There seem to be a lot of ebike-related questions that involve information about not only bicycles, but also electrical engineering, and even mechanical engineering. I'm not much on social marketing though, & have never considered proposing that a new stack be launched... aaaand: The area51 site for proposing new stack sites, says "If you do not yet have a community organized, ready and eager to build your site, please do not submit this proposal."
So, I don't know, how many stack users might follow a proposal to create an ebikes.stackexchange site!?
Questions like "How do I come up with a list of requirements for a microcontroller for my [ebike] project?" hinge upon factors far beyond electrical engineering alone; the OP is asking how to evaluate factors specific to ebikes in particular.
"Forwarding / passthrough UART from one to another port" is a coding question, & probably(?) belongs on stackoverflow, but anyone with experience configuring a variety of "UART programmable" controllers, might know details about coding & components specifically relevant to their (ebike) project in particular.
"Why do the majority of people on an ebike ride at a fairly low cadence?" is a question that really can't be answered empirically, without comparing the results of riding ebikes against manual bicycles.
Hypothetically, a question such as "What criteria are highly significant, when selecting an ebike motor?" has no suitable home I could find on stack sites, right now.
Certainly, any bicycle-focused site may be frequented by some ebike users & technicians, but having a site to pose ebike questions directly to ebike people, seems preferable. (Plus, manual bicycle "purists" might appreciate it, if ebike questions had somewhere else to go?)
I don't think it makes sense to potentially have questions about ebike components get directed to sites that are primarily about manual bicycles, then redirected to the site for electrical (or mechanical) engineering; while datum germane specifically to ebikes in particular, could have a site of its own.
I am happy to follow a proposal to create a new ebikes stackexchange, & would look forward to contributing, but I don't know which other users might also be willing to do so. (I certainly don't want to direct-message strangers, to ask!)
It appears ebikes.stackexchange, will need 4 other users besides me to follow its proposal, for it to be created...
Do any four people reading this want to follow the proposal?
(If not, whom should I ask?)