Besides what you mentioned:
Color, type of bike (road, mountain, hybrid), suggested height of rider ("for short riders"), frame tubing - specific ("Reynolds 531") as well as material ("steel," "aluminum"), classic/vintage, lightweight (if really lightweight, don't append to every bike), just to name a few.
I use up every character of the CL title if possible. Two reasons: To squeeze in more keywords, and let folks read right in the title whether the bike might fit them. For those not familiar with frame sizing, "for short riders" is pretty well understood, and in the post, I'll give more details: "Suggested rider height 5'2 - 5'5."
Is there a way to include keywords other than in the title? Sure, lots of folks do this at the end of the posting, in order to try to grab views outside whatever they're selling. So if they're selling an Italian road bike, they'll list every Italian manufacturer that ever existed in addition to the one they're selling. I don't do this. I keep my keywords on point.