Here is attached a SRAM XX1/X1 guidelines for the frame builders.
It gives the chainrings diameters, amongst other informations (I just found that document, but can't measure the bike right now)
 

After a deep passage in a river, I thought my rear Hope hub needed to be serviced.

I can confirm it was easy and... fun(yeah, I know, poor of us who enjoy this, especially the hub was still good).
Following this video and, on the cheap, without their tools.

Not sure what bearing they put in the Lefty Project321 front hub, but this one is still spinning like day one.

Once I had a tire that didn't want to seat.

After a similar moment of despair, I did put a strap along the circumference.
To squeeze the tire against the rim. But not too much as it needs to inflate.
Then some soapy water, and moving a bit the tire where the air was going out.

And don't worry about the sealant initially, or you'll get it everywhere.
You can deflate a seated tire, and put the sealant trough the valve.

And one last trick.
If you remove the valve's stem core, it allows a higher airflow into the tire.
Once it pops. Place the core back, and re-inflate.

I don't think it is a frame issue.
The 142x12 DT Swiss axle works fine on my frame.
But the nut can't move, as I did put a headless screw in the small threaded hole on the back of the drop out.

It was proactive. The cable setup is quite poor on the 256 frame.

The hose is easy to change if you have a long cable(with a double length). One hose pushing the other.
I'm not sure changing the bare cable is easy though.

Since you can't inspect, clean or lube the cable easily when routed internally.
I preferred to have the cable rigidly wrapped in the hose end-to-end. And forget about it.

May be it is an overprotection, but so far the shift is still as sharp as day one.
It could be interesting to see after a wet season or two, how both setups compare.

I did it by hand as well.

If you start with a very small diameter, say 2.5mm.
Go through it.
Then take a 3mm, and so on up to 4.5mm (to run a 4mm hose).
Or up to 5mm if you run a 4.5mm hose (jagwire)

It takes about 20' to do it this way.

Great build!

I didn't know Ritchey's pedals.
When my eggbeaters will fall appart(they probably will), I could switch to them.
They are light and come at a reasonable price.
I'm very interested in your feedback.

I removed the whole plastic guide that was sitting at the bottom of the frame.
The pipe that guides the front derailleur came with it.

Now I have a ~6mm hole, just behind the bottom bracket.
It collects all the water/mud it can.

I use a duct tape for now, but need to change it.
And was wondering if you found a more permanent way to plug it.