Originally Posted by
pacificcyclist
Wow.. I suppose my touring double Masi is the exception here with a 42T/24T and 11-36. Transitions are smooth and choices are right. I was equally skeptical about this range as well, but the math from the gear calculator suggested otherwise. After last year's tours, I concluded that the range is fine. I own both a triple and a touring double bike so I can compare.
Cheers.. You triple guys are all "always" right!
We basically have the same desired range and also feel a 42t is a good gear for us as our starting point in the center of our wide spaced cassettes. Yours being 11-36 (10) and mine 12-36 (9). I was curious as to what my triple would add to your double so I ran the numbers. Of course we both have the same granny gear a 24t so that won’t change we are both the same there.
Below are your gear inches with the 42t and below I added in the ones you would get if you had the second big ring. Of course you will get one or two higher gears with a big ring but I did the 42t,45t to see what the half step range would be. The additional gear inches are shown in ( ).
I know the ring positions are different on a double than a triple but in my case the chain line was a big factor on the (80),(92),(109) GI. Likewise on the triple the line is very straight on the center of the cassette cogs and those are some common used gear inches.
31,35,40,47,53,59,66,75,86,102
31,35,40,47,(49),53,(57),59,(63),66,(70),75,(80),86,(92),102,(109)
Without changing anything in your gearing you have now except adding the weight of a ring you could have 7 more gears and a much closer spacing. If your spacing now is sufficiently close then all you would get is the 109 GI and if you never have a need above 102 GI and you don’t have any issue making the 24t to 42t shift then the simplicity of a double outweighs the advantages of the triple.