Have you tried measuring the gap between the dropouts?
Quick look at those two links suggests they should both fit 142mm axle so it is indeed a bit bizarre. I Don’t suppose there is anything forcing the chainstay outward?
You said you fully tightened the axle. If that’s the case and the hub isn’t pressed against the dropout then it could maybe be either
A) there is something blocking the hub from going flush. Like the end cap hitting the drop out or something.
Or B) the axle is too long and the threads are bottoming out before tightening the dropout to the hub. My 2019 specialized (Allez sprint) has a conical spacer between the axle and the frame on the non-drive side. Maybe that’s missing?
I think there might be some kind of spacer missing from the wheel somewhere, the lbs caliper measured the dropouts and they were in fact 142 but the hub was not. It was like 138ish
Going from this on the sigmasports website: “Rear axle: 12mm x 142mm thru-axle compatible (Convertible to Quick Release and 12x135 thru-axle with optional adapters (available separately))”
So it looks as though you have these “optional adaptors” installed? Or maybe just one of them as your measurment of 138 is pretty much slap bang in the middle of the two standards
Seems like they send you the wheel with the wrong adapter installed. Hopefully it came with both, but if not, you will need those adapters for the 142mm width.
I think you all are correct, I bet the wrong adaptor was installed. I bought the wheel as a floor model (never used, but not factory new) so I bet that someone installed one or more of those adapters.
I guess it’s time to try to figure out where I can source those before Saturday, or run 32 slicks on a mountain bike-like course haha. (or buy new tires for my 700c wheels, probably the smartest)
I have these wheels in the Pro version and I remember installing the spacers when I got them. mine were new and I believe the spacers were in the bag with the sealant and tools that Mavic sends.
Related story - I have a set of Enve wheels with DT Swiss hubs on my Boost MTB. Similar spacer except it came pre-installed - however when I pulled the packing protection away from the hub the little spacer went with packing into the trash. Fortunately after a little googling and calls to the dealer I figured out the issue and dug through the trash and found the missing spacer.
Oof, yeah I’m going to get a friend who knows mavic wheels pretty well to look and at least confirm that it’s a spacer issue, but I’m worried I did the same thing and threw something away.
In case anyone is curious, my friend fixed this by id’ing that the wheel was missing a spacer. He had said spacer and gave it to me (on the off chance he’s reading this, huge shout out lol) so I’m good. I still hold that disc wheels can be confusing.