HI all,

Can someone explain the variation in Shimano thumb shifter levers? I have previously always encountered shifters where both of the levers are operated by pressing downward with the thumb. However recently I encountered a low cost 8 speed shifter where the second lever was operated by pulling upward with the index finger. Is there any terminology or classification that can be seen to know which model of shifter operates in which of these two fashions? Thumb and thumb or thumb and index?


Thanks

Mike