Gravel Power Meter: p2m NG G-X Rotor

The latest p2m G-X variant has been specifically developed for use with Shimano GRX chainrings and is compatible with both 1x and 2x drivetrains. The integrated battery offers a runtime of approximately 80 operating hours and can be conveniently recharged using the supplied charging cable. Dynamic calibration for an accuracy of +/-1% is part of the standard features, as is cadence measurement, along with the transmission of data on left-right balance and pedal smoothness to your bike computer.

NG G-X Rotor power2max-Edition

* The difference to the more expensive Rotor ALDHU crank is marginal. Apart from the fact that the original crank arms are completely CNC-machined, both cranks are technically on the same level.
** Only in conjunction with additional reducing sleeves, spacers, or specific bottom brackets.

The Rotor power2max Edition crankset is specifically designed for the Shimano Hollowtech II bottom bracket standard and can therefore replace a GRX crank without swapping the bottom bracket. The required spacers for BB86 Pressfit (86.5 mm frame width) are included, but for BSA 68, we still needed an additional 2-mm spacer in our case — luckily, we had one readily available in the workshop drawer.

Pro tip: Before purchasing, determine the required number of spacers or generally acquire a universal 24-mm spacer kit.

Before we begin the actual installation, it is recommended to update the firmware of the p2m NGeco power meter. The power2max app is available both in the Play Store for Android devices and in the App Store for iPhone. It can be used to register and configure various power meters, check their battery status, and keep the software up to date.
We connect to the device via Bluetooth, register the corresponding serial number (found on the spider, on the sticker, and on the box) along with the registration code (found on the sticker), and update the firmware to the latest version.

Before disassembling the Hollowtech II crankset, we remove the pedals, as this is easier to do while the crankset is still mounted. Next, we loosen the two bolts on the left crank arm with a 5mm Allen key, but we do not remove them completely. Now, the crank cap can be loosened and removed by hand using a special tool (TL-FC 16). An additional plastic safety mechanism (retaining plate) in the clamping gap prevents the loosened crank arm from detaching from the axle during a ride. Using a flat screwdriver, we gently tilt the plate upwards and remove the left crank arm. Finally, we thoroughly clean the bottom bracket and apply grease to its inner surface.

To remove the Shimano GRX chainring from the original crank, we unscrew the four integrated chainring bolts and carefully take off the chainring. After any necessary cleaning, we mount it onto the p2m spider using the original bolts. We position the chainring so that the tab faces towards the right crank arm (Photo #1). Finally, the chainring bolts are tightened in the sequence 1-3-2-4-1-3 as firmly as possible (Photo #2).

When placing the p2m spider on the Rotor steel axle (Photo #3), we ensure that the fine groove or the "531" and "24" markings are aligned in the center. This ensures that the crank arm is perfectly straight. Since we are using a round Shimano chainring, the OCP axle lines are otherwise irrelevant for us. Next, we attach the right crank arm onto the axle (Photo #4), tighten it with a 10 mm hex key to 35 Nm (max. 40 Nm), and finally check it for play.

To ensure we don't forget, we first loosen the screw "T" with a 2 mm Allen key and turn the preload ring counterclockwise until it touches the crank arm (Rotor graphic #3).

Based on the bottom bracket (in this case: BSA 68) and the axle (in this case: Rotor Gravel with offset), we identify the necessary spacers and rubber rings. On the drive side (right, "DS"), we need 3.5 mm spacers and the O-ring with 18x2 mm; on the non-drive side (left, "N-DS"), we need 3.5 mm spacers and the O-ring with 24x2 mm (Rotor spacer chart). In practice, however, there's nothing wrong with using more or fewer of these. Ultimately, the chainline must fit, the crank arms must have a symmetrical distance from the chainstays, and the crank should rotate freely but without play.

Next, we attach the spacers on the right side, grease the axle, and insert it through the bottom bracket until the spider is seated. The spacers on the left side follow.

As briefly mentioned above, the set included spacers for BB86 Pressfit (86.5 mm frame width). Depending on the bottom bracket standard used, additional spacers might be required – for our threaded BSA 68 bottom bracket, we needed another spacer with a 2-mm width.

Anyone who doesn’t happen to have a fully stocked workshop in their basement would be wise to get a universal 24-mm spacer kit before installation. Either at a premium price directly from Rotor – or from their trusted online shop.

We grease the protruding axle, including its splines, attach the left crank arm with the opened preload ring onto the axle, and tighten the crank bolt clockwise to 35 Nm (maximum 40 Nm) (Rotor graphic #4). Finally, we proceed with the fine adjustment. For this, we turn the preload ring counterclockwise by hand until there is no more play, and carefully tighten the locking screw with a 2 mm Allen key.

After verifying the smooth operation of the crank once again, we place the chain on the chainring, adjust the rear derailleur if necessary, and mount the pedals – done! Now it’s time to ride and enjoy the new crank with the power2max NG G-X!