>>2043918
https://www.porkchopbmx.com/dia-compe-flexie-flexible-bicycle-v-brake-noodle-b.html

>>2044114
Look up Rob English's bikes. But making something more aero isn't as simply as making it narrow, and CF has big advantages when you're making non-round shapes.

>>2044286
Both a fad and better in some ways. Depends on your fit whether you'd benefit from shorter cranks and opening your hip angle.

>>2044606
I'd say no unless you're cleaning lots of small parts regularly. Otherwise ordinary degreaser, soap, and elbow grease are less faff than getting things into an ultrasonic cleaner (and the inexpensive ones are tiny)

>>2044654
You're probably hearing star ratchet freehubs. They're noisy, but give very quick engagement while still being durable.