PowerTap Recalibrates with New P1 Pedal and C1 Chainring Power meters

Wow, $700 for a complete chainring-based power meter looks like a potential game-changer!

Correction: easily replaceable* as obviously the rings are replaceable but the rings are non-standard.

The chainrings are replaceable. You just have to use the specially made FSA chainrings. If you switch to a different model chainring, say from 52-36 to 50-36, you need to send your power meter back for recalibration.

@Myke I think it’d have to be chainring based. Size/Thickness is too critical for MTB pedals and MTB pedals are generally thinner than road pedals. A direct mount chainring+powermeter for SRAM or Cinch cranks would be super sweet though.

no, dont stick to hubs. i like what youre doing here. one way or another, power will be measured on your bike.

No 4 bolt road option is rough, plus not being able to swap chainrings easily. The data quality is surely better than a Stages but only enough to matter for a smallish portion of users – especially the users at that price point. Pedals look like possible hot stuff, but reduced cornering clearance will have to be well reviewed before I’d put any money on them. Crits are already sketchy enough.

Interesting model, they claim elsewhere they still believe the hub is the best place to measure power (it probably isn’t) so this is adding products, not an improvement in power measurement or advancing technology. Does this mean they don’t actually think the hub can compete with the newer pedal and crank systems coming to market. At some point somebody will put the rings and pedals on one of the crank systems and get three different numbers. Four if they run a hub at the same time! Then what? If Powertap devices don’t all read the same their credibility gets a knock. Will be interesting to see how competing with themselves as well as the other alternatives works for them.

@Rye. that’s bollocks. accuracy is accuracy. The guy with the hub/pedals/trainer is right to expect the numbers to be the same. How does he train and improve if they are different? Which one is his true ftp? which one will tell him if he’s redlining on a climb?
What you are saying is that it doesn’t matter what numbers any device is showing. I know that nobody will actually ride with multiple devices but they make claims of accuracy. So is it or isn’t it? Does it measure accurately the power input of the rider? If it does then all devices of the same accuracy will show the same. I can assure you coaches with multiple athletes, teams and even anybody wanting to take part in power pissing competitions on Strava need true accuracy and repeatable data. If Powertap offer multiple devices and claim they measure power input accurately regardless of how and where they do this measurement the numbers should be the same.

Tyler: I asked PowerTap this exact question last fall because I am sick and tired of waiting around for an option for my disc CX bike (that I use also as a road racing bike in summer). The short answer was: “not soon”, owing to clearance / tolerance issues of having to fit stuff into the hub shell. Also even their 160mm hub uses a proprietary rotor, which sucks; I’d rather use my centerline rotors, thanks.

The chainring solution is one that I’d want, but the having to send back to the factory for recalibration is a showstopper. I’m already swapping from 46/36 in CX season to 50/34 in road season.

What I really want is a crank or spider based option that broadcasts ANT+ and Bluetooth LE/Smart, and can be used on carbon cranks (because I don’t want to ditch my very nice S-Works crank just to install a Stages). Quarq doesn’t broadcast Bluetooth LE, which IMO means it’s not future-proof against upcoming apps for smartphones, wearables, etc…, SRM is mad expensive and no one else has the configuration I want.

I recognize I’m a minority use case here, but this is why I once again won’t be buying another power meter this year until all of these questions are worked out.

@alvis: Even if the three power meters from PowerTap are perfectly accurate and have equal precision, they will not read the same because they are each measuring power at a different point in the drivetrain. Once you throw in the other factors that cause power readings to vary–individual differences in strain gauges, differences in otherwise identical cranks, and etc–expecting identical results from multiple power meters is foolish. All of those uncertainties and differences add up to the uncertainty in the measurement that a given company claims for a given power meter.

What a rider should expect from a power meter is good accuracy and excellent precision.

thanks Tyler, that’s worth a look. I’d still much rather find an elegant, integrated crank solution since my primary CX bike now serves as my road bike / road racer, too, and I already have 3 wheelsets for it.

The chainring based system from PT was exciting, but I need to be able to swap rings without sending it back to the factory.

Sure they will, if lead blocks only feel 150g or so heavier than other blocks.