The times I have seen erratic speed problems it has been due to some magnetized of the drive chain. After waking the speed sensor up try turning the cranks backwards so that the hub mounted sensor remains stationary. Does the Edge register an speed? If so then some part of the chain has gotten magnetized and that is what is causing the problem. Another test is to put the sensor on the hub of the front wheel and see if that fixes the problem.

In my case it was either the cassette or hub. If I held the sensor at the bottom length of chain while I spun the cranks backwards there was no speed issue, but when I moved it closer to the cassette then it would start registering speeds while the bike was sitting still. Now it lives on the front hub and everything is hunky dory.

I went thru everything to get my new magnet less speed sensor working. Changed 3 batteries, and now found this post which talked about the fact that the new sensor works based on the earths magnetic field.

Re tested with the bike mounted on a trainer, and the rear wheel free to spin like in coasting, and everything is fine when the left crank arm is facing forwards, while the speed shows zero when the left crank arm is backwards and towards the rear hub. Realised that I had used a rare earth magnet on my crank for a year with my old sensor, so I guess that crank arm is magnetised.

Any solution?

I had posted this before reading this thread.

Now, I wonder if it is the crank arm at all. It is alloy right? Ultegra. So, it should NOT get magnetised?

I did the test of holding the wheel still and rotating the crank backwards, and the speed shows pretty high, so I'm guessing it's now a magnetised chain. How could it have got magnetised? I never used a magnetic trainer, and the only magnet has been on my left crank for my older GSC10, and a spoke magnet.

Will changing the chain be a permanent solution ?

Well, it does seem bike related. Sensor is working on another bike, but thats a folder, so I can't put it on a trainer.

garmin cadence magnetless

Hi,
my garmin cadence magnetless rubberband doesnt fit the crank of 11speed dura-ace, should i force to fit it? just worried if i will just break it.. hope get info from other users.
thanks!

Hi,
my garmin cadence magnetless rubberband doesnt fit the crank of 11speed dura-ace, should i force to fit it? just worried if i will just break it.. hope get info from other users.
thanks!

You should have a choice of three rubber bands of different sizes, do none of them fit?

Hi, thanks for the reply.

Of the 3 of them, the biggest one still doesnt fit. already tried, seems very fit... but i havent tried forcing it due to fear of damaging the band.