rear rack no bottom eyelets
 

Any advice for mounting this rear rack? I there are screws up top, but nothing to fasten to below.
https://cimg7.ibsrv.net/gimg/bikefor...b625eae678.jpg

What bike is that?

Tubus makes an adaptor for QR hubs. You could take that idea and fabricate something. Alternatively, change the upper mount and use P-clamps on the seat stays.

It is a State 4130 Single Speed

I used one of these.
Amazon.com : Topeak MTX BeamRack Bike Mounted Rack : Sports & Outdoors
I used one.
https://cimg4.ibsrv.net/gimg/bikefor...cf188a78cb.jpg
https://cimg0.ibsrv.net/gimg/bikefor...a9873b83f6.jpg

Forgive me for being a newb, but it looks like the QR adapter goes through the middle of the hub. Is that true, and if so, is that hole load-bearing?

P Clamps are cheap, they clamp to the seat stays (or any stays.

P-Clamps for Fender Attachment – Velo Orange (velo-orange.com)

The QR system is not load bearing in the shear direction. It's a tension device only. It clamps a hollow, shorter axle to the frame dropouts. The ends of the axle do not extend past the outside of the frame. So you can't use it for a solid axle, but one could fabricate similar adapters. As mentioned above, P-clamps are much easier if you can make the upper hardware work. Often that needs to be modified anyway.

https://www.tubus.com/fileadmin/user...ner_MA_1.0.pdf Here, it looks like the QR system's rod goes through the hub and supports the weight of the rack.

Sorry, I thought you meant the weight of the bike and rider on the hub. Yes, the QR supports the rack weight, but it's a moot point since you don't have QR.

also know as "Adel clamps" or MS21919 clamps; make certain that you get the kind with the corrosion-resistant steel bands, they are stronger than aluminum.

However, I do have a similar hole in my hub. I am wondering if a threaded rod and a nut/washer could work

P-clamps are probably the easiest way to deal with this. Make sure you get steel ones; plastic p-clamps are only strong enough for mudguards.

Alternatively, Blackburn used to make "custom eyelets" that fit in the window of the dropout. You can still find them on e.g. eBay.

I'm not fond of mounting racks on the hub axle; it makes wheel removal awkward.

also know as "Adel clamps" or MS21919 clamps; make certain that you get the kind with the corrosion-resistant steel bands, they are stronger than aluminum.

I've used the Adel clamps on a previous bike with good success. The fitting you link above would work as well. The other option is get a flat piece of stainless, drill a hole for the axle on one end and thread in an eyelet on the other end for the rack.

If that bike is unpainted stainless it would be pretty inexpensive to get someone to weld on an tab for a rack mount.

I had a set of these once worked great. I recently made similar using m5/6 bolts, washer and plumbing rubber cones..... it OP is creative and can do a few trips to ACE it is really not that difficult to do....just fiddley

+1 on P clamps. Give it a try. Inexpensive, widely available locally (usually), and quick to try. More than likely will work well.

P clamps from the hardware store, they should work with a rack. Wish someone made some bicycle specific ones that looked better. They'd probably sell a lot of them.

https://i.postimg.cc/Y23zs1zF/mnnnn.jpg

Here's what the Blackburn rack adapters look like in real life.

https://cimg9.ibsrv.net/gimg/bikefor...8383c9e556.jpg
https://cimg0.ibsrv.net/gimg/bikefor...5f7eb6c261.jpg

Cheers