Nice. I had a similar problem when I rode my bicycle to work daily. I really didn't want to have to carry anything more than my phone.

I ended up hacking a bluetooth earpiece into a remote after seeing the idea online. It was 100% reliable over a period of over 2 years.

Having it mounted in the open like that seems like it could have a few drawbacks. I would still be concerned about water damage, even if you don't plan to ever be out in the rain. What about the fasteners you used? Are they rust-proof? Things mounted on my bicycle that have any metal parts seem to wear out over time, and plastics seem to take on some weathering, possibly from sun.