Intermittent Speed and Power reading issues

[rstrom]

Hello,

I recently sold my Trek Madone which had the Duotrap sensor mated to my iAero with the GT firmware key. I've now installed the iAero back on my other bike which has the standard speed and cadence sensors. All the sensors seem to be pairing with the iAero but I think that there might be an issue with the way that the data is being received / interpreted because I'm seeing some huge intermittent speed reading errors (I've replaces ALL the batteries), especially when going downhill. I saw a max speed of 80mph on my ride today (the max I've ever done on this descent has been about 40mph). The ride had two minutes with an average speed of 53mph and an average slope of -2.34% - I'm going to go out on a limb here and say that is impossible!!!

The speed sensor is mounted on the non-drive side seat stay and the cadence sensor is mounted on the same side chain stay. The speed magnet passes in close proximity to the cadence sensor. Is it possible that the speed sensor is sending another signal to the cadence sensor in certain situations and that the GT firmware is doing strange things with the signal? Duplicating the speed signals?

Is there a setting in the unit to tell it that you no longer are using a single sensor that sending both signals?

Two ride files where I had this happen (today's much more prevalent than the previous ride).

Thanks,

Robert

[rstrom]

One last thing ... is there any way to fix these errors?

I've tried the repair speed spikes and that doesn't really fix it. I could go into the .CSV file and do LOTS of manual editing but I'm not really looking forward to doing that.

Any and all suggestions will be appreciated.

Thanks,

Robert

[Velocomp]

Please post a photo showing the location of your sensors and of your spoke magnet.

This is not related to your duo trap sensor; if you see "SPD FOUND" then your speed sensor is working.

It might be that your speed sensor is defective; as a test, you can swap-out your speed and cadence sensors (that is, turn your cadence sensor into a speed sensor and conversely, then pair again) to see if this solves the issue.

[rstrom]

I road today with the cadence sensor removed and it made no difference.

Here are the pictures that I believe show you what you wanted to see.

I have also switched the locations of the two sensors (changing the settings internally so that they are configured for the desired function) and paired the unit with the new sensor configuration.

I will ride with this tomorrow and see if it makes any difference.

Robert

[racerfern]

Can you move your speed sensor way down the seat stay, say to the word "IN". Obviously move the magnet so it lines up and then go for a ride.

I see the two magnets so close in proximity that they're interfering with each other.

[Velocomp]

Swapping sensors will tell the story...

[rstrom]

Well I "think" it might be fixed. Not totally sure or convinced yet but today's ride has no huge unexpected speed spikes or huge totally insane power numbers like several previous rides. Today's ride was also much flatter than the past two days that showed the 50 and 70mph descents and even 67.2mph on an ascent where I was cranking out 1629w (just call me Mark Cavendish ). In all previous rides where I noticed this behavior it definitely really seems to show itself on the descents where speeds are in the high 20's and above. The two previous rides had almost 2000' of climbing and descending; today's ride only had 449.

Hopefully it's fixed, but I won't declare victory until I get a few more rides without issue and at least one with some significant climbing and fast descending.

I have no real idea what fixed it since I swapped the sensors, moving the one that was the speed to cadence and vice versa and moved the speed sensor quite a ways down on the seatstay so that the path of the speed magnet was quite a distance from the cadence magnet (their paths were close to crossing before).

Thanks for the advice!

Robert

[rstrom]

One more thing .... any suggestions on the easiest way to fix the previously messed up files to something reasonable?

Thanks,

Robert

[rcmaps]

I sometimes get "messed up" Heartrate recordings up to 200+ bpm usually when going downhill. It's really annoying. Only way is to open the csv file in MS Excel, put on filters on the headings and filter out the high readings and replace it with more reasonable figures, then save it as csv file.

That file should re-open it in iBike software without any problems.

[travispape]

I sometimes get "messed up" Heartrate recordings up to 200+ bpm usually when going downhill. It's really annoying.

By the way, that is a common problem especially on cooler, less humid days. Your jersey is flapping in the wind and building up just enough static electricity to interfere with the sensor. Try squirting your jersey with water from your bottle next time to see if it makes a difference.

Travis

[rcmaps]

I sometimes get "messed up" Heartrate recordings up to 200+ bpm usually when going downhill. It's really annoying.

By the way, that is a common problem especially on cooler, less humid days. Your jersey is flapping in the wind and building up just enough static electricity to interfere with the sensor. Try squirting your jersey with water from your bottle next time to see if it makes a difference.

Travis

Yes, I have noticed that - although "jersey flapping in the wind" is relative - I have a tight fitting merino wool long sleeve shirt underneath and a polyester short sleeve high viz cycling jersey/T-shirt as the out layer (it's still winter here and I'm riding between 9-13 deg C) - you'd think flapping in the wind should be eliminated but it is still enough to cause these wild swings in readings. Sometimes, the wild readings only occur at the beginning of a ride (when I'm relatively perspiration free) and the readings becomes more consistent later on. However, lately it's a little unpredictable. I do find if I stopped and squirted water down my jersey as you suggested it helps but after a while couldn't be bothered to stop at the bottom of every incline!

BTW, I tried some ultrasound gel on the electrodes on my last ride and was hoping that this will eliminate the issue. However, it had the opposite effect whereby every time I descended I noticed the high readings.

There may be an issue with wool and polyester rubbing on each other creating even more static electricity especially in windy situations on descends - but I did remember in summer when I only had on my polyester jersey the same problem occurred.

[rstrom]

I've now ridden enough rides without any of the previous hugely increased speed (causing hugely increased power readings) to declare that it's fixed.

I'm not really sure what the exact fix was but I don't think it was switching the sensors. I think it was probably moving the sensors so that they were not as close to each other and the magnets did not did not pass by each other so closely. It makes no sense to me that switching the sensors would be anything but a troubleshooting step. If the speed sensor was bad and was switched to a cadence sensor then the cadence sensor should now be bad - that does not appear to be the case.

This bike was setup with the sensors in the original configuration (see pictures) and was ridden without any issues that I remember before me switching back to it recently (it's been a year so my memory could be wrong).

The new configuration has the cadence sensor in the same location and the speed sensor near the IN of the words "Made in USA" on the seatstays (I think it's a little lower than that).

Thanks,

Robert