SRM drops speed/distance

[Zach-dk]

Something strange happend today on my trainingride. My SRM PCIV didn'nt read the speed correct. Underway the speed all the time went up and down from 1/4, 1/3, 1/2, 2/3 to actual speed (but never faster than actual speed). When I got home the distance recorded was around 2/3 of what I actual did. Seems like the PVIV dropped some of the reading or they got lost in transmission.
I stopped several times to check the speedsensor, the cable and the plug, but everything seemed OK. What can be the reason?

 

[Woofer]

Something strange happend today on my trainingride. My SRM PCIV didn'nt read the speed correct. Underway the speed all the time went up and down from 1/4, 1/3, 1/2, 2/3 to actual speed (but never faster than actual speed). When I got home the distance recorded was around 2/3 of what I actual did. Seems like the PVIV dropped some of the reading or they got lost in transmission.
I stopped several times to check the speedsensor, the cable and the plug, but everything seemed OK. What can be the reason?

Has this always worked, for how long?

The magnet and sensor need to be extraordinary close IMHO. A slight movement can make it record nothing for speed and distance or be intermittent ( or the same symptoms if the wheel is ridiculously flexible or the magnet is a bit loose and off). I usually tape the sensor in place and don't bother with zip ties ( this is what is recommended in the owner's manual. ) so the sensor will not move.

 

[Zach-dk]

I checked the sensor and magnet again. The magnet was exactly in the middle of the sensor - and superclose.
Then I moved the sensor a little up - maybe a millimeter. And now it looks like it works fine. Maybe the sensor is stronger in the end opposite where the wire is attached.

 

[Woofer]

I checked the sensor and magnet again. The magnet was exactly in the middle of the sensor - and superclose.
Then I moved the sensor a little up - maybe a millimeter. And now it looks like it works fine. Maybe the sensor is stronger in the end opposite where the wire is attached.

The optimal lateral position of the magnet in relation to the sensor is not where one would expect it to be as you discovered, consult the manual for details.