Tried this on my VeloBuild aero gravel and it works well, there is some very minor play between the interface on the final part between the grinding disc and the arm. Apart from that so far so good.
Faced mounts so far with a simple file and trying the caliper on which quite a bit of time because you are constantly taking off the caliper.

My procedure with file facing is: have the wheel on with the disc, mount caliper WITHOUT the brake pads and tighten either bolt and see what happens between caliper and the disc and then file to opposite direction.

With this it just seems simpler.

Facing with a file I get to "good enough" and with this while not perfection I get most the way there.

Bonus points that my VeloBuild front thru axle does not fit to the front axle fitting lol, tried TanTan thru axle and it works.

About to pull the trigger one of these X68 frames and had some questions..

-Is it worth shopping around on AliExpress for an upgraded handle bar, such as ones that are compatible with SL8's? Just how flexy are these stock bars? Has anyone tried a different integrated cockpit with success? Worth it to shop outside of AliExpress?

-Recommend upgrading steerer plug or are folks having good luck with the one supplied?

-Out of precaution, any tools or methods to help clear excess carbon out of the seat tube for Di2 battery?

-Should I just book a time at my LBS to have the brake mounts faced or can it reasonably be done yourself with a file and some elbow grease?

Feel free to recommend any other parts or supplies for the build.

How optimistic is it to expect it's arrival to the states by end of July if ordered tomorrow? (6/12)

At first I thought that the handlebar was a real noodly one, perhaps because just before I built and rode a Velobuild Aero Gravel that literally has no flex anywhere. Now after close to 5k km I find that it just perfection.

I had something on the seat tube but after some juggling Di2 battery went in. Did not come out though when I switched to a 0 offset post. So far no noise from it so I quess for now it can just chill there.

Brake mount filing was a bit of a pain in the ass for the front mount, can still hear a rub on hardset sprints. Rear only required minor filing.

Parts that I replaced: headset bearings, seatpost, derailleur hanger
Parts that I would also have replaced with what I know now: headset spacers

@ everyone with a VeloBuild Aero Gravel frame:
What is real world maximum tire width WAM?
Thankful for every answer!

Mounted and inflated Racing Ralph measures almost exactly 51mm. I can move a 3mm measured allen key between the tire and chainstay but not without resistance.
I would say 52mm is absolute maximum.

Of course tire shape does play some part in it too.

Front brake rub was easily fixed by minor filing, fast job compared to the horror of my Velobuild Aero Gravel.

Another problem is plasticy squeking from the headset area. At first I was 100% certain that it was from cleats. Noticed that the bottom most spacer is slightly touching the frame at both front and back. Will try if minor sanding will fix it. On my fact finding mission this same problem seems to affect genuine frames too.

Dude thanks for this feedback, is it possible for you to post some images of your setup and a comparison of the seatposts? I have bought my SL8 from yohobikes(the seller is a douchebag) and I have been baited and switched apparently and was told to just ignore some minor flaws (fact carbon 12r in the wrong place in the downtube deliberately ommitted on the QC pics I asked, probably a rejected frame from a previous buyer, totally my fault as I was rushing to build one due to an upcoming local race last year sheesh!)

Now I am debating myself if I will be getting a genuine roval rapide handlebar vs an EXS Aerover and a zero offset seatpost. Did saw some
Offering in aliexpress. I noticed the genuine handlebar and seatpost definitely has a lighter gray tone compared to the ones that come with the yohobike special plus there was no computer mount included in the package for mine hence I went with a tasty looking magcad wahoo bolt v2 that some of the other guys got. Will post my setup soon.

I have not used the setback seatpost that came with it. I slightly modified the Ali post by wrapping two layers of car rock strike protective film on the sides and backside of the post but kept the front part where the clamp touches clean. Titment is better, though it did not slip even without wrapping but I quess it wont do any harm. Still dont like the 1 bolt saddle securing solution, it slipped a bit today when hitting a big pothole.

Frame is 58, group is full ultegra di2, Assioma duo, Elite Rocko cages, Framesandgear wahoo mount. According to my luggage scale it is 7,25kg ready to ride.

Finally got around building mine. Routing left side on the cockpit was absolute nightmare, broke my routing tool too. Ended up filing the hole a bit. Lots of snagging on to something and the shifter end hole is just wrong, it looks like it is drilled directly to behind instead of an angle.

Routing mechanical rim brakes on my Lexon cockpit was a breeze compared to this.

Pretty damn annoyed with the headset and cockpit. Cockpit required good bit of filing to get it flat, bottom was horribly uneven.

Second problem is with the metal U-ring being too thin, dust cap sits against the frame. It is fine with some shims but it does not look like an ideal solution because of the internal cable routing. I am kinda afraid that over time edge of the very thin shim will cut into the brake hoses.

Any ideas? I thought about cutting the shim just under size of the U shaped ring and gluing it to the dust cover.

Update on this.
Emailed Chris about headset and he offered to make a taller compression ring as shimming was not really ideal. Instead of a new compression ring I did buy a new upper bearing that is 1mm taller so 40x52x8 instead of the original 40x52x7. I think space between frame and dust cap is great right now.

Size 58 matte black weights: frame 869g with hanger and front derailleur plate, fork 392g has no QR stickers or stickers of any kind, 110/380 cockpit 338g, seatpost with mounting hardware 186g.

Looks and feels fine apart from rear brake mounts that do not appear to be faced at all and BB threads that look rather rough but to finger feel ok. Computer mount is outright ugly.

Going to take a while until I get all the parts for the build.
Planning on running 32mm S TR on 26i rims, anyone tried 32mm? Most posts I have read have been with 30mm.