Generally the most common gear ratio is 22:18, but sometimes can be a little bit to hard depending on your riding style, some people use 22:19 although if you are in to saveing weight you can have practcally the same ratio as 22:18 in 18:15 which is very slightly easyer, this is becomeing alot more common nower days and seems to becomeing the stander on most good trials bikes. finally i think its 16:12 which is used by people who run a midleburn super pro trials guard, again saveing weight and being able to have a easy enough gear to ride trials. Will