I think you'd need to get some cheap T-Bird cranks if you want a 22t/20t front sprocket, cos it'll have to be a chainring instead of a screw on, due to the size. Cheap cranks aren't that bad, depends on your level of riding though, they won't last long if you do loads of 8ft drop gaps, but if you're just starting out or a bit better than that, it won't be too bad. ORRRR, you could get an 18t screw on sprocket, but that's still smaller than what you wanted. EDIT: Anal, that comes with a 22t chainring? Sweet, OP, that's what you'll want then!