I know the smallest 48p pinion gear I know of is 12teeth . So with the largest fgx spur gear (43t), the total tooth count is 55. Now 55-22= 33 ... In theory, a 33t 48p spur gear should fit the fgx, giving you about 1.80fdr , which I think is too high for a 21.5t blinky that most run with 2.1fdr to 2.7fdr . Using the second ring of the spur gear won't be easy, but it's possible. My biggest concern is clearance issues with the 33t pinion gear ...