acantor (funny, whenever I see your name, I think of as a teenager, I worked at a Cantors Bakery for years...) Im a big fan of triples, my Tiagra fd shifts my 50/39/30 just perfectly well. I even put a new cable on and it was easy to set up and it works flawlessly.
I find I am mostly in the middle ring, up to about 30kph and then I go up to the 50. Loaded however, I would prefer a 46/36/26 or something, along with a 12-30 or thereabouts, and that would give a good low of about 20gi, yet the 36 would still be used for the vast majority of time.

I can kinda understand the idea of doubles being a bit lighter or whatever, but for me the small weight diff is nothing compared to being more flexible and having tighter jumps between chainrings. Plus with the case of my tiagra fd, as I said, it just shifts perfectly well day in, day out and was easy to set up, so I see no giving up shifting ease in the equation.

The idea of a double touring crank appealed to me also at one point and I remember discussing this idea with nun and others of using a triple crank and leaving the big ring off. Like him I found the 42t center ring to be my go to gear for all but climbing steep hills. I first went from 30t to 26t and now have found 24t is not that bad a shift off my 42t. I went with a 12-36 (9 sp) cassette as mentioned above to get the biggest spread of gears and spacing is fairly even but sometimes the jumps left me wishing for in between cogs. I thought about first losing the 52t big ring then I looked at replacing it with a chain guard, then I thought about sizing it to something smaller as I couldn’t see needing 117 GI top gear. The more I analyzed the big ring I saw the 52,42 gave the closest to half steps and I started using the 52 that way. So leaving the 52t gave me at least 5 gears I didn’t have and they are right in the middle of the most common used gears.

So even though I liked the idea of a double the weight of the extra ring for me was a good trade off to get closer spaced gears when I needed them.

I think that an ultra compact double starts to make more sense when you have a very light load and can get by with a narrower range cluster on the rear. For me it was fine and I was even able to use a short cage derailleur, which I considered a plus. I didn't go that route until my base load was 15 pounds and found it more applicable as I went lighter still. I do not know that I would go that route with a much over a 20 pound base unless it was flat land touring.

My use of a double has nothing to do with weight. I found the chain angle on my most used gears was not optimal when using a triple. I was in the "Goldilocks situation". 50t just too big, 36t just too small, 42t just right. I have no need of gears above 100" and found that I mostly used a ratio around 70" and that a 42t chain ring coupled with a 11/34 cassette worked nicely.......It does have the issue of having even more chain angle than a triple at the extremes of the cassette, but I seldom use those and my most comfortable gears now have no chain angle and I don't find myself continually shifting between big and middle rings.

The MTB cranks coming out with 42/26 and 42/28 rings look good for touring.

I have a Nuvinci rear hub. It has a nice, wide range, and I couldn't find a good use for a triple given that every gear could be replicated by either the smaller or larger ring. I was only shifting when I was running out of gears at the top or low end, and that didn't happen very often. So 34/48 double is what I think I'm running, giving me the lowest recommended gear for the Nuvinci and the largest chainring I can use with the chain guard that I haven't gotten around to getting yet.

Nuvinci has a wide enough range, and I was shifting so infrequently, that I removed the front derailer, so while I'm technically running a compact double, in reality the bike stays in the big ring for daily commuting, and when I load it up and hit the road, I manually move it to the small ring until the trip is over.

I'm very happy with the double, but then if I was running a cassette, that might change. As it is, there's no real worrying about optimum shift patterns, and the chainline is always just a little shy of perfect, but that's all thanks to the hub gear.

Ironic. During the four years I lived in Montreal (as a teenager), many people asked me whether I was related to the owners of Cantor's Bakery. (I'm not.) But in my early- and mid-20s, I went on to have a (brief) career as a baker in Kingston.

About the only connection this has to this thread is that I bought my first touring bike (a Motobecane with a double) from my earnings as a baker! And I struggled getting up steep hills....

nun, funny you mention chain angle because this is something that I have always been rather attentive to, not wanting too much chain angle as it just didnt seem right (as in efficiency and wear on stuff) and so I have found that a triple is actually quite good for chain angle and another reason I likem.

In the 39 ring, I avoid using 1st or 2nd (on a 9 cassette), in my case on my tricross, 32t and 28t, and also avoid 8th and 9th, (12 and 11) and will move to either the 30 granny or the 50 depending on which way I am going, specifically to keep the chain angle straightish.
Also, in the 50, I dont like using anything lower than 5th and up (18tooth+) and in the 30 chainring, I tend to get out of it when I get to about 5th as well.

In my daily riding with less weight on the bike (10-15) this is pretty much how I shift, and my perception is that the chain angle is always kept pretty good.
With more weight on the bike, I won't get into the 50 unless a pronounced tailwind or downhill presents itself, but again, with a 39, Im good on the flat to high 20kphs and Im still not using the 12 or 11 cogs--and for me, the vast majority of the time Im mosing along at 15-25kph.

My old mtn bike has a regular old 42/32/22 and a 11-28 (8 speed) and with loads of stuff on it, there is less back and forthing between the 42 and 32, and in the 42, I never go below 5th (16tooth) as I find the chain angle in the 18tooth (4th) too pronounced for my taste.

as you say however, not having to continually shift from middle to large chainrings is a big plus. As I explained, the 39 middle in the 50/39/30 is really versatile, but I see how a 42/26 would be a really good setup-with a 11/34 cassette. That said, I am fond of tighter jumps such as the 11-28, and I could see it being even tighter with a 9 speed or 10 speed.

gearing is neat to discuss and see other peoples takes on it. I do think that an individuals preferred cadence and such does make a diff for all this, I dont have beefy legs, so tend to prefer lower gearing than others who are more comfortable at slower cadences as they have more torque than me.

The Cantors Bakery I worked at was in Ottawa, and I used my earnings from that to buy a motorcycle (Kawasaki 175 enduro, with five speeds!) and it struggled to go faster than 115kph and shook like a leaf at that speed...

I agree if it’s a double you want for touring a triple crank setup with the outer ring removed will give you a good chain line off the center position. I mostly stay in the center of my cassette 5 cogs also and that came about as djb and nun pointed out by finding my optimum center, center combination. In my case that’s 42t front and 21t back and with tire size factored in 54 GI. I don’t try and avoid the other 4 cogs though when working off that center position I feel all the cassette is fair game without thinking of it as cross chaining. The big difference with a double touring and a double road is I think the touring setup is looking at that smaller chain ring as a bailout granny for getting up hills with lots of load and I want that range to be below 20 GI by as much as I can and still keep on two wheels. In my case that was 18GI. Where road doubles are sharing the main gears between rings more. I kept messing around with my cassette because even though I needed a super low gear I wanted a range of gears while shifted down there so I didn’t feel the need to jump back to the center ring too soon. The wide spaced cassette helps with that because I feel good with the 6 biggest cogs when on the granny gear and have a range between 18 and 36 GI to pick from.

So for me the wide spaced cassette solved several problems it lets me have a wide range off the center without a front shift and allowed for a super low creeper gear but also 4 other good low gears (unlike the mega-range cassettes). The drawback is what djb also points out, with day to day riding around town it leaves you wanting a closer cluster. That’s why I left my third ring on as a one and a half step to fill in the gaps when needed. It is some fooling around though doing double shifts with the rear shift being a two cog shift and its complicated enough I only want to think about doing it when I’m searching for that in between gear when I’m looking at a stretch of road where I will be in it for a while. I’m seriously thinking of going to a true half step up front with a 45,42,24 for this reason. I have been talking about how to best do this on another thread over on the BM forum. Rather than doing it here as this thread is about doubles.

This is an interesting idea. However, I don't really mind the large gear inch jumps of a super compact double and an 11/34 cassette so I've never bothered with half step. Mostly I just find a triple more complication than I need. In fact with the new 11/36 cassettes I can see a single 36t front ring working well. You'd have the following gear inches, which don't suck.

88.36
81
69.43
60.75
54
46.29
40.5
34.71
30.38
27

I could see that working quite well for me. It would be pretty close to the range of the double setup I used on the ST and I was happy with that. I think the spacing looks fine as well. It would mean having to go to a long cage derailleur, but would allow skipping the front one. If I were going to set up a more modern bike than the 7 speed stuff I have been using on my recent tours I would definitely consider something like that.

I don’t know if I would call it a super compact double or not but on my Cannondale road bike I put a mountain triple minus the granny gear. Kind of the reverse of what we are talking about using a road triple, without a big ring as a double. So on that light bike I have a 32,42 up front and a 13-24 in the back. And that gives me a similar range 35 to 89 GI. I love riding that bike and if I was light myself and able to tour ultra-light maybe that would work. So a single 36t chain ring and an 11-36 would be better. But on a touring bike and knowing my abilities a 27 GI low wouldn’t be enough. Now if I could have that on a light road bike, I think would be great.

This discussion pretty much confirms what I have always felt and that is how personal gearing becomes. Both the rider and the location.

The chain angle wouldn't be great at the extremes - the ring would be centered on the cassette so you'd have to go across 5 sprockets, but it's intriguing

I wonder how much the chain line issues would be noticeable. I know that there are quite a few mountain bikers going with a 1X10 these days.

happily using a double on my rando rig that i use for lite touring, and on my fargo that i use for bikepacking.

30/44 or 30/46 on the IF, with currently a 13-29 10 spd rear, but I'm likely moving to 9spd on that bike soon.
currently running 28/42 with 12-36 10 spd rear on the Fargo. on the road i stay mostly in the 42, but i do drop to the 28 when on a trail, steep dirt road, or am not feeling it.
i'll likely change rings when i wear them out and go a bit lower on the front. 26/39.

i've been tempted to go 1x10 as well. i haven't studied the range i'd want, but i'd aim for the low end.

I made the pilgrimage to my two LBS on Friday asking about a 45t 130mm 5 hole chainring. They both found a pretty expensive road bike ring that was out of my price range. They didn’t see any issues with getting my 10 tooth jump FD to work with a 3 tooth jump after I mentioned the potential problem and then explained it to them. I then asked if they could order me a BMX 110/130 BCD ring and if that would even work. They didn’t seem to have an opinion on that but found me one for about $50 that would take 2 weeks to get. I didn’t ask about the install charge.

I went home and found this on Sheldon Brown on the subject of these rings and usage with a derailleur.

http://sheldonbrown.com/harris/chain...30.html#rocket

Did a Google and found this similar ring for $14 that I could have in 3 days. So I put it in the shopping cart and it should be a good way to experiment without much cost.

http://www.amazon.com/Rocket-10H-BMX.../dp/B0011FYHZC

If it doesn’t work I can always use it on a single speed build. Should know in a couple days.
My Granny without cross chain will give me this GI range. (6 gears)
17.7
20.0
22.8
26.6
30.4
35.5

And my main rings with half step will give me these without cross chaining. (15 gears)
31.4
35.3
40.4
47.1
50.5
53.9
57.7
62.8
67.3
70.7
75.7
80.8
86.6
94.3
101.0

Not to hijack this double ring thread. Once I get this ring on and ride it a bit I’ll take a few pictures and start a thread if there is any interest.