Originally Posted by
unterhausen
my touring bike (in progress, story of my life) is going to have a double. Not because I'm particularly strong, but because I don't have a big chainring. The truth is, I don't use super high gears. My crank has a 42 tooth big chainring, which doesn't sound like much but a 42x11 is a higher gear than the 52x14 we all used BITD. I live in the mountains and I rarely find a use for the 11 in the back. This is a pretty common combination on current mountain bikes. My small chainring is a 24 or something like that, but if I ever go touring I'll have something like a 36 in the back. I wonder if this is what the bike shop person was suggesting to the OP. My LBS suggested I go with this combination. My MTB may have a single chainring with the SRAM system. That seems like a pretty good idea.
The bike shop co-op I go to already know this. It is a common request by people who own cross bikes with double shifters and 10 speed at the rear and a number of other shops I know around here know this also, thanks partly to Harris Cyclery for suggesting a 9 speed Deore rear derailleur with a longer B bolt is key. 110/74BCD crank is common and you can get chain rings in different sizes in 110 and 74 BCD as well. The double route is cheaper because the main cost of upgrading the double to a triple are the shifters and when you have a 105 or an Ultegra, few would want a Tiagra or Sora to replace them as triples. However, typically people put a 36 or a 38T rather than a 42T. With a 36T and 11T, your highest GI is 89" which is plenty enough for touring. But again, others will say otherwise. It's like saying you put way too much sugar in my coffee and cream and made it way too sweet. But another person will say it's just right or others will say it's not too sweet. This then becomes more of a personal opinion. But Harris Cyclery and Sheldon Brown had been suggesting anything higher than 90 GI is usually not used for most people touring and they are basing this on sales and general requirement from their customers.
One must separate between personal opinion and real needs from most customers.
Other than that, there are a lot of triple Luddites who are opposed to this. It's a normal attitude when sign of progress threatens the foundation of why the triple came to be. When the triple came out, it too received a lot of flak with strong riders mocking people who ride triples as weak cyclists. But that's just an ego thing, rather than acknowledging triples bring more diverse people who not necessarily have the strength and power into recreational cycling!!
But I sense, it's not what the triple can do, but their opinion must be put as being right even though it sometimes make no sense. And this seemed to be what's happening.