Originally Posted by
bud16415
Just comparing range of gearing between a double and a triple is pointless. For example I run a 24,42,45 triple with a 12-36 (9 sp) cassette. The case could be made I don’t need a triple because if I were to get a 11-36 (10 sp) cassette adding just that one cog the 11t, I would then get the same top gear around 100 GI off the double (24,42), and assuming I like most here feel anything over 100 is useless for touring what good does the big ring do be it 45t or 52t or whatever it is.
For me the benefit of the triple isn’t about the overall range, I can get that fine with just two rings. For me the benefit of the triple is foremost having almost all my gears I need off one center ring that I feel safe in using without cross chaining in any position. Secondly it’s about a really straight chain line in the highest and lowest few gears, mostly the highest as I can really feel the straight chain line when in smallest 3 cogs on my big ring. The last reason I like my triple over a double is if you need the range of a wide spaced cassette like the 11 or 12, 36 you most likely won’t like the bigger jumps between gears. If you plan your triple correctly the big ring will fill in the gaps. The 52,42 that came on the bike did that as a one and a half step gearing and now my 45,42 does it as a half step gearing. If someone came up with a 15 cog cassette it would be equivalent to the spacing I have with my two biggest rings, but who wants to shift 15 times to go from one end to the other. So in that case I feel there is an advantage to half step and actually 9 might be too many cogs if anything. I think I could live nicely with 7 cogs spaced just right and a half step + granny setup. That’s what I had so that’s what I worked with.
The other advantage I hear other people liking a triple for and the one I disregarded in my setup is some people like the center ring as a transition gear because they feel the shift to the granny might be too hard of a jump. Any setups like that I tried I didn’t like because they moved my most used gears between the two large rings. Others don’t mind that at all.
I view my gearing as a double + granny just like the old days where they talked about half step + granny. I’m not concerned about where my shift pattern is transitioning to the granny range I think it’s at least 3 or 4 steps over in the back. For me that’s a whole different bike when in that gear with a gearing between 17 and 45 GI. When I’m on my normal gears (42,45) that range is 31 to 100 GI with 15 evenly spaced gears to pick from.
Although I disagree that any gear over 100 gear inches isn't pointless for touring...I find a good high gear very useful...your point is the same one that I've been making all along. A compact double can have a range that is close to a triple (it's usually lacking on the low end or the high end depending on ring choice) but the spread is just awful. I view my gearing in the way that you do. I'm more concerned in finding a good gear between the outer and middle rings most of the time and save the low range for hill climbing.
If you look at compact doubles in either mountain or road, the pattern is essentially the same as a double with granny, i.e. 2 separate ranges, except the middle of the range is missing. You could just fine tune with the rear cogs but the transition from one range to another is just horrible. Touring is about the unexpected...you usually don't know the roads that you are riding...and with that comes the expectation of unexpected hills. Many times, I've come around a corner to be faced with a surprising climb and had to start dumping gears. With a triple, you can shift from the outer to the middle ring and transition through the range in a fairly even manner. With a compact double, you'd have to make a huge jump to the inner ring, increase your rpm's significantly, then try to find a reasonable gear on the rear by doing several upshifts. You still have to climb the hill but you also have to futz around finding the proper gear. By the time you've found the proper gear, you've slowed down enough that you need to downshift to the gear you dumped into in the first place. That's a whole lot of fiddling. And you've lost all of your momentum so you'll have to start reaching for even lower gears...which you probably won't have.
I did the Tour of the Moon this fall with my wife. It's not a tour but it is a ride through the
Colorado National Monument that starts with a fairly nasty climb. I wasn't riding my touring bike but my commuter bike which, like all of my bikes, is set up with a triple crankset and a wide range cassette (11-34). I got more comments from people on the first 4 miles...where all the switchbacks are on the map...about how they wished they had my gears. All of them were from people who had compact doubles or traditional road doubles on bikes that weighed 10 lbs less than my bike.