power spikes

Discuss light weight issues concerning road bikes & parts.
are
Posts: 135
Joined: Fri Sep 05, 2008 1:15 am
Location: Los Angeles

by are

I recently got a p2m NG and it's paired with a garmin 520. It's my first power meter (not counting the Wahoo Kickr). On every outdoor ride I'm getting at least one or two instances of bad data with my power reportedly spiking up to 10k+ watts. I can fix the .fit file, but it's a bit of a pain. Where is the problem most likely? As I start down the path of problem solving, is the problem more likely to be with the Garmin or the p2m?

Thanks!

pdlpsher1
Posts: 1484
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

This is odd. So are you seeing the 10k+ watt value in the .fit file? The 520 wouldn't display such a high value. I don't think the 520 is the culprit. I havd one and it's very reliable when paired up with my Quarq. On those spikes is the cadance normal?

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ergott
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Location: Islip, NY
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by ergott

Are you pairing via ANT or bluetooth? I'm not sure you can choose which, but from my experience ANT is more reliable then bluetooth.

morganb
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Joined: Wed Mar 15, 2017 5:30 pm

by morganb

This happened to me with the original battery but went away after I changed to a new one.

are
Posts: 135
Joined: Fri Sep 05, 2008 1:15 am
Location: Los Angeles

by are

I connected the p2m via ANT+ to the garmin.

I don't know about the cadence ... I need to check the source file. It's correct that I don't see it on the Garmin, I only see it afterwards when the file is uploaded to Garmin Connect. I have crazy high NP and TSS for these rides because there will be a few random spikes of huge power.

I did just re-look through the p2m manual and it only measures up to 3k watts, so I can't imagine where the Garmin is getting the number. A ride this weekend had a 19,980 watt spike.

Also, during the week, I do a bunch of trainerroad rides, so I connect the p2m to my computer using Bluetooth. I haven't gotten spikes these, but trainer rides are very different from outdoors.

re: the battery change ... change the battery of the p2m NG or the Edge? In either case it'd be a pain.

pdlpsher1
Posts: 1484
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

Just a thought. Since the NG is dual ANT+ and BT capable, I wonder if you can take your laptop along for a short ride. Put your laptop in a backpack or something. This way you can rule out the Garmin as a culprit.

TurboKoo
Posts: 427
Joined: Wed Oct 29, 2008 7:55 pm

by TurboKoo

I also get power spikes on my Stages. These always come on my mtb or cyclocross. Looking at file after ride it’s always rocky downhill and cadence spike causing ~2000w for me.
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zirxo
Posts: 156
Joined: Wed Mar 19, 2014 12:46 pm

by zirxo

I had this problem after the firmware update.
It seems as if Garmin units can handle the torque info from the power meter.

Disable the torque broadcast and it should be back to normal.

are
Posts: 135
Joined: Fri Sep 05, 2008 1:15 am
Location: Los Angeles

by are

Do you have a pointer re: disabling the torque broadcast? That sounds like a likely culprit.

I will connect my phone via bluetooth and try logging an outdoor ride that way, too.

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jekyll man
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by jekyll man

to disable the torque, access the pm using the android app, i presume how you updated it.
Seems to fix it.

Sorry, i cant help further, i just saw what others have done on slowtwitch with the same problem.
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zirxo
Posts: 156
Joined: Wed Mar 19, 2014 12:46 pm

by zirxo

Yeah, you need to use the Android app.
I got the advice from Power2Max after contacting them with the same problem.

nismosr
Posts: 1023
Joined: Mon May 05, 2008 5:15 pm

by nismosr

oh wow what a coincidence I have a NG Eco, this passed weekend on my way up to BM here in NY, I look at my Garmin 820 and my power is at 1025 watts at normal pedalling then went to 2k watts at one point. then went dead zero no responding, recalibrate it same thing .. after the ride look at my data on Garmin Connect my max watts was 6K watts woot woot lol .. contacted P2M and was told try to update my firmware .. not my p2m was only 3 months old. I will try it again this coming Saturday.

AndreLM
Posts: 263
Joined: Tue Feb 05, 2013 11:53 pm

by AndreLM

Interestingly this happened to me twice in the past few months... different bikes, different P2M’s, same Garmin Edge 520.

First one with a TypeS (2502W), second with an NGEco (65470W!!!). It was a 1-second power spike, and both right after I re-started to ride after a short brake.

It did not happen again, so I did not bother trying to track the problem down (simply fixed the .FIT file in GC).

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are
Posts: 135
Joined: Fri Sep 05, 2008 1:15 am
Location: Los Angeles

by are

65k watts is pretty good! I only got up to 19k. Amazing how such a short, high spike can mess up TSS for the whole ride.

billspreston
Posts: 367
Joined: Tue Jun 30, 2009 7:40 pm
Location: CA

by billspreston

I'm having similar spikes up to as high as 8k watts on a newly purchased Quarq Dzero. I figured it was the Quarq, but I'm using the Edge 520 as well and noticing a pattern in this thread...

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