Earlier quoted context omitted.
20k rpm is relatively clunky F1 combustion engine territory. I find it hard to believe spinning an electric motor and a relatively light and small disc that fast is much of a challenge to keep together, especially in such a coddled environment. Even back in the early 90s my RC10 had a 38k rpm "modified" motor; the Motown Missile. That thing lived through hell...
Tesla Model S Plaid electric motor is said to reach 20k RPM but needs to be carbon-sleeved: https://www.reddit.com/r/teslamotors/comments/o4k0xa/up_to_2...
CBR250rr to 20, and those were actually street legal, and there are still a lot of them on the roads.