I'm looking for a recommendation for a good bike polish for carbon clear coat frames. Something the fills in minor hair line surface scratches and leaves a nice shine.
Not sure about filling in hairlines, but I have used Pledge and have been very happy with the results!
Bike Lust is very popular, but I've also heard the Pledge recommendation. Again, not sure either will fill scratches, but...
Your best bet is to look beyond the bike forums and head into the world of cars. I know cars and mountain bikes are slower than the world of cycling, but carbon fibre is now accessible to the motorist. Some of them polish and polish and polish and polish. Zaino is well worth a Google...
I was given a can of the FinishLine polish product and think it works really well. Smells pretty good too!
You have two different questions here. The first one, which is what should you use to clean and polish carbon without damaging it, it what most every one here is answering.
The real answer is, you can use just about anything. Pledge, Bike Lust, Turtle Wax, Storck's Carbo'Coat Polish. It doesn't matter, as long as there's a wax base, and no abrasives in it.
To fill the fine cracking in your clear coat caused by UV exposure, you do need to go outside the bike industry. Use detailing clay, like that made by Meguiar's. Their Mild Overspray Detailing Clay works very well to remove race stickers, adhesive residue, tree sap, etc.. which you need to do to prepare the surface before using something like their Swirl Remover 2 to remove the surface scratches and cracking. You can do this with a rag, by hand. You don't need to use a buffer.
Swirl Remover uses a very fine abrasive effect. Used badly, it can damage your paint, but if you read and follow the directions, it's like magic. Just use with care.
DO NOT USE IT ON A MATTE FINISH FRAME.
It will polish up a shine on the matte clear coat, and many UD carbon matte frames don't have much clear coat to begin with. You could expose the carbon.
meguires quick detail car shine is a fine product. Also you could wet clay bar to get rid of the small stuck on grime.