SRAM Quarq Spider and Chainring Compatibility

[scoobydrew]

I purchased a used SRAM Red crankset with Quarq power meter spider attached to replace my regular SRAM Red 22 crankset sans power meter. The Quarq crankset came with 52/36 chainrings and I want to swap my current 50/34 rings over. Both the new and current are 110BCD.

The issue is that the standard crankset uses 4 standard chainring bolts plus a "hidden bolt" that threads onto the backside of the crankarm. The Quarq spider is a standard 5 bolt config, with the 5th bolt hidden behind the crankarm.

It looks like I can actually use my 50/34 chainrings and add in a standard chainring bolt, but I would have to remove the Quarq spider from the crankarm to get a wrench behind that 5th bolt. It's not a big deal to remove it (6 Torx screws), but I'm concerned it will alter the performance of the PM.

Anyone know if removing the Quarq PM spider from the crankarm will impact the power readings? Is there any way I can securely tighten that 5th bolt behind the crankarm without removing the spider?

https://i.imgur.com/jRGcPxIh.jpg

[yinzerniner]

I purchased a used SRAM Red crankset with Quarq power meter spider attached to replace my regular SRAM Red 22 crankset sans power meter. The Quarq crankset came with 52/36 chainrings and I want to swap my current 50/34 rings over. Both the new and current are 110BCD.

The issue is that the standard crankset uses 4 standard chainring bolts plus a "hidden bolt" that threads onto the backside of the crankarm. The Quarq spider is a standard 5 bolt config, with the 5th bolt hidden behind the crankarm.

It looks like I can actually use my 50/34 chainrings and add in a standard chainring bolt, but I would have to remove the Quarq spider from the crankarm to get a wrench behind that 5th bolt. It's not a big deal to remove it (6 Torx screws), but I'm concerned it will alter the performance of the PM.

Anyone know if removing the Quarq PM spider from the crankarm will impact the power readings? Is there any way I can securely tighten that 5th bolt behind the crankarm without removing the spider?

https://i.imgur.com/jRGcPxIh.jpg

Wont effect accuracy but you’ll probably need the knurled nut or another standard bolt combo to reuse the rings. On the hollow red crank with integrated spider the long bolt goes to the back of the arm, but with the spider PM the rings themselves usually have the knurled nut installed.

[floxy1]

It won’t impact accuracy. Just make sure you use a cross pattern when tightening.

[kppolich]

Pull the spider from the crankset and install the chainrings first.
Then install the spider + chainrings with the torx bolts.
You can always run diagnostics on it after you get it installed with Qualivin Legacy and Qualvin BLE