I use wired earbuds, cheapies from Lowes or Home Depot or wherever. If there's traffic I'll drop the left earbud out. I usually listen to spoken-word podcasts, but a couple weeks ago I loaded up a bunch of old music MP3s from the Napster days and rode with that. That was a very very very very good ride.
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Kitsap you're right, it's a safety compromise. If it feels like the wrong time or place I won't do it.