Besides the blog, you can find interesting stuff in the source repo, in the technotes and RFC dirs:
https://github.com/cockroachdb/cockroach/tree/master/docs/te...
https://github.com/cockroachdb/cockroach/tree/master/docs/RF...
There's also a bunch of technical tech-talks linked from our company's website: https://www.cockroachlabs.com/community/tech-talks/