Powertap C1 Chainrings

Powertap C1 Chainrings Info

A way to install a power meter on standard cranks.  Many have dreamed this.  PowerTap’s  C1 Chainrings do just that.  They are limited to working on most five-arm compact (110mm bolt circle diameter) double-ring cranks, but that includes most cranks sold on road bikes today.  It’s a simple, relatively inexpensive solution that helps bring power to the people.

The chainrings are sold as a specially-machined set that are attached to five strain gauges, and a battery-powered transmitter that sends ANT+ and Bluetooth Low-Energy (BTLE) signals for head units, smartphones, tablets and computers to pick up.  Most cycling computers these days read ANT+, most phones, tablets, and computers read Bluetooth, so you probably already have the capability to get power data (and, by extension, cadence).  The signal also sends data on your left-right balance.

The rings are manufactured by FSA to PowerTap’s spec.  There are three ratios offered: 53/39 (traditional road), 52/36 (mid-compact), and 50/36 (compact).  They don’t do a 34 inner ring because they couldn’t get the rings to fit on all 110mm spiders.  The rings are mounted to the strain gauges and transmitter, the unit is bolted together, and then you mount the entire unit to your cranks after you remove your old rings.  Easy-peasy.

The setup is light: only 156g more than A set of SRAM Red chainrings, amongst the lightest on the market.  The battery is a simple 2032 coin cell, one of the easiest to find: you can find them in most convenience stores in addition to supermarkets, drug stores/pharmacies, as well as electronics shops.  The battery is sealed in a water-tight case that is secured with two bolts with 2.5mm hex heads.  The battery should last for about 200 hours of riding.  The hardware includes an accelerometer, so you don’t need a magnet to turn the unit on.

As with all crank-based powermeters, it’s wise to manually auto-zero the offset before each ride.  All the same the C1 has an auto-zero feature where it automatically checks and zeros the offset while you’re coasting to keep the numbers as accurate and consistent as possible.

The rings come with the battery, five chainring bolts, five contoured nuts, a quick-start guide and an ANT+ identification card.  The bolts should be tightened to 11nm-you thread the bolts from the inside and the nuts go on the outside.  It is recommended you remove the crank before installing.  If you ride so much, you’ve worn down the rings, they can be replaced.

The product is covered by a two-year warranty and top-notch customer service.

The PowerTap C1 Chainrings bring power to your cranks.