High vibration power spikes... anyone else?

[rruff]

My Gen3 unit seems to be working well except for high-vibration issues screwing up the accelerometer sometimes. The roads are pretty rough around here, but my Gen2 never experienced this... not once... even bombing down gravel roads and 60mph descents on chip-seal. But the Gen3 has a some portion of high vibration and power spikes on nearly every ride. It wouldn't be a big deal if the software corrected for this after the fact... but it doesn't. Seems like it could though. We have the avg grade (from the barometric pressure) and speed, so it could calculate an average power when things go wacky. As it is the NP is greatly effected, but the avg power not so much. It is enough to pretty much screw up the file though, if you are interested in getting accurate values.

I'm wondering... does anyone else experience this? If I'm the only one then it wouldn't make sense to have a software fix.

[ChrisS]

I get power spikes as well. They usually show as 2000W or so. I have to go through all my files in excel to change them to some nominal value. One problem is that the spikes set the magnitude of the power axis on the graphs which means the 'normal' 200-250W range just looks like a stright line.

It would be useful if there was a way for the user to set the scale of the graphs.


Chris

[ldmitruk]

I've got the same issue in several files gathered with my GenII Aero. This usually happens when I go over a patch of rough pavement. As you can see in the graph below:

powerspike.jpg (85.29 KiB) Viewed 8597 times

At around 30 km I get a big spike for about 3 or 4 seconds, Notice I don't get the high vibration bars in the graph. When I checked the file in excel I found the elevation was remaining the same but the slope was jumping all over the place. As my ride was three laps around the course I know I encountered the same rough pavement, and got some more reasonable results. I tried to fix the slope data by bringing in more into "sync" with surrounding values by removing the value in front of the decimal point and then re-analyzing. However this did not work as the values got reset back to original by iBike. Any other suggestions besides deleting the offending values?

Cheers!

[rruff]

In an ideal world it should be fairly straightforward for the software to analyze the file, spot these places where the accelerometer has trouble, and apply a fix using the slope and speed data instead. I'm kinda surprised that it doesn't do this already, because it *does* apply a fix to correct for tilt... and the software seems to be able to locate the high-vibration areas most of the time, but it doesn't fix them.

[racerfern]

Once in a blue moon I get a hiccup like yours from exceptionally rough roads. Just like you edited the slope you can manually edit the wattage column by mimicking the surrounding data points.

I'm surprised a small spike like that would change your NP all that much. Removing the offending points changed your average from 178w to 177w.

[coachboyd]

If you place your cursor in the top number of the power graph (for example 2000 watts), you can manually change that number, hit enter, and you will change the max value the graph displays.

This is very useful if you do get a power spike.

[wellmt]

That's something useful to know

I've never had this problem. I've noticed another way to get wacky readings though when I was doing a test, if you put the iBike in the set-up/coast screen whilst descending it causes these 2000 watt spikes.

[racerfern]

That's something useful to know

I've never had this problem. I've noticed another way to get wacky readings though when I was doing a test, if you put the iBike in the set-up/coast screen whilst descending it causes these 2000 watt spikes.

I wasn't going to mention this but you're absolutely correct. Entering the setup area while riding can cause crazy readings for a second. Avoid entering setup while riding unless you must do so.

[ldmitruk]

It's not so much the change in my NP values, but effect it has in WKO+ when determining CP levels and watts per kg in the 1 and 5 second range. This makes it harder to get a handle on what I can actually put out.

Once in a blue moon I get a hiccup like yours from exceptionally rough roads. Just like you edited the slope you can manually edit the wattage column by mimicking the surrounding data points.

I'm surprised a small spike like that would change your NP all that much. Removing the offending points changed your average from 178w to 177w.

[rruff]

I've never had this problem. I've noticed another way to get wacky readings though when I was doing a test, if you put the iBike in the set-up/coast screen whilst descending it causes these 2000 watt spikes.

That's funny... I do that pretty often and I've never noticed this.

[berveling]

I get high power spikes on about 1/2 my rides, and high speed spikes on about 1/5th of the rides (I do not believe that I can ride at 320km/hr!). I have not investigated their cause. I just delete them through the Excel worksheet (I check their time on the graph page and then go to the Exel page and replace them with a nominal value). They don't seem to affect my NP much, but they do affect the Mean Maximal Power curve in WKO+.

[rruff]

I've never experienced a speed spike... seems like that would likely be a sensor or electrical interference issue. Do they occur at the same time?

As for the power spikes, it looks like the accelerometer gets confused. There are two different ways to determine acceleration with the iBike, though. One is to use the accelerometer data, and the other is to use the speed sensor and slope data (avg slope via static pressure). These are independant and can be used to check each other. It would be a good feature to have in a revision to the software.

[berveling]

When I get a speed spike, it is invariably simultaneous with a power spike, but speed spikes occur much less frequently (ie I get power spikes on their own!). I'm not bothered by the spikes - the whole system is too good generally to worry about some peripheral issues which are easily removed.