Power data on a light carbon road crank, in one package. This pairs Praxis's Doon carbon arms with XCADEY's XPOWER-S Gen2 spider power meter, which measures total power at the spider to ±1% and charges by magnetic USB rather than taking coin cells.

Highlights

Praxis Doon carbon arms: 342 g for a 172.5 mm arm set
XCADEY XPOWER-S Gen2 spider for SRAM 3-bolt direct-mount cranks, ±1% accuracy
Power, cadence, left/right balance and pedalling smoothness over ANT+ and Bluetooth
Rechargeable lithium battery: up to 350 hours per charge (XCADEY figure), about 3 hours to charge
110 BCD Praxis Buzz or Aero road rings, 10/11/12-speed
M30-THRU 30/30 mm spindle, 147 mm Q-factor

The power meter

The XCADEY XPOWER-S Gen2 SRAM 3-Bolt 110BCD is a spider-based meter for 3-bolt direct-mount road cranks. XCADEY lists the Praxis Doon as compatible, and Praxis lists XCADEY 3-bolt meters as a Doon power option. It is CNC-machined from 7075 aluminium, weighs 110 ±10 g without rings and uses eight strain gauges with temperature compensation. It is rated IP67 and reads 0–2500 W and 30–220 rpm.

It talks ANT+ and Bluetooth, so it pairs with bike computers and apps that read ANT+ or Bluetooth power, and XCADEY has its own iOS and Android app. The built-in rechargeable lithium battery (150 mAh) charges through a magnetic USB port.

The crank

The Doon is Praxis's pro-level carbon road crank, made with its in-house C.R.A.F.T. carbon process, on an M30-THRU alloy spindle that is 30 mm at both bearings with a tunable preload ring. It is a road crank: Praxis designed it for road 2x groups, and it is not compatible with Shimano GRX front derailleurs.

Options

Option	Rings	Speeds
52/36T Buzz	Praxis Buzz 110 BCD road rings, their lightest set (158 g for 52/36)	10/11/12-speed
52/36T Aero	Praxis Aero 110 BCD rings, solid aero/TT style (182 g for 52/36)	10/11/12-speed
50/34T Buzz	Praxis Buzz 110 BCD road rings	10/11/12-speed
Crank length	165mm, 170mm, 172.5mm or 175mm, with every ring option	—

Compatibility & fit

Bottom bracket: needs a 30/30 mm bottom bracket, sold separately. Praxis's M30-THRU BB comes in BSA, BB86, T47 internal bearing, T47 external bearing, BB30, PF30, 386EVO and BBright versions, and Praxis says other brands' 30 mm BBs also fit the Doon's spindle.

Drivetrain: 2x road groups from Shimano (Di2 and mechanical), SRAM (eTap and mechanical) and Campagnolo (EPS and mechanical), 10/11/12-speed. Not for Shimano GRX front derailleurs.

Head units: any computer or app that reads ANT+ or Bluetooth power.

The Tune Cycles workshop can fit the bottom bracket and crankset for you as a separate workshop service. Threaded shells need the right BB tool and press-fit shells need a proper bearing press, so it pays to have the shell checked and the bottom bracket fitted correctly first. The main crank bolt is torqued to 48–52 Nm with a torque wrench. Pairing the power meter with your head unit and calibrating it are also separate workshop services, and we can do both when we fit the crank.

Praxis warrants the Doon crank against defects in materials and workmanship for 2 years from the original purchase date, for the original owner with proof of purchase; normal wear and tear and damage from a crash, abuse, modification or incorrect installation are not covered. XCADEY covers its power meter spiders for 2 years from the purchase date.

This is in addition to your rights under the Australian Consumer Law. Keep your proof of purchase.

For warranty support, return the product to Tune Cycles and we'll manage the claim with Praxis's Australian distributor.

XCADEY XPOWER-S Gen2 spider power meter, ±1% accuracy
ANT+ and Bluetooth; power, cadence, L/R balance, pedalling smoothness
Rechargeable lithium battery with magnetic USB charging, IP67
Praxis Doon C.R.A.F.T. carbon arms, 342 g arm set (172.5 mm)
M30-THRU 30/30 mm alloy spindle with preload ring
110 BCD Praxis Buzz or Aero road rings

Crank	Praxis Doon, carbon arms
Spindle	M30-THRU alloy, 30 mm drive / 30 mm non-drive bearing
Bottom bracket	M30-THRU (30/30 mm), sold separately
Q-factor	147 mm
Arm set weight	342 g (172.5 mm, Praxis figure)
Power meter	XCADEY XPOWER-S Gen2 SRAM 3-Bolt 110BCD spider
Measurement	Total power at the spider
Accuracy	±1.0%
Data	Power, cadence, left/right balance, pedalling smoothness
Connectivity	ANT+ and Bluetooth 4.0
Battery	Rechargeable lithium, 150 mAh; up to 350 h; magnetic USB charging, about 3 h
Power / cadence range	0–2500 W / 30–220 rpm
Water resistance	IP67
Operating temperature	−10 to 50 °C
Spider	CNC-machined 7075 aluminium, 110 BCD, 110 ±10 g without rings
Chainrings	Praxis 110 BCD road rings (Buzz or Aero), 10/11/12-speed
Options	Crank length: 165mm, 170mm, 172.5mm, 175mm. Chainring: 52/36T Buzz, 52/36T Aero, 50/34T Buzz