It seems common sets ups are:

a) Triples with 52/42/30 and a 12/25 cassette
b) Compact Doubles 34/50 with 12/28 cassette
c) Regular doubles 39/53 with a 12/32 cassette. (correction 11/32 but doesn't change the question)

Now coincidently (?) all of these have a lowest gear ratio of 1.2 (see attached)

So two questions:

a) When would one need a gear ratio of less than 1.2?
b) Is any of those three combinations preferable in anyway?

You don't even really need gears that low.

36 x 25 is good enough to get up all but the very steepest grades.

34/50 with a 12-28 is for babies and grandmothers.

fify

When you have 20kg of camping gear in your panniers and you're riding up a 10% climb?

The correct combination is the one which gives you the lowest and tallest gears you need while keeping the most common gears you use on one chain ring. Strong riders can get away with using a 53/39 because they spend most of their time in the 53 and will only switch to the 39 when going up hill. If you find yourself normally using the 53 on the flat but needing to use the 39 when its a bit windy or there is slight rise then you may be better off with a 50/34 as it will let you stay on the big ring longer.

Really, the only way to know which is best is to examine what ratios you are using now and then figure what setup will work best for you.

None of those set ups are what I would call common. Lowest ratio required is purely dependent on the rider and terrain to be ridden.

Then we'd be asking the question in the TOURING forum, not this one. Right smart guy?

Simple:
You get the gears YOU need.
Other people get the gears THEY need.

Really I see that combination all the time. Granted I'm looking at bikes under $2K.

I don't think you'll find many people on standard doubles running a 32 cog. 12-25 or even 12-23 are much more common. People who can put a 53 to good use can generally climb in a pretty big gear. Most A (and many B) riders will switch to a compact before going to a wide range cassette. And I'd argue that an 11t small cog is much more common with compacts than a 12t.

My bike came stock with 50/34 11-32. I like it, I'm almost always in the big ring, but there are hills around here where that 1:1.1 ratio gearing keeps me from needing to walk (I'm thinking of one where there's a stop sign at the bottom that's like 20% for a short distance).

I don't see why not, especially when you've got 11 gears in the rear to play with. It didn't even shrink my penis.

Anyone doing a decent length climb with under 3W/kg of power could easily use a 29 or bigger cog in the rear. There's no shortage of overweight cyclists and I'm pretty certain the chubby cyclists aren't climbing with 4W/kg. So I would say a high percentage of cyclists need that type of gearing for climbing hills > 7%.

Thanks, but I'm not sure how to interpret your response.

Are you saying that a gear ratio of 1.2 is fine for climbing hills upto 7% grade?

What 39/53 comes with a 12-32 cassette? Doesn't sound like a very good combination. Does a 12-32 even exist?

Entirely rider dependent. You simply can't generalize this kind of stuff.

He was pretty specific referring to 3W/kg riders.

I'm not chubby, BMI 24 and quite muscular. I squat 1.6 X bodyweight for reps, but I'm 70. So my climbing bike has a 52-39-26 in front and 11-25 in back. I might go to 11-27 this year for RAMROD. Our tandem runs the same in front and 12-34 in back, team age 137. Therefore it's the height of stupidity to go by what other people recommend for gearing. Ride your bike up your local long climbs. If you can't hold an 80 or better cadence at LT, you need lower gears. And some folks climb best at 90+ cadence. If you're looking at big event climbs, you'll need to hold that cadence at no more than say 94% LT or something kinda like that. If you can't, you need lower gears. Plus it's always a good idea to have a largest cog which you never intend to use. You never know when you might make a mistake and start to bonk halfway up a 2000' climb.

IMO if you need low gears, a triple is by far the best thing.

I've heard this segment is a bear.
https://www.strava.com/segments/9137662

I tried this one in my typical 39/23, and it really kicked my butt... Note the extra curlicues by whomever made the segment. I have to work on some prep work before next year.
https://www.strava.com/segments/3884813

But, I agree, even carrying 20 or 30 pounds baggage, one should be able to get up any 10% slope of less than a mile or so with a 39/25.

However, the slopes get a bit rough once once pushes over 15% or so, even for short slopes.

Per Bike Calculator, a rider doing 3 W/kg on a 7% grade would be doing slightly under 8mph. Using HTML5 Gear Calculator we can see that this rider could go up the hill using a 34-28 at ~77rpms, or using a 34-25 at ~70rpms or a 39-25 at ~60rpms or a 34-32 at ~90rpms or... I think you get the idea. Which of those is best is entirely up to the rider.

Yep, I meant to write 11/32 but it doesn't change the question.

39/53 and 11/32 is used because it offers some advantages. I got it on my Breezer after reading these threads and many others. The jist is that combination is great for people (like me) who live in flat areas and do a bit of climbing.

53/39 crank + 11/32 cassette? - Bike Forums
53/39 w 11-32 vs Compact 11-28 - Road Bike, Cycling Forums ...

Seems to me like it gives you a bunch of gear combinations you'll never use (four gear combinations that will give you 27+ mph at 90rpms) with only two gear options for the 18-23 mph range. On the other hand, you could probably spend 90% of your time on the small ring but even then, the spacing doesn't look all that great. But if it works for you then it is all good. As I said, rider dependent.

Last week I climbed for 37min at about 3.8W/kg with a 34/23 on a hill with an average grade of around 6.5%. My average cadence was 85. I'd prefer to be a little higher but was in my lowest gear. If I were to climb a 7% hill at 3W/kg I would need a 31 tooth sprocket to maintain the same cadence.

The climb I did was ranked 411/4200. Someone with 3W/kg would take 47 min (3.8/3 * 37min) for the same climb which would be good for 1945/4200. My conclusion is that more than 50% of the riders going up that mountain could use a rear cog of 29 or more.

BITD I ran a 52/42 with a 14-24 in the back. Over time shifted to the "stylish" 53/39. When I lived in SoCal there were climbs I couldn't do in 39x24. I also had a touring half-step with granny (50/45/28) and a 14-28. That's good for touring and with a set of wheels for off-road I could climb in mtb terrain with the 28x28 setup. I now have an old-man's bike with compact. It came with 11-32 rear but I found I was only using the big ring so swapped out for an 11-26 and 34x26 works for the terrain I ride on. But I could see needing the 34x32 in some situations.

scott s.
.

I have a heart condition. On a good day I don't need gears lower than 30" but on bad days I need lower or I have to walk it in the steepest spot. I also don't really have a lot of use for my highest gears on my modern bikes. Group rides or training with power meters are not in the cards for me.

Racy old 10-speeds in the 70's, like my dad's Paramount, shipped with a gear range 48"-100" so HTFU in low and spin like mad downhill! The shifts were about the same size they are on modern MTB's and they had about seven ratios. A recreational 10-speed was more like 34-100 with six ratios, so the shifts were even bigger.