Feel the power.
Ceramic Speed bearings are said to be the lightest, smoothest, and most durable bearings on the market. When you read about pro teams replacing stock bearings with ceramics, Ceramic Speed is the company they rely on. These bearings are hybrid ceramic, with steel races and rounder-than-round ceramic balls. They're the ne plus ultra of the bearing world and are the upgrade that transforms the PowerTap G3 Wireless Hub into the G3C Wireless Hub. They run smoother, and they shave 10g off of the total weight of the G3 rear hub.
G3 is short for Generation Three. Much like the G2 hub, this one chops a prodigious amount of weight off the previous version, but it does much more than that. The G3 design looks like a conventional hub, with a Matte Black finish and smaller diameter that masks the hub's purpose. This is only the most obvious of the changes. A much bigger deal is the new electronics configuration. They're now attached to the left hub cap rather than to the hub body, and they're able to be serviced without sending back the hub or rendering it useless.
That the brains of the hub are able to be serviced without sending back the wheel is huge. Just about every single powermeter ever produced, whether it's a hub, crank, or a pedal, it needs to be serviced at some time over its operating life. Until now, you've needed to give up your precious meter for days, or even weeks, to get it worked on and returned. We've witnessed power fiends get despondent and desperate, trying to figure out how they can source a spare powermeter for the duration of the absence. Now, you're able to get a spare cap with all of the electronics before you send yours in. And shipping is simpler and cheaper when you don't have to stick a wheel in a box.
Another improvement that comes with this change is a single CR2032 watch battery powers the transmitter. These batteries are easier to source and replace than the two 357 batteries found in the older hubs. The battery should last for approximately 300 hours of riding.
The hub has eight strain gauges inside the "torque tube," which is what measures power inside of the hub. This means that it still has the impressive +/- 1.5% accuracy of the older hubs. It still transmits an ANT+ signal, so any computer head unit that reads the signal is able to translate it into power, speed, torque, and virtual cadence.
The PowerTap G3C Wireless Hub is available in the color Black and with spoke drilling for either 20, 24, 28, and 32 spokes. The spoke hole diameter is 2.5mm, so it's compatible with conventional round, double-butted, and most modern oval-bladed spokes. The flange diameter is 57mm on both sides. The hub center-to-flange measurement is 38mm for the non-drive side and 17.4mm for the drive side. It's available with either a Campagnolo or Shimano/SRAM compatible freehub body. Should you purchase a wheel and need the other style, be aware that they're able to be swapped easily. After switching freehub bodies, the wheel will not need to be re-dished. The hub rolls on a 15mm-diameter aluminum alloy axle. Along with the hub, you'll get user instructions and the special tool for the end cap on the hub.
Please note that the G3C Hub does not come with a skewer.