Quarq DFour91 GXP to DUB Conversion?

Equipment
1

Hi,

I have a Quarq DFour91 GXP with 175mm crank arms. Knees are giving me trouble so was thinking of switching to 170mm or 165mm…

But since GXP is being phased out, there are like none to be seen, second hand or new.

But… I found new crank arms with the DUB spider, and the crank arms have the 8 bolt attachment that seems to be same for the GXP crank arms…

  1. Could I replace the crank arms to DUB, with the same spider that I have right now? Seems to me that the spider is the same, but the crank arms dictate the spindle standard?

  2. From what I understand, there is a spindle length difference as well, so there might have to be some kind of spacer on the drive side?

  3. It will be installed to a 2020 S-Works Venge. Right now I am using the original CeramicSpeed with Wheels MFG adapter to GXP. Would I need to replace the whole BB to work with DUB?

Thanks!

Here is the 8-bolt standard that seems to be the same regardless of spindle, top one being the spider for GXP, and bottom one being the spider that is the one that can be bought now - DUB:

QUARQ-DFour91-Power-Meter-Spider-black-110-mm-58733-334983-1589953634
QUARQ-DFour91-Power-Meter-Spider-black-110-mm-58733-334983-15899536341280×960 66.7 KB
product.php
product.php760×570 25.5 KB

And here is the crank arm “kit”:

quarq-crank-arms-for-dzero-dfour-dub-black-4
quarq-crank-arms-for-dzero-dfour-dub-black-4613×613 39.5 KB
quarq-crank-arms-for-dzero-dfour-dub-black-2
quarq-crank-arms-for-dzero-dfour-dub-black-2613×613 25.8 KB

2

Here goes:

  1. Yes, you can re-use the power meter portion with the new crank-arms
  2. I would reach out to Quarq and ask them
  3. I think you will need to buy a new bottom bracket. I don’t see any DUB adapters on the Wheels MFG site. But I would reach out to them for the definitive answer.

Cheers

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3

I had the same idea earlier this year but from a standard 130 BCD 5 arm Quarq Dzero with GXP spindle rather than the dfour. I got in touch with Quarq/SRAM and they told me the new DUB crank arms were not compatible with the spider I had and replacing just the cranks for a shorter length on my Dzero was almost as much as buying the new AXS/DUB spider and cranks separately. (Might be different for the dfour so I’d reach out to them before buying anything).

I ended up selling my old PM and replacing. I was using an outboard Wheels MFG on a Specialized Allez Sprint and had to change the whole BB. I’ve been using the SRAM DUB BB for BB30 and so far it’s held up well. Better than my previous experiences with SRAM gxp BB’s in typical British weather.

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4

@jtuk @AlphaDogCycling

Thanks for the answers, I was just about to order and I thought that it might be good to ask SRAM themselves first. Here was their answer:

“Unfortunately the new DUB cranksets use a different mounting plane that makes them incompatible with your DFour91 crankset.”

Good to know for anyone that is thinking of trying the same! :slight_smile:

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