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Powertap P1 problems
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My Stages PM died and my friend let me borrow his P1s for a race this weekend. I had planned to buy some P1 later this year, so this would be a good test run.

So I installed them on my bike and paired them with my Garmin 520. P1 batteries are good, and both LEDs flash green once, which means the right is paired with the left and all is good. I calibrated them and then went out for a test. But the 3s power simply ramps up to my current power, then backs down to 0, then back up to my current power, then back down to zero. As it rampes down to zero, it also moves to a 100/0 L/R balance.

I've gone on three separate 10 minute rides, and this just repeats. I changed the batteries, and swapped out my disc wheel for my trainer, even took the pedals off and put them back on, and no change.

Has anybody else had this issue? Any ideas?

From P1 owners I've talked to, and from DCR's review, these are supposed to basically just be plug & play.
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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I've not seen that issue with mine.

If I have any issues its that during a recent Duathlon they paired when I got on the bike but wouldn't show any power. In fact thinking about it the problem seemed very mich like the ops.

Other than that they've been great - do need to calibrate them every ride it seems though.

I ride:
Cervelo - P-Series/R3
GT - Sensor Carbon Expert

Supporters - Flo Cycling, Mount Bikes
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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Just yesterday at about 72 miles into a 82 mile ride I got abnormally low power readings, and the rest of the way home the power would jump all over the place and my L/R balance was dorked up. When I got home I immediately changed the batteries. This morning, everything was great for the first couple of hours of a 56 mile ride. Then, on the way home, in literally the same exact location as yesterday (10 miles from home, within 1/4 mile of yesterday's event), it went haywire again, with 0/100 readings, or simply '---' for L/R balance, then jump to things like 20/80, 30/70, etc, eventually evening out and then bonkers again. Makes me wonder if someone bought a new wifi transmitter that has a little too much power and the ANT+ got interfered with.

BTW, looking back through some power files, the only other time I've seen this was the first day I rode the pedals - Jan 5 of this year. The first 13-15 minutes were plagued with this, and then it settled out. The P1 manual does have this to say

Quote:
INDEXING PROCESS
Each time the pedals are initially installed there is a one time indexing process that occurs during the first few minutes of pedaling (basically the pedals are finding where the pedal axel has been positioned in each crank arm). During this time the Power and Pedal Balance output will not appear accurate, typically reading low. There are two versions of this process--the long version and the short version. The long version occurs when you install the pedals and immediately begin to ride the bike. The “finding” of the index will typically take between 3 and 5 minutes of continued pedaling to complete.
Monday is a recovery day, so it will be re-pairing, followed by "reactivating" the sensor, zeroing, and riding to see if things settle out.
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Re: Powertap P1 problems [tigermilk] [ In reply to ]
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Yeah, I read about that indexing, which is why I did each ride for at least 10 minutes, waiting for it to index. 35 minutes of riding later, the numbers remain useless.

I'm a bit miffed. My Stages, for all its faults as left-leg only, worked flawlessly every ride for nearly 3 years.
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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I would just call Saris.....they have awesome customer service
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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Did you set the crank arm length on your 520 correctly ?
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Re: Powertap P1 problems [rmg] [ In reply to ]
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rmg wrote:
Did you set the crank arm length on your 520 correctly ?
Yes, it was already set to 172.5.
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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I'm assuming you didn't have a 910/920 on your wrist that was sending out a different crank length, or possibly have it also paired with a phone sending out different crank lengths?

Failing that, I once had that sort of problem and it was resolved by recalibrating both left and right pedals using the bluetooth app on the iphone. I've had virtually no problems in a year of riding. Definitely give Powertap a ring.
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Re: Powertap P1 problems [rmt] [ In reply to ]
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rmt wrote:
I'm assuming you didn't have a 910/920 on your wrist that was sending out a different crank length, or possibly have it also paired with a phone sending out different crank lengths?

Failing that, I once had that sort of problem and it was resolved by recalibrating both left and right pedals using the bluetooth app on the iphone. I've had virtually no problems in a year of riding. Definitely give Powertap a ring.
No other Garmin or phone. I don't have an iPhone, so apparently I couldn't connect to it even if I wanted to, it seems they still have no Android app.

I'll give them a call.
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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I returned mine and received a new set. Mine had all sorts of problems - battery drainage, balance, pairing, you name it. Hopefully the new ones work better, but I'm actually considering selling them rather than using them.
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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I also had lots of issues with P1's - mine was first a powerspike issue - 30k watts for just a split second - but long enough to skew the average power figures for every ride. Many other people had the same problem, including DC Rainmaker.

This issue was meant to be updated with new firmware, but with mine there was a problem installing the new firmware through the app, one pedal updated first time, BUT the other totally refused to update, leaving me with one pedal on new firmware and one with old - a mess.

Ultimately the UK distributor replaced the pedals. Whilst I do still get the error message saying the right sensor won't connect (but despite this I do get data from both ok), but other than this ongoing irritation, so far so good with the replacements.

But it does seem to me that the P1's are suffering too many teething issues - best for new buyers to wait for version 2.
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Re: Powertap P1 problems [Chri G] [ In reply to ]
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I have had mine since day one with 0 issues... js

The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev
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Re: Powertap P1 problems [LuisDF] [ In reply to ]
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I talked to PT support, and they suggested it was a line of sight issue with my Garmin 520, so basically all data was not getting to the Garmin. I've got my 520 on a K-Edge mount in between my aero bars, so I find that hard to believe. But I'll toy around with some different Garmin positions.


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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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mbwallis wrote:
I talked to PT support, and they suggested it was a line of sight issue with my Garmin 520, so basically all data was not getting to the Garmin. I've got my 520 on a K-Edge mount in between my aero bars, so I find that hard to believe. But I'll toy around with some different Garmin positions.


Well, I'm no rocket scientist and I didn't stay in a Holiday Inn Express last night, but...

While the "line of sight" suggest sounds plausible, it dawns on me that one's foot would always be between the P1 and a computer mounted on aero bars, making the P1 a poor choice for triathletes. I've got to be missing something here...

Power tap has been known for excellent customer service in the past.
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Re: Powertap P1 problems [mbwallis] [ In reply to ]
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FYI, after the weekend of wonky wattage readings late in the ride with 0/100 balances, my P1 appears to be working nominally. Easy ride last night, hard ride this morning of 90 minutes, no funky readings. The proof will be later in the week - is it a moisture related issue (it's the Houston area, it's hot, humid, and Saturday I dumped out about a gallon of sweat) or interference (went haywire on the same stretch of road Saturday and Sunday).

BTW, I don't see how it could be location of my computer (Joule GPS+) - it's been in the same position on my bike for weeks with zero issues.
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Re: Powertap P1 problems [tigermilk] [ In reply to ]
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Thanks. Last I night I confirmed it was not a computer position problem. I did a short ride holding my Edge 520 about a foot from the left pedal, and it did the same thing. I will try out another set of P1s tomorrow, to see if it's the pedals.
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Re: Powertap P1 problems [rmg] [ In reply to ]
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rmg wrote:
Did you set the crank arm length on your 520 correctly ?
Turns out this was my problem.

Did a Duathlon in training yesterday so had my 510 on the Garmin mount and 920 on my wrist.

The power readings ramped up, then back to zero and kept doing it. I stopped and recalibrated, nope still doing it. The. It hit me, my road bike has 172.5 cranks and my TT bike 170. It also turned out my 510 has bike profiles so the road bike was one setting - 172.5, and the TT 170. However on the 920 there is no bike profile setting so when changing bikes I need to change it, which I had t done.

Once I had changed it there were no more issues. Very pleased with that as they are an awesome power meter, especially for those of us with more than one bike.

I ride:
Cervelo - P-Series/R3
GT - Sensor Carbon Expert

Supporters - Flo Cycling, Mount Bikes
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