Hi m8,
I have a shedload of carbon fibre bits fitted to my Aprilia RSV Mille motorbike.
My Alpinestar GP Tech boots catch the left hand carbon heel guard quite a lot as this is the gear lever side. They end up getting scratched quite a bit.
I've found that T-Cut or similar ( I use AutoGlym Paint Renevator ) works well on scratches in carbon fibre. It lifts them out as long as they are more of the "abrasive" type scratches and not deepish gouges.
After using whatever flavour of T-Cut you have, a couple of applications of wax polish brings it back to looking as good as new.
Certainly works on motorbike carbon and given the fact that carbon fibre is pretty much the same across the board, I would reckon it would work on pushbikes too.