SRAM Red 22 + Quarq Dzero chainring tech question

I’m pretty cheesed off right now.

One of my bikes is getting a spa treatment (full custom respray @ Cleveland Carbon), and while it is gone I wanted to install fresh chainrings on my Red/Dzero crank. It uses that stupid, idiotic hidden ‘knurled nut’ design.

Bought new chain rings. Bought SRAM 5-bolt nut set. Even bought a SRAM 4-bolt set out of curiousity. None of this stuff includes a new knurled nut for the hidden bolt hole. (No, I don’t have the old one from the old chainrings. It was seized, so I had to drill it out, thereby destroying it.)

Would love some guidance here.

  1. Does anyone have the SRAM part number for a knurled nut contraption?
  2. What if I say “F-it” to the knurled nut, and undo the T-25 bolts on my Quarq instead – and just use a normal old chainring bolt/nut in that location, then reinstall the Quarq?

I personally just take off the spider and just use the regular 5 bolt nuts. With that said, if the rings already have the nut pressed into the ring, then I’m not sure how to get that off.

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Normally I’d say you could just turn the spider around, but a Quarq might either not fit due to battery position or it could mess up the power readings (eg it might think your right power stroke is in fact your left).

I found this on r2-bike, looks like it’s the one you need.

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Bingo! I’m ordering those now, because I’ve got a second Dzero I’m working on next month too.

SRAM replied to my support ticket with blistering fast speed – with a few different suggestions. While the agent agreed the ‘right’ solution was to order a correct knurled nut, it was also noted that my “F-it” option of removing the 8x torx screws to remove the power meter entirely from the crank arm was fine too.

So, that’s what I did. I removed the 8x torx (T20) and then just lifted the whole thing off. In the absence of a proper knurled nut for my new chainrings, I simply used a SRAM ‘standard’ chainring nut for all 5 holes to marry the chainrings together. Then, I put the chainrings back onto the PM/crank using the T20 torx @ 4nm torque. Worked perfectly.

Until my while bike gets back from Cleveland Carbon, I won’t know whether I’ve buggered the PM. BUT, I did shove a battery into it and my Garmin easily saw the Ant+ device and zero-reset it without complaints.

:+1: to SRAM (Quarq) tech. Via a simple ‘contact us’ form on their website, I had a reply in about 90 minutes!

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You won’t bugger the PM (it’s supposed to be bolted on like that!). The only issue I can foresee is the bolts loosening off, as you’ve reused the threadlock - SRAM says these bolts are not reusable, but if you clean them and put fresh threadlock on (and frankly even if you don’t) they should be fine. Maybe check the bolts after a few hundred miles just to be on the safe side, but I’ve never heard of anyone having such a problem.

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Hi Edfungus,

I have the same problem and like to use the regular 5 bolt nut, but how can you prevent the bolt from turning while tightening?

Basically you bolt the two chainrings together first, without the spider involved. Then, you attach the spider to the assembled chainrings.

sorry i dont understand this…
Normally with 5 bolts non hidden bolt i put the chainrings on the spider and tighten the bolts.

Now i have a spider with hidden bolt and dont understand how to do it.

Here’s what I did…

With the old chainrings removed from the spider/crank,

  1. Lay the new chainrings together in their correct alignment and flop them onto the spider/crank. Then,
  2. Mark which of the chainring holes are the ‘hidden’ bolt holes,
  3. Take everything apart and stuff the spider/crank in a drawer.
  4. Bolt the two chainrings together at the hidden-bolt hole. At this point, the spider/crank could be in a different room. It is not relevant.
  5. Bolt the chainrings together at all other holes.
  6. Go get the spider/crank from wherever, and bolt the spider onto that chainring assembly you just built.

Hope that makes more sense.