I have the Bose IE and while they sound good (a lot of people disagree with me on this...) they do not isolate at all. Great for some things, not so great for riding.
I also have Shure E2c and SE210. The E2c are somewhat large for in helmet use, and the included tips are not ideal (foams work well but don't last very long, "flex sleeves" are not that comfortable for me). Sound pretty good though, especially with a few mods. The SE210s are much smaller, sound better, and come with better tips - I would recommend these of the ones I listed. I have never worn any of them while riding though, however I do wear earplugs (Etymotics) if I'm on the highway for any extended period of time.