Taller gearing refers to the gear ratio. 49T spur gear and 18T clutch bell would have a 2.7 gear ratio, 49T spur and 15T cb would have a 3.2 gear ratio. To figure out gear ratio divide the spur gear by the clutch bell. So the 49T spur and the 15T cb will have a "Taller gearing". Hope that helps.