I have a C1 myself and I read that most any FSA chainring will work. I think the key is getting the bolts locked-tighted and torqued exactly even. Are you ever making a trip to Madison?

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Madison photographer Timothy Hughes | Instagram

If there's no guide, how's the bike shop supposed to do it?

Just get a Torx wrench and loosen everything up if you want to do it yourself. Are you buying the rings from Powertap already?

They used to recommend the FSA's that have the Powertap branding on them. Later I think they rescinded that.

The bolts are definitely T-30 with a plastic piece in the center to protect people from accidentally mucking with them. Not sure how those pop out? Maybe just pryed out with a tiny screwdriver.

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Madison photographer Timothy Hughes | Instagram

Yeah, three of my rubber/plastic things have fallen out anyway. Should be easy to remove.

Thanks for the help!

If the bolts are torqued properly (7 nm?) in a star pattern then recalibration shouldn't be needed? The PowerTap rep told me that the added benefit of sending it in (or I guess just buying a new one) is that they will recalibrate the unit after installing the new chain rings: https://www.powertap.com/service/chainrings.

I wonder what the difference is between that and the Zero Offset the mobile app does?

How many miles did you get out of the chainrings before deciding to replace them?

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Madison photographer Timothy Hughes | Instagram

That's a good question and I hope someone here knows the answer!

Almost 3 years with 22,500 miles (not including indoor training), I've tried to replace chains/cassettes as early as possible knowing that the chainrings are relatively expensive to replace.

Calibration and offset are two different things by definition. Think of it like a home scale. A properly calibrated scale will accurately recognize the difference in weight when you put a 25 pound item on it. But only if it is offset properly, meaning the starting value is 0.0 with no weight on it, will you get an accurate reading. If you properly offset an improperly calibrated scale, you will still get inaccurate readings. Just like if you have a properly calibrated scale that is not offset correctly. You need both.

Wow, sounds like you got your money's worth. It would like me about 11 years to put on that many miles, lol.

How is the C1 accuracy now? Do you have a smart trainer or anything you can gauge the power reading up against? Maybe borrow a friends PM pedals for a ride? Because if it's spot-on you shouldn't need to pay them $300 to tell you so.

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Madison photographer Timothy Hughes | Instagram

I have a C1 and have wondered about using FSA chain rings that I have on hand when it's time to replace them.

Using the method of placing 25 lbs of weight on a crank arm, could I measure what the Powertap chain rings read before taking them off and then install the FSA chain rings with the same 25 lbs on the crank arm to determine if the calibration is the same?

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Indoor Triathlete - I thought I was right, until I realized I was wrong.

I bought one in january 2017.
It broke down because of rain in June 2017 during a rainy day, IM without power. Powertap refused to discuss with me directly and asked me to deal with the website that sold me the unit.
I strugled and got one back in Nov 2017. It broke down in May 2018, IM without power in June again. My store told me it was impossible to send me a new unit before my A race.
I strugled to get one back, it only arrived 20th august.
I put it back on my bike with a surpise : the chainrings where oscilating right and left. Turns out they assembled it back wrong. So I dissassembled it and put it back the correct way ( what a joke, they can't screw correctly 5 bolts) with the same torque on evey bolt. Now the calibration always brings a random value between -10 and -20, and the power is 20 to 30W behind my Elite Direto.

So be careful before paying them 350$ for service. Because from what I have seen so far, the service is slow and inadequate. I have my third unit of this product, and at every race I did it was not on the bike because it didn't work. And I don't expect anything different will hapen for my A race this year. That said, it might only be powertap France's issue and not general at all. Or maybe I'm just very unlucky.

Following as I think the C1 Chainring is one of the few viable PM options for me.

Sounds good to me. I do something similar with the Powertap hub.

Mine too died in the rain. Luckily it dried out, put in a new battery and it's fine now.

Trying to do as much as I can on my own rather than send it back.

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Indoor Triathlete - I thought I was right, until I realized I was wrong.

I had 3 of them (original, warranty, warranty), all got killed with rain, and all seemed to magically come back to life after I dried the battery compartment out. I loved the powermeter, and it worked fantastically, except for this fatal flaw. Still hoping they announce a version 2.0, but until then I'm on a used SRM.

Just wondering if any 3rd party rings (given they would allow space for the pod etc.) Would work? There is a slight issue with the fact the rings mount to the rear of the power meter and therefore a spacer would be required between large and small ring.
Also can you mount larger rings without affecting the power calibration? If you use original rings or 3rd party

Sorry to revive an old thread, but I'd like to replace the rings on a C1 powermeter that I've come to realize that the chainring combo is constructed as a 1-piece unit. I've never come across chainrings like this before and I'm wondering if you ever found out if any other 3rd party rings could work. Any advice would be appreciated.