The proper answer would depend on a number of variables: all based on the Low & High ranges required and a rider's tolerance for steps between cogs, budget and aesthetics.

Select the lowest gear that will get you up the stiffest local climb w/o undue stress & the highest gear that you are willing to spin-out on the other side.
Now you have your Low & High range defined. Cram as many cogs in the back & chain rings up front to suit your self and have at it.

It's a personal thing, but getting the Range dialed in is critical.
With modern cassettes having a Flat, Rolling & Mountain cassette to switch out as required is a 10 minute job, considering the expense of current machines a good investment in performance for few $.

-Bandera

Yep. That's the nice thing about cassettes that can change the range alright.

I am 70 and like a compact double for most riding situations, however when planning a hilly trip I take a bike with triples. I just regeared one to 50/39/30 with 11/30 cassette.
I spend winters in Austin TX, where not uncommon to see compact doubles with 11/34 cassettes. Lots of hills, I have a bike there with 46/36/26 and 12/28 cassette, 7 speed.

The decision between a double and a triple is driven as much by marketing/engineering decisions by Shimano/SRAM/Campy as it is by what riders actually need. Compacts are easy to find and work well with brifters. Shimano's triple, IMHO, is a poor design that doesn't offer much of an advantage over a compact. SRAM went over to compacts a long time ago and Campy is expensive.

A triple with a 110/74 bcd (and those are getting harder to find) gives you the best of both worlds as you basically get a compact with a bailout gear. Plus typically the big 2 rings mimic what you see on a modern cross bike (48-36 or 46-36) and that works better, I think, than the 50-34 you find on a compact.

+1 a 48-36 chainring set with a 12-30 cassette is ideal for hilly rides and a 46-36 with an 11-28 cassette also has merit for the recreational 50+ cyclist who is seeking a wide range and user friendly cog spacing in the important 15 to 30 mph range.

Baloney. A 39 chainring with an 12-27 cassette has a faster speed range than a 34 chainring with an 11-2X cassette. The 34 chainring 11 cog combination provides 23.2 mph while the 39 chainring 12 cog provides 24.4 mph at the same cadence and tire diameter. Also, a triple with a 12-27 provides both a wider range and tighter cog spacing than a Compact with any available 10 speed road cassette if a 26t small chainring is installed.

How do I know? I installed an Ultegra 50 -34 compact with an 11-32 (11,12,13,15,17,19,21,24,28,32) Sram road cassette with an Ultegra long arm rear derailleur more than 4 years ago, it was only useful on very hilly routes and a total pain on faster rides on flat roads.

See: http://www.bikeforums.net/long-dista...r-no-hill.html

The 11 to 30 cassette you use to justify your opinion doesn't exist and wouldn't be an improvement over a road triple and a 12-27 cassette. You would likely end up with a 15.4% change in cadence between the 13 and 15 cogs right at the 20 to 23 mph cruising speed while on the big ring. A 11,12,13,15,17,19,21,24, 28,30 would not result in a better hill climbing range than most road triples.

Returning to reality, we see that the popular Compact and 11-28 cassette combination is inferior to the 52, 39 & 30 triple with a 12-27 cassette. The triple provides both tighter cog spacing with a very usefull 12,13,14,15,16,17,19 block that can be used from 15 to 33 mph. Please click on the image below.

http://bikeforums.net/attachment.php...hmentid=408982

I'm not using an 11-30 cassette to justify my opinion. I am using 5k miles this year with an 11-28 and a few hundred with a 12-30. I don't own an 11-30 10 sp, had a 9sp with that but whatever. One the one hand you seem to agree with me with your paragraph above the quote. Speeds below 22 miles an hour for me I do not need a big ring, your chart shows that nicely. Around 17 miles an hour I can move to the big ring. I've not found holes in what I have and can always seem to find the gear and cadence that fits how I feel and how fast I want to go.

Well, your revised opinion is correct, anyway. We both agree that a 50 & 34 compact requires changing the front chainrings in the common cruising speed range of 15 to 20 mph. A 39 chaining easily allows the cyclist to stay on one chainring and to just use the faster changes across the cassette until 24 mph or faster speeds are reached. Most 50+ recreational cyclist are infrequently reaching cruising speeds above 24 mph, where exceeded 20 mph happens with greater frequency.

Chances are that gravity is aiding your gearing. A 50 chainring works well if traveling downhill and even a 1% slope can make a difference for a heavier rider. A 34 chainring works well while climbing a moderate grade, although a 30 or 26 is clearly better up a truly steep grade. However, roads that stay in the plus or minus 2% range are much better on a 39 or 42 chainring if the cyclist likes to maintain a 15 to 24 mph speed range. One of my vintage bikes uses a 52, 42 and 30 chainset with a 12-21 cassette and the middle chainring is good up to 26 mph. That's a sweet ride;
http://i289.photobucket.com/albums/l...psab71db9e.jpg

http://i289.photobucket.com/albums/l...ps012b14aa.jpg

To muddy the waters further, there's this sub-compact crankset from Sugino:

http://bikeforums.net/attachment.php...hmentid=409000

It has 74mm and 110mm BCDs, and is compatible with Shimano external (road) BBs.

I have an older triple with 50/45/28. I find the 50/45 gives plenty of options while cruising and the 28 is there when I need it (using 14-28 out back).

scott s.
.

Love the design, hate the price.

Interesting.

Is there some fundamental reason for not having the gap on the cassette.

It looks like a 34-48 coupled with a 12,13,14,15,16,17, 22, 25 28,32 would give you a one tooth increment all the way from about 13-28 mph, one shift on the front, with a very narrow cadence band from 80-85 rpm, and Skip the small ring with the small cog.

Would the 17-22 jump in the middle play havoc with the rear shifter?

.
Other than your reading comprehension and your mistaking my words we do somewhat agree. Can does not equal require and my opinion has not been revised. I think I confused you by talking about two different bikes both with double cranks, my road bike and my cx bike.

As with most folks gravity works both ways. I do my share of inclines and declines and even more of into the wind. I climb mountains with my lowest gear of 34-28 and 36-30 on two differing bikes. Grades measured in miles rather than feet long and at 6%+, some as steep as 13% sustained. If gravity did not work against me so much I would be rocking a mid compact plus my 11-28 but sometimes I like the lower gears and am unable to out spin 50-11.

I'm 63 and here in Texas you don't have any hills per say, however where I live we have what I call rolling hills, landscape.

Both my bikes have a double

a. Ridley has sram 53/39 with a 11-25 cassette.
b. Tiemeyer has shimano 50/36, the smaller 36 ring is sram and shifts great with an 11-23 cassette.
I can ride and push all the gears with really no issue. However with the arthritis I have my preference has been leaning towards the 50/36 for more spinning and just seems to be more joint friendly.

My road bike is a 92 Paramount (7 speed downtube originally) which I refitted with a 50/34 compact and a 12-32 rear with an XT rear D/R. With 9 speed Ultegra it shifts flawlessly.

That's my solution to old knee, one of which is metal, and Texas hill country.

It's a simple thing to change rear cassette and rear D/r, and probably cheaper than a new crank.

Just sayin'......

Boys I think you're differences depend on riding style and what gears you like. As a non masher type I'm personally all over the gears front and back just to keep up with the Joneses. I can go back and forth on the chainrings and RD several times in a few rolling hill miles and will trouble to do so. Some people like to pick a ring and stick with it.

I know when to ignore offensive or contradictory statements. Reading comprehension? Another statement to ignore. My climbing includes the same stated range as you, but anyone would be hard pressed to find a steeper or longer climb than this 5400 ft climb in less than 18 miles;

http://www.mapmyride.com/routes/view/411922326

http://www.bikeforums.net/fifty-plus...ean-coast.html

Even my century rides in Wisconsin include 15% climbs: http://connect.garmin.com/activity/356683768

44/34 front.. 13-26 rear.. 8 cog set. Will do 25 mph+ spinning... with 34-26 I can handle any hill near me. If I had to do real climbing I'd mount a 28
in the 3rd crank position.. which my crank has (those holes now filled with grease). Wonder if a adjustable BB would handle a 2 or 3 ring group up front?

Most of my mileage is between 15-21 mph.. who needs the big number up front.

Thanks for all the great replies. It's rather flat here in Richmond, Virginia. So I don't see that need for a triple. A common 34-50 compact double would serve well along with a simple (also common) 8 speed cassette, maybe 9 if I want a little more variety. Just want to keep it simple... Nothing fancy...

13-26 as a nine only means of the addition of a 16.. which means little of nothing. 12-something nine again only adds high end gearing used mostly with a strong wind trailing or down a hill.

8 chain is a mite stronger.. 8's are easy to adjust for nice shifting. Components are reasonable too.

Here on the east coast there are no flats. Neither are the hills very long, just up and down all day.

I love my triple 28 - 38 - 48 with a 11 - 28 7 speed!

Double. Too much redundancy with the triple. If one were to do lots of mile long hills with baggage, maybe, but double in every other situation.

Actually I don't see any overlap as I only use 28 - 24 -21 with 28, 24 - 21 - 18 - 15 with 38, and 18 - 15 - 13 - 11 with 48. Probably a bit excessive on x-chaining avoidance but very good consistent shifting. Works for me.

I have a similar set-up, with a 48, 36 & 26 crankset and a 13, 14, 15, 17, 19, 21, 24 seven speed freewheel. I'm very pleased with the 3x7 divetrain. It lacks a little of the range of my other bikes, but works great on rolling terrain.