50-55mph when traffic is clear
in moving traffic 35-45mph will get me through most street traffic lane splitting (CA rider)
below that is just fine, too
its all happy tbh as long as i'm riding and not stuck in traffic. and i am never stuck in traffic when riding
100% urban rider, here. so i am happy at any speed as long as i can ride in between, around, through, and clear of cars, trucks, buses and other things in my way