What Our Gearhead(R) Experts Are Saying:"I use the Rival E1 power meter on my road bike, and I love how stealthy it is. It installs like any normal crank, adds almost no weight, and still gives me reliable, consistent power readings without any fuss."Power should feel natural-not complex. With the Rival E1 DUB Wide Left Arm and Power Meter Spindle, SRAM brings hidden precision to your ride. The power meter is cleanly integrated inside the DUB spindle, keeping the drivetrain sleek and simple while providing accurate left-side power measurement that's used to calculate total output. Whether you're training or pacing yourself on a fondo, this minimalist design gives you the data you need without overwhelming your bike setup. Installation is just like any standard crankset, and with 400+ hours of battery life on a single AAA lithium cell, you're set for a full season of reliable performance. It's also IPX7 waterproof and less than 40 grams heavier than a standard crank, so you'll hardly notice it-until you look at your ride stats.