Borrowing a page from the asphalt, SRAM has just debuted the Quarc Quatro power meter crankset for mountain bikes. It’ll use the same basic interface between the crank arm and chainrings to measure how many horses you’re laying down.
The Quatro uses the lightweight X0-level carbon fiber crankarms and gets a user replaceable battery that’s good for a reported 400+ hours of ride time per CR2450 battery. It communicates via ANT+, making it compatible with Garmin, etc, and Training Peaks software among others.
There arenGXP and BB30 options, and the system mirrors the road setup’s +/-2% accuracy.
Weight is 814g with GXP bottom bracket, BB30 will be lighter. It uses their X-Glide chainrings and will have only 2×10 chainring options in 42/28 and 39/26 options. Available in October, pricing TBD.
Each unit spends 20 minutes under water before leaving the factory, so water crossings and mud shouldn’t be an issue.
For MTB, power measurements let you preride a course and see exactly what it’ll take out of you. It’ll also show you how much time is spent coasting versus pedaling. How you use that data is up to you, but it’s there for the taking.
Qalvin is their new iPhone app that talks to the cranks via ANT+ to let you calibrate the system from your PC. You’ll need an ANT+ dongle, available separately.