Carbon fiber is a material that is relatively new in the biking world but has been around since the 50s when it was first developed, in a weaker, low carbon version, by a guy named Roger Bacon in Cleveland, Ohio. It was further developed in Japan and Great Britain in the 60s, with Rolls-Royce taking the baton and leading with innovations in the development of jet engine parts.
I’ll probably repeat it a bah-jillion times but it is worth repeating: if you are bleeding hydraulic brakes, mineral oil and DOT fluid ARE NOT INTERCHANGABLE! It’s kind of like when they tell you not to put diesel in a regular gas engine. And in this case, super faulty braking can be the result. Thing is that DOT fluid is classified by number, from 1 to 5. The higher the number, the more head the fluid can resist therefore helping the braking accuracy when you are super grinding on the brakes, especially you downhill folk.
You look at the damn thing and think “Who is the insane bastard who decided this was safe and necessary for biking?” But lots of people use them and the argument is that it’s more of a natural movement (albeit on a flat surface) in comparison to using a trainer. With a trainer, you mount your rear tire on the roller but it does elevate you slightly so if you don’t have a riser, the feeling of you going slightly downwards is a little disconcerting.