If looking for new, the DZero has Ant+ and Bluetooth so it works with all head units as well as connecting to your phone for settings and updates. I have been very pleased with mine. No idea about older units.

It looks more complicated that it is. With the new Dzero/Dfour stuff:

What's your bottom bracket? GXP or BB30 are easy. Otherwise you need a new BB or an adaptor to fit one or other of those.

What's your BCD - regular (130mm) or compact (110mm)?

Is your spider 4 or 5 bolt? If 4, look at Dfour. If 5, then Dzero; is there a bolt behind the drive side crank arm (hidden bolt) or not (non-drive side).

Then when you get it just mount your chain rings.

For the older stuff (Elsa and Riken), you'll generally be buying the entire crankset, so it's BB, crankarm length, BCD. Elsa measures power on both sides; Riken does one side only. And (IIRC) Riken comes with either aluminium crank arms or carbon crank arms).

Older models than those (eg S90, S975) are basically precursors to the Riken. Avoid anything that is brand specific (Cannondale, Specialized) unless than it is what you're sure you need.

Thanks guys super helpful so far! Does anyone know the timeline each model was released? From what I've gathered, Saturn > Elsa/Riken > Dfour / Dzero?

I recall reading that some models need magnets to be glued to the frame? When did that go away?

With the Elsa/Riken generation; I believe the initially required a magnet on the frame to measure cadence, but then a firmware upgrade enabled accelerometer-based cadence to be used instead. The current DZero/DFour are accelerometer-based cadence only.

Believe it or not, they just simplified the line up :) Assuming you are getting a new DZero meter all of the spiders (the thing that actually measures the power) are the same. It is just a matter if you want aluminum arms, carbon arms, or to supply your own specialized crank arms. Once you have decided that you need to decide whether you want 110 BCD, 130 BCD, or Shimano chanrings...oh yeah do you want hidden bolt or not hidden bolt. If you have a carbon arm do you want it to say Quarq on it or 'Red' (same arms different stickers). Yeah they have a bit of a SKU mess, but they are a great product. A lot of the decisions are pretty inconsequential (at least to me). I didn't care if it was hidden bolt or not (the most recent Red rings can do either) or what the sticker said. But that's just me.

I should add that I'm looking into getting a older generation powermeter.

In that case the DZero is basically the new version of the Riken and the DFour is the new version of the Elsa. You'll be missing out on Bluetooth and all the fancy optimisations (e.g. temperature compensation) that they made in the new models, but otherwise they're very similar.

I'd say anything older than those might be pushing your luck with regards to reliability.

If that is the case I would suggest not going any earlier than the Elsa/Riken generation. It seems like most of the issues got solved w/ that generation.

I have a Rikken. As others said initially it required a magnet but a firmware update eliminated it.

I've had mine for 3 years and it's been bullet proof. My only minor quip is I wish it had BT but that's super minor. So long as your equipment can do ANT then the Rikken or Elsa is a great choice.

Riken does not do one side only. When it was first released, it did total power without isolating L/R individually. A firmware update about 18 months ago was introduced so that the L/R breakdown could be displayed and/or recorded.

Yes, you can choose your own arms. Don't make the mistake I did and buy the DZero spider thinking it'll go on any SRAM crank though. I bought a Force22 crank to put it on and found out the hard way the spider/crankarm interface on the DZero is 8-bolt vs 3-bolt on the Force22 crank. The only crankarms that will work are the Power-Ready cranks(not too many of those out there), and the ones sold directly through SRAM (~$100 AL, ~400 Carbon). On the plus side, if you wanna experiment with crank length it is very simple to swap out the crank arms and relatively inexpensive vs. needing a whole new power meter (Stages, Pioneer, ect.)

Yeah, not knowing the technical reasons behind the change in the spider interface I think they mucked that up. SRAM already has a direct mount interface standard....use that for every freaking crank arm and power meter spider you make. The only reason I could see getting rid of that interface would be to make the splines clockable so you could get rid of the Hidden/Not Hidden SKUs....but they didn't do that so it was a lost opportunity and all they did was create more confusion when they didn't need to.

I did not know that. Perhaps I should update the firmware on my Riken...

@ the OP: there is one further nuance if you are buying just the spider and adding your own crankarms. The newer Quarqs use 8 bolts to secure the spider to the drive side crankarm; the older ones use 3 bolts. It's something I only realised when looking at whether I could upgrade my (3 bolt) Riken and Elsa to the DZero (8 bolt) simply by swapping the spiders.

ETA: beaten to it on the 3 vs 8 bolt thing.

In other news, I now have some 165mm GXP Force22 crankarms laying around if anyone needs them...

Here is a question that has always plagued me:

Why would ANYONE ever choose the hidden bolt design?

Thanks everyone, I'm currently looking for a complete crankset. I have the stock FSA Gossamer crank right now, so I guess the Elsa or Riken would be an upgrade.

I've heard it provides better ZO stability.

From a normal crank design perspective it actually makes sense to integrate one of the 5 legs into the arm itself that already has to be there and can already support the forces. It could theoretically weigh less not having to have that extra leg.

From a power meter standpoint (at least one where the spider is measuring the forces) it doesn't make a lot of sense except for compatibility with existing rings that have the chain retention pin in the hidden bolt position. This is of course mitigated by the SRAM rings that have 2 pins, one for each mounting position, that you just snap one off.

I kinda assumed that is why they changed it...but I've still have issues w/ their solution and implementation. It should have been clockable for hidden/non-hidden patterns to eliminate a bunch of SKUs. They should have rolled it out across the entire road line up in one fell swoop so everything was interchangable.

I know I'm monday morning quarterbacking the heck out of this....and the second part isn't exactly easy when you are talking about a company as big as SRAM...but they have made a little bit of a mess for themselves for compatibility.

For the Pre-DZero models a Quarq timeline or model comparison is complicated. I think things went kind of unlabeled after the original Saturn when this then became the CinQo. Or at least that is what I think my SRAM S975 based Quarq was called. They then released various versions of the Elsa R and the Riken. Basically the Riken was a response to providing a lower price point. It may have been a little heavier and shown with looser specs, but was essentially the same PM as the Elsa R. This was evidenced later when the V23 firmware eliminated the need for magnets on both models and removed the powerbalance lockout from the Riken.

Where things will get more confusing with the Riken/Elsa R is which versions have the "10k multipoint temperature compensation" activated. Quarqs were notorious for zero offset drift due to temperature swings. I think this capability was essentially, Quarq testing each PM produced, across a temperature range and then inputting the drift values into a firmware table for that particular model. This too was a firmware V23 change. Units produced after this release included the temp compensation info and owners could send their older Riken/Elsa R's back for testing if they wanted this feature added.

See revision history here for unit series: https://www.quarq.com/...sx2jf84pcf2hgwiivns3

See firmware history here: https://www.quarq.com/...sx2jf84pcf2hgwiivns3

Between the Riken/Elsa R models and the new DZero units there were a couple of other unique releases. The Elsa RS Shimano 4 bolt chainring compatible model and the XX1 single speed mtb model. I believe both of these models came with what became the new Quarq 8-bolt spider pattern.

This reference is kind of difficult to find on the Quarq site. The 8-bolt list on this page outlines which models originally came as 3-bolt spider pattern and then were changed to 8-bolt: https://www.quarq.com/...sx2jf84pcf2hgwiivns3 Not necessarily a problem for you buying an older model, but if you are trying to mix and match spiders and different crankarm lengths.

Considering that they actively chose to redesign the spider interface then you'd assume there were some practical benefits with regards to power measurement. i.e. they were using the 3-bolt design with the carbon Riken R and then changed it to the 8-bolt design with the Riken AL and throughout the new DZero line.

One of the stated improvements of the DZero was improved accuracy of inner- vs outer-ring measurements, so perhaps the 8-bolt design facilitated this?

I loved my Elsa. I just got rid of it about 4 months ago because I changed crank lengths. I never had a single issue with it.
I picked up the Dzero

I'm in that boat now, riding a circa 2015 Quarq Elsa with 172.5mm crank-arms and looking to move to 165mm. Quarq will make the swap, but (1) having the LBS pull the crankset, (2) waiting for the replacement and (3) going back to the LBS for the reinstall is such a hassle that I'm considering whether I should just buy a new power meter.

Was that your situation as well? Assuming you went shorter, how are the shorter cranks treating you? How does your experience with the Dzero compare with the Elsa?

Scott

I have an s975 and am doing the same thing, except I'm sending it directly to quarq. No difficulty except waiting for the swap. Definitely a lot less expensive than a new powermeter