http://rmgo.org/faq/#OpenCarry is a good resource.
Open carry is legal in all of Colorado, except Denver City/County. You can't carry within 1000 feet of a school, according to federal law (enforcement doesn't seem widespread, if at all). You can carry on your motorcycle any way you like -- concealed if you choose. You just can't get off your bike with it concealed. You can carry loaded.
You can carry in places that serve alcohol. You can't carry while intoxicated.
That's about it -- public places have to be posted against open carry, and private property owners can ask you to leave.
Edit: You can't carry loaded on public transportation.