Allez: Powermeter Quarq DFour91 (GXP)

After a lot of “adventures” with Stages I decided to dispose this crap… This stuff was more than unreliable. Battery/Energy consumption horrible, pairing between the powermeter and the computer perceived at 25% of success. And don’t count the weather into… just outrage. As another choice the new pedal-based SRM/LOOK looks quite good but I wanted a traditional crank-based one.

So finally there comes the Quarq DFour91 powermeter – halleluja! This is the only serious opponent against the SRM Origin =D

These tools are needed:

  • Bike Stand
  • 8mm Allen
  • Torx 30
  • BBT-9
  • Torque Wrench
  • Grease

Official Service Manual:

Service/Spare Part:

  • Quarq DFour91, GXP
    • 00.3018.192.172
  • Shimano Dura Ace FC-R9100, 53-Tooth
    • Y-1VP98030
  • Shimano Dura Ace FC-R9100, 39-Tooth
    • Y-1VP39000

Post as guidance? No warranty in ANY case of damage!

As said in the BB-Post the new crank/powermeter will be a GXP version. GXP and Hollowtech II quite similar here is a short lesson about it.


Hollowtech II is a “Shimano standard” with external bearings e.g. BSA and a hollowed 24mm straight axle. GXP is the “SRAM-Standard” with the same specs except the diameter. GXP is 24mm on the drive-side and 22mm on the non-drive-side. Length of both axle-typs are the same, so it is possible to run GXP in Hollowtech II BB’s with adapter cups.

I run a classic setup, which means 53/39 on the crank. The alignment of the chain rings are predefined. The large ring (53) has a chain-catcher which will be hidden by the crank arm. The small ring (39) must be aligned with this catcher, marked by an arrow. The grooves must be faced inside as well.  After that it is possible to torque down the screws in a criss-cross direction with 12-16NM.

Now for the weight-check: 737 grams.

Now everything is ready to be installed but first grease to the contact surfaces: Inner side of the axle as well as the outer side. The left crank-arm is already greased by default, so nothing to do.

Now head for the bottom bracket and insert the axle straight through. On the ceramicspeed bottom bracket there is a cover on the left non-drive-side. Just put it on and screw the arm on the axle. Because this is no pressfit BB30 (PF30) or BSA there is no GXP-washer (wave washer) needed for preloading the bearings.

In the end force is needed. The right torque is 45-55NM in clockwise direction. After that there should be no gap as well as no play against both arms. When everything looks good it is done.

Next will be the group-set, yummy  =)