the differences are in crank arm construction and material. the quarq arms are the equivalent of the force crank arms. the red arms are hollow exogram design and a bit lighter. that and about $180 dollars.

The Quarq DUB crank arms are still really light, if you pair them with even a Dzero spider you end up with a 470g power meter crankset which is crazy. I'm not sure if there's actually a weight difference in the real world between the two?

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AeroCoach UK
http://www.aero-coach.co.uk

Xavier, that's exactly what I am planning to do. I've ordered your ARC chainring to combine with the SRAM AXS Power Meter Spider, but I wasn't really sure what would be the best crank arm assembly, as I haven't been able to find the difference between the two.

Ah great! That's quite the coincidence, thanks for choosing our kit. I would go for the cheaper ones - I'm actually in the process of doing a weightweenie build at the moment and have got a pair of them with a Dzero spider which is how I've got their exact weight.

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AeroCoach UK
http://www.aero-coach.co.uk

I have some older ”pre AXS” etap red crank arms that are 8 bolt pattern. Do you know if they should work with the AXS powermeter spider or AXS power direct mount chainrings? Sram said the chain line would be off, but I am not sure they knew exactly what I was asking. I don't want to by new crank arms if they are compatible.

Will be checking out your options on chain rings as soon as I put base the new bike.

On a side note, have you been able to do any testing with your wheels on a Cervelo PX? Any results you can share?

I think that yes, the chain line would be off as the new spiders are designed for DUB cranks only.

We do testing on our wheels in Cervelo frames as part of our protocol as they tend to reflect overall performance in other brands very well - we don't have published wheel data on PX series bikes (although we have had them in sessions under clients before), but I wouldn't expect anything different from what we've found in our published data.

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AeroCoach UK
http://www.aero-coach.co.uk

Quarq told me the quarq arms and red arms are the same, but branded differently (and hence the price difference). Both use the hollow exogram design. The force crank arms are a bit heavier and use a different design.