Carrier is marking frame
 

I noticed the carrier I am using seems to be rubbing the cf frame and leaving rubber on the bottom of the top tube.
Is this normal?
What cleans it easiest?

What rack are you using? That is generally not common. I would start with isopropyl alcohol.

1- eliminate swaying and shifting.
2- buy a tray rack that holds the bike by the tires.
3- place towels between the frame and the carrier contact points if you cant otherwise stop the swaying.

It’s an Allen that straps to the spare tire on my Jeep Wrangler.
I noticed the rubber cushions are rounded but the top tube on my Specialized Roubaix is sort of boxier shaped.
I think is wiggles back and forth a little on the carrier.

The carrier is strapped on my jeep's spare tire.
I could get a carrier that uses the receiver hitch but having to remove it to open the tailgate would be annoying.

I bought the carrier used. Is it possible the rubber is just degrading?

I've used those Jeep spare tire carriers before. They're fine. Just make sure the the bike doesn't move. Maybe try pool noodles at contact points

That is a good idea. If it will fit with the bike on it.
If not I will put a rag on them.

Old gym socks. Or you can buy a bag of rags from somewhere like Lowe’s.

You don't have to remove it...Most of them tilt downward for that purpose.

Tailgates on Wranglers swing open. Not sure a tilting rack will provide enough clearance for a swinging tailgate.

Yup, and racks mounted to the spare tire swing open with the tailgate.

The only thing to watch out for is to not exceed the bearing capacity of the tailgate hinges.

You could also use vinyl wrap on those parts of the bike that touch the rack, as a replaceable protective layer.

Cleaning: First option, just try rubbing it off with your thumb. Second option, Dawn dish soap and water.

I would trash it and get a better rack. I have yet to see an Allen rack I would trust with any bikes and a used one that has play between carrier and bike I trust even less. I know Yakima made a spare tire carrier which was decent if a hitch is not an option and those are good quality racks.

I look on marketplace for a Yakima that bolts to the spare tire. I guess it’s time to get serious.

I am assuming marketplace is a used spot and since racks are safety items used is a poor way to go. You don't know what condition that rack is in or what someone has done to it, so I would skip used and go brand new from a place you can trust that is an authorized dealer for Yakima or Thule or other quality rack brands.

I would never use a rack like that, and never one the straps to the spare wheel. They are crap and not very secure. Get a tray rack. You will have to get an extender to clear the spare, but you can get one that also drops the height of the rack by a few inches, which allows you to swing open the gate with the rack on it. In my experience, the only way to carry a CF bike is by the wheels, not the frame.

Hi-Lo hitch extender: Kuat Hi-Lo Hitch Extension | REI Co-op

I've used the Kuat Sherpa with the Hi-lo extender on both a Bronco and Wrangler over the last 5 years, and was able to open the gate with both vehicles. The rack also only touches at the wheels/tires.

Buy right the first time, and you only have to buy once. Much cheaper in the long run.

I will be looking at a tray rack.
I need to do something soon. When I loaded up to go ride one of the nylon straps that hold the bike on the carrier broke. That tells me the other straps are also weathered and can’t be trusted.

I drove my Jeep thousands of miles with a spare tire mounted bike rack. And the OP did not mention carbon fiber.

Search "Kuat" on FB. Or buy new and get a warranty.

Post #1 - "cf frame."

A better quality carrier would be better than this Allen. It was cheap.
It was also meant to be strapped onto a stock size tire. I have 33” BFGs.
I have been looking for a Yakima that bolts to the spare tire.

my bad