What does this gear do?

Angel + Devil gear changes from regular to Angel/devil when you get 50 rings. You have to hit gear change when the gear change thing starts flipping over(like a coin). When you hit gear change at a time when the gear change thing is flipped over purple you will get demon, when white or yellow (i forget), you will get angel

I believe that when you transform into Angel, you get better items and you can take air routes. When you transform into Devil, you get worse items, but you speed up. You can not take air routes as Devil. And like zachy said, the symbols flip around like a coin, but angel stays on longer so Devil flips around faster.(Devil=purple, Angel=Yellow) That's just my opinion, but yeah. Good Luck! Sonic, Out!! ZOOM!!!

Well I have just attempted to test the differences between the two sides of the Angel Devil and I have not found much. The Angel side does in fact improve what items you get and the Devil causes you to get much worse items. And unless my disc of Sonic Riders Zero Gravity is bugged somehow, the Devil does not prevent you from using the gear's flight power, all three forms of the gear fly the same for me. As far as actual performance goes I have found very few differences from base to Angel or Devil. The speed counter stabilizes at 159 every time for me regardless of the machine's current form. At the very most the Angel might accelerate a little slower and the Devil may accelerate a touch quicker but other then the aforementioned item changes there is very little noticeable difference between the two sides. In any case the Angel would appear to be the far more beneficial side to choose and the Devil should be reserved for races with friends that you might outrank.

I was just trying the diffences and the Angel gets better items but slows down and the devil gets worse items but speeds up.