I'm glad to see you active after your back problem! I also love cycling because it's low impact (until I crash). Nice bike, too! Looks very good and light! Mine is definitely a bit heavier but 21 speed as well and, yes, I can also say that that middle sprocket is a good sweet spot! I just bought another water bottle holder the other day because, like your set-up, one is not enough!

The course you followed is beautiful and seems relaxing. Your skyline reminds me of my lakefront trail.
I've been curious about visiting Viet Nam... even moreso since my sister said she had a great time during her solo trip there recently.