http://www.earfuze.com/store.html
Best money we've ever spent. Use them for racing.
You custom fit them to your ear. Have to mix the stuff, kinda like sillyputty. Then get somebody to help mould it into your ear. Put them in after they've set up, put some duct tape/whatever tape you have on hand over you ear, firesuit mask, then helmet. Can hear perfectly and block out most of the engine noise/noise from the other guys.
Never had one fall out yet from not fitting properly.
Your biggest problem is going to be the cord. I've pulled them out sometimes if I dont have the cord routed properly getting in and out of the car, once im sitting im good though. With riding, and constantly moving I'm not sure how your going to do that.
TL;DR - buy those ones. made of win.