Powertap C1 Opinions

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stevecassidy
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Powertap C1 Opinions

Postby stevecassidy » Wed Dec 21, 2016 9:14 pm

I'm considering a power meter purchase and the Powertap C1 looks like an attractive option. The few reviews I've seen online look positive, it's just a bit more costly than Stages but offers dual sided power readings. At the moment I'm a little interested in having a left-right balance reading as I'm trying to correct a weakness in my left side. I realise the C1 will only give an approximation of balance but it might be useful in seeing gross differences.

Does anyone have first hand experience with the C1? Any information is welcome.

Steve
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Re: Powertap C1 Opinions

Postby stevecassidy » Thu Feb 02, 2017 8:22 pm

Interesting that there was no response to this, it seems that this is not a popular option. I just picked one up from probikekit at a good price ($760 or so), it arrived yesterday so I thought I'd give a first impression.

The C1 requires a 110mm BCD crank to fit to and since I have a regular Ultegra 6700 group I needed a replacement crank. I picked up a cheap 105 5750 crank for $121 thinking that the weight difference with Ultegra was not likely to be too much. I weighed everything as I switched it over and interestingly found that the left crank arm on both groupsets was identical in weight at 198g. The right side showed some differences with 6700 coming in at 509g with rings while the 5750 was 528g, so I'm gaining around 20g with the 105 option (but saving around $80).

With the C1 chainrings fitted the right side crank weighs in at 694g so an extra 166g over the regular rings and 185g for me over my Ultegra 6700 groupset.

I had a ride this morning on the trainer. The C1 paired first time with my Garmin 500 and prompted me to calibrate. I got the kind of power readings I expected, I'm not very fit at the moment but did most of a Sufferfest video managing about 230w for the 'tempo' sections. It will be good to look at the numbers as I gather more data and begin to learn about training and riding with power.

Steve
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Re: Powertap C1 Opinions

Postby dalai47 » Fri Feb 03, 2017 12:25 pm

Nice. Look forward to your long term review after you have had it a while!

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Re: Powertap C1 Opinions

Postby stevecassidy » Wed Apr 26, 2017 5:53 pm

Well I was planning on writing a bit more of a review after a few months riding with the C1 but as of this weekend it's given up on me.

After riding on Friday I gave the bike a wash. On Saturday I was getting nonsense power readings from the C1. I tried a calibration and it gave me "Calibration Failed". When I got home I tried a new battery to no avail.

I've reported this to Powertap and had an email response in reasonable time with some suggestions. They didn't work so I'm now waiting on their response. Probikekit have also responded saying that they'll handle it as a warranty claim if needs be. So at least I'm getting responsive service from both.

Will post with more detail when this gets resolved.

Steve
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Alex Simmons/RST
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Re: Powertap C1 Opinions

Postby Alex Simmons/RST » Thu Apr 27, 2017 6:33 am

Good luck with it. Just don't go making training interventions based on the pseudo-power balance data.

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Re: Powertap C1 Opinions

Postby stevecassidy » Thu Apr 27, 2017 8:15 am

Alex Simmons/RST wrote:Good luck with it. Just don't go making training interventions based on the pseudo-power balance data.
All the balance numbers I've looked at show I have no significant imbalance - everything hovers around 50%. So that has gone out of the window as something to worry about.

Steve
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Re: Powertap C1 Opinions

Postby Alex Simmons/RST » Thu Apr 27, 2017 8:27 am

stevecassidy wrote:
Alex Simmons/RST wrote:Good luck with it. Just don't go making training interventions based on the pseudo-power balance data.
All the balance numbers I've looked at show I have no significant imbalance - everything hovers around 50%. So that has gone out of the window as something to worry about.

Steve
They show a pseudo-balance which hovers around 50:50, which tells you very little about your actual pedal balance or the manner in which that pseudo-balanced was achieved.

To explain with an example, these pseudo-balance measurements (also on Power2Max and Quarq) cannot tell the difference between these pedal force scenarios for say the left downstroke portion of the crank revolution:
110L : -10R
100L : 0R
90L : +10R

since they can only report the net value from both cranks, even though these represent quite different pedalling force scenarios.

It's entirely possible that a pseudo-balance meter can report you to be right side dominant, while at the same time a power meter measuring each crank (or pedal) independently reports you as left side dominant.

Even if it showed a pseudo-imbalance that hovered around 47:53, what then?
It's just not actionable intelligence. Asymmetry is normal and variable asymmetry is normal. That wouldn't be something to worry about either.

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Re: Powertap C1 Opinions

Postby Comedian » Thu Apr 27, 2017 3:48 pm

Alex Simmons/RST wrote:
stevecassidy wrote:
Alex Simmons/RST wrote:Good luck with it. Just don't go making training interventions based on the pseudo-power balance data.
All the balance numbers I've looked at show I have no significant imbalance - everything hovers around 50%. So that has gone out of the window as something to worry about.

Steve
They show a pseudo-balance which hovers around 50:50, which tells you very little about your actual pedal balance or the manner in which that pseudo-balanced was achieved.

To explain with an example, these pseudo-balance measurements (also on Power2Max and Quarq) cannot tell the difference between these pedal force scenarios for say the left downstroke portion of the crank revolution:
110L : -10R
100L : 0R
90L : +10R

since they can only report the net value from both cranks, even though these represent quite different pedalling force scenarios.

It's entirely possible that a pseudo-balance meter can report you to be right side dominant, while at the same time a power meter measuring each crank (or pedal) independently reports you as left side dominant.

Even if it showed a pseudo-imbalance that hovered around 47:53, what then?
It's just not actionable intelligence. Asymmetry is normal and variable asymmetry is normal. That wouldn't be something to worry about either.
I have vectors which are true double sided. They show a slight imbalance for me at high power outputs. I'm really not sure what can be done? What options are there?

And re the C1... I hope to learn more about this as I reckon they are a great idea. Powertap hubs are virtually bulletproof so I'm pretty interested.

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Re: Powertap C1 Opinions

Postby MichaelB » Thu Apr 27, 2017 3:56 pm

Alex Simmons/RST wrote: ...Even if it showed a pseudo-imbalance that hovered around 47:53, what then?
It's just not actionable intelligence. Asymmetry is normal and variable asymmetry is normal. That wouldn't be something to worry about either.
Shortened for brevity.

I love Alex's comments arouynd power meters and the reality behind them. It does make my head hurt sometimes in trying to understand the details, but one thing really stands out for me though.

Unless you are going to use the data properly (analyse and react to), they are nothing more than a toy which can decarease your enjoyment of cycling 8)


Therefore, I'm saving my money for the next bike or trip OS :mrgreen: :mrgreen: :mrgreen:

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Re: Powertap C1 Opinions

Postby macca33 » Thu Apr 27, 2017 5:13 pm

The only off-putting aspect for mine, is the limited compatibility of the C1 system - very limited....
CAAD10 Berzerker & Focus Mares & Ridley Noah SL

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Alex Simmons/RST
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Re: Powertap C1 Opinions

Postby Alex Simmons/RST » Thu Apr 27, 2017 5:36 pm

Comedian wrote:I have vectors which are true double sided. They show a slight imbalance for me at high power outputs. I'm really not sure what can be done? What options are there?
Are you asking how to test the validity of the data, or whether your pedalling data suggests an intervention is something worth considering?

As I said before, asymmetry is both normal, as is variable asymmetry. Attaining symmetry isn't the aim, improving performance is. There's nothing really to suggest one is related to the other.

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Re: Powertap C1 Opinions

Postby Alex Simmons/RST » Thu Apr 27, 2017 5:38 pm

macca33 wrote:The only off-putting aspect for mine, is the limited compatibility of the C1 system - very limited....
Which I suppose is why Powertap offer options for pedals, chainring and hub based power meters, since no one system is perfect for every use case.

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Re: Powertap C1 Opinions

Postby foo on patrol » Sat Apr 29, 2017 5:44 pm

I just wish that I could find someone to give my Powertap wheel to, because it's not talking to the head unit. :( It's one of the first Cyclopes ones, so has a cable from the sensor to the head unit.

Foo
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Re: Powertap C1 Opinions

Postby Alex Simmons/RST » Sun Apr 30, 2017 7:06 am

foo on patrol wrote:I just wish that I could find someone to give my Powertap wheel to, because it's not talking to the head unit. :( It's one of the first Cyclopes ones, so has a cable from the sensor to the head unit.

Foo
Model no longer serviced AFAIK but check with Powertap as they do (or did) offer an upgrade program for those with older model units. No idea if it's available here in Australia though.
https://www.powertap.com/post/blog-why- ... -gen-2-hub

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Re: Powertap C1 Opinions

Postby foo on patrol » Sun Apr 30, 2017 10:06 am

Thanks, Alex. 8)

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Re: Powertap C1 Opinions

Postby stevecassidy » Fri Jun 30, 2017 9:51 pm

Well, it's back. After almost two months I have the power meter back on my bike. PBK sent it off to Powertap who took their time to follow up the warranty claim. I didn't get any word from them apart from replies to my weekly queries, the last one was last week when they said it was on it's way - it arrived two days later. So they had sent it off without notifying me. So, not too impressed with the PBK service although they did do the right thing.

Anyway, back to riding with power on a new device. Fingers crossed that this one lasts a bit longer.

Steve
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