SRAM XPLR or Mullet still?

So I’m upgrading the Gravel frame and it’s wireless (Di2 with a new hole) only. The current bike has mechanical GRX on it so will have to find a new home.

Question is: Do I buy SRAM’s shiny new XPLR, give myself more gears with a Mullet or hold out and hope that there is a semi-wireless GRX groupset in the pipeline…

I’ve definitely felt the pain of not having enough gears on a long climb with a fully loaded bike so the mullet has it’s attractions. I’d also like to keep it fairly simply in swapping wheelsets between bikes and therefore Shimano would be the preference - a semi-wireless GRX would solve my issues there.

Thoughts welcome!

Good question! I struggled with a similar conundrum for the last few months while looking for a new gravel rig.
In the end, I went for the Cervelo Aspero-5 with Force XPLR, and am SO glad I did! It is incredible…coming from a 2x gravel setup (50/34 crank with 11/36 cassette) I wanted a groupo that would allow me to maintain speed on flats while giving enough gears to comfortably spin uphill. The XPLR absolutely fits the bill there…it’s a perfect range for riding to, on and from my local trails. With an FTP of around 335, I can still maintain speed on flats under power, but have more than enough range to climb the steeps of West Coast BC hills.
I am used to riding GRX and Ultegra Di2, but they couldn’t (yet) compete with the gravel-specific range of the XPLR.
Hope you land on something that works for you!

I’d stay with the mullet, and do a smaller chainring (30/32/34) with a 10-52 setup, and then buy the XPLR casset 10-44 and a bigger chainring (40/42/44 so you don’t have to use two different chains. One of my buddies is doing this exact thing with his gravel bike and really like it since switching out the chainring and cassette doesn’t take too long especially if you know you got some climb heavy days ahead of you.

I really like the mullet setup. I suppose it’s a bit more weight, but we have some big gravel climbs and I use the 50t. I run a 48 front ring, and treat the bike as an all-road bike. I almost never miss the double with the wide spread.

Given you can get a 40T cassette with a normal di2 RX cassette never mind a bigger one with one of those mech hanger extenders, the options are huge for most things. I’ve got an XT 40T cassette I use on my gravel bike when I have luggage and with that and a compact I’m pretty happy.

The Sep 2nd CT Podcast episode was a long interview with a couple guys from Shimano, talking all things Di-2 semi-wireless. Time will tell, but I think Sram AXS still has the advantage, at least in the 1x gravel/MTB world (is Di2 MTB still in production?)

They wouldn’t say either way when asked about GRX Di2. I would imagine eventually that it could come out but that could be a year.

Sram XPLR is also not-quite-available… and I just read some fine print on it:

  1. It is 1x-specific; so no 2x option
  2. The XPLR rear derailleurs require the “Flattop” chain. For Sram, the 12 speed stuff has chains that have to match the rear derailleur; flattop for Red/Force/Rival, Eagle chains for Eagle AXS rear der. And XPLR is 44t max rear, where Eagle can go to 52. But the cassettes can be interchanged.

My argument for Sram MTB/EAGLE AXS:

  1. It’s available NOW. Not sure on your build timeline but Eagle AXS is now at three price points, GX/XX1/X01. Build kits are out there (if in stock) now.

0.5 If you have Sram Eagle MTB drivetrains already (AXS or acoustic) then chains are common.

  1. Separate batteries for front and rear, AND a spare battery can go in your seatbag. Range between charges is like a Di2 seat tube, but swapping out for a spare, or front/rear swap is no problem. On a ride last week, another ride had his battery die, I loaned him my spare and he could finish the ride (still looking for my beer…)

  2. Shifter/controller battery is CR2032. The universal fitness electronics battery. They last for years and years. The new Di2 uses something else (1032? something-32) which I have none of. I’m sure they’re widely available. But I couldn’t swap my HRM battery in a pinch.

  3. AXS is fully wireless. Maybe this is from bad experience but a bike that gets dirty and wet, then has wiring running through places like a bottom bracket, what could go wrong? Currently trying to troubleshooting what appears to be a wiring problem on an older di-2 road bike.

  4. AXS battery charging. The base is proprietary, but takes a micro-usb power source. The base weighs 38 g (just threw mine on a food scale) so you could fairly easily pack one and using any USB power source ride forever. Shimano Di2 uses a proprietary charger as well, but (at least for my gen 2 version) while USB powered, it needs a “high current” USB source to properly charge, and is a much larger “brick” on a wire.

  5. Mullet capability: I run 44t front, 10-50 rear. I’m about 3.5 W/kg these days, and for an east coast (short but punchy hills) that does the job. I was just in San Diego and rode parts of BWR, and some of the San Diego hills. I would probably go down to 42 or 40 on the front since some of those hills were pretty painful. Shimano can get you more range with a 2x setup, which is an option for AXS as well. You can start 1x, then if needed add on the front derailleur if you wanted. Now Sram doesn’t do 2x as well as Shimano (I heard it’s a lot of patents that Shimano has that forces Sram to work around) and your frame/chainline may also have issues.

  6. Sram MTB lineage: Not sure what your terrain is like, but after riding in San Diego on some sketchy (for a gravel bike) trails, I’ve come to appreciate the MTB heritage of AXS and Sram. The Eagle AXS rear derailleur is a work of art.

On swapping wheels between bikes; not sure what issues there are between Sram and Shimano unless you want to swap cassettes also. Both Di2-Wired-less and AXS are 12 speed, and while the hubs are different, I think as long as the speeds match, I think you can swap things around. Once you get into the hubs though things are different. I heard that to upgrade Shimano from 11 to 12 speed, that it’s just a matter of changing the cassette.

There are smaller jumps between speeds on Eagle. I’ve had to adjust my cadence since going 1x on the road. Depends on how flexible you are with that; that could be a consideration for XPLR. But I think you could start with an Eagle 10-50 and then swap to a 10-44 if you wanted those tighter jumps. (Got me thinking about this now)

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This was one (of many) of the deciding factors for me. Especially given the potential for spinning out with a 1x, I really wanted the tighter jumps that comes with XPLR. When I’m pushing on my gravel bike, I don’t want to shift and lose cadence.

I’d stick with Mullet, for three reasons:
-Adaptability / component choice. Since it’s based on the Eagle 12s ecosystem there’s way more options to source parts that will work nicely. Also the chain, chainrings and RD will work with a lot more non-SRAM manufacturers. If you go with XPLR you’re stuck with their chain, cassette and RD.
-Availability - XPLR won’t conceivably be available anytime soon.
-Overload clutch, which moves the RD out of the way during an impact.

The post above where they have multiple front chainrings but the single cassette and chain seems like the best option - kjnow your cadence, plan a route and then stick on the chainring that’ll give you the most comfortable gearing.

Though if GRX Di2 goes wire(d)less then all bets are off. The hood shape is incredible

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According to Ratio Technologies, the cog/sprocket spacing between MTB Eagle and road AXS (including XPLR) is slightly different.