I'd love to be able to use in helmet speakers, but I don't know how you use them and wear earplugs, which are a must for me... and then I can't hear the music.
A couple years ago I found this simple way to make custom-fit earbuds, http://boingboing.net/2010/08/27/mak...wn-custom.html. I've tried several of the commercially available custom molded earphones and this works MUCH better than any of them. Plus, you can use whatever earphones you want - spend a lot for better audio quality (I've been using skull candy ink'd, $20 at Best Buy). The molding ear foam is $12 at amazin, http://www.amazon.com/Radians-Custom.../dp/B002CI4CPM.