As BeachGuy wrote, you may get emergency care even without insurance, but you may be better off without that "care." in many places, if you do not have insurance, you will be taken to a public hospital and you are just about assured of getting crappy care.
check out allianz travel insurance. i've used them for 5 years. last year i got hit by a taxi in nicaragua and had a fairly severe ankle fracture. they covered 100%+++ of my medical expenses. they even covered wifi in the hospital and all of fiance's in-hospital meals! no bullshit. no waiting. the hospital accepted the insurance after a letter of guaranty was sent over via email!
$400 per year for the executive plan will get you $25,000 in emergency medical coverage plus a whole lot more.
also, do a little research on the better hospitals near where you will be riding. keep a list. find out if they accept the insurance you decide to buy. if you do get hurt/sick, insist on being taken to one of the places on your list if you are near. $20 to an ambulance driver (yes, that's what they are down yonder) will work wonders.