cyccommute 

Exaggerate much? Adding a chainring to a crank adds about 6mm of width. A triple sticks out roughly 36mm from the frame (external bearing) so another chainring is 42mm. That’s not going to make anyone ride bow legged. In addition, don’t current mountain bikes use a 83mm wide bottom bracket so that the bike can work with the much wider rear hub? That’s twice the width of another chainwheel and I don’t hear a lot of people complaining about riding like John Wayne.

cyccommute 

You are missing the major difference between the front and rear. The rear drags the chain to lower gears while the front is far more passive depending on the spring and a momentary reduction in torque to make the shift. Even in the days before the gearing was had sculpted shifting aids, the rear was far easier to shift than the front because the chain is pulled down instead of depending on the spring. The front chainrings now have shifting aids but they mostly work to make upshifts easier which was already a fairly easy shift to make on the front because the derailer pulls the chain up.

njkayaker

The OP isn't talking about triples. Given that the current norm for the rear is 10-12, he's not talking about 4 rings either.

The front and rear aren't really different.

The difference is in going from larger -> smaller versus going from smaller -> larger. These two things work in really different ways.

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When going to a smaller thing, the derailleur positions the leading part of the chain so it hangs over the smaller thing and chain rotation drops (front) or pulls (rear) the chain onto the smaller thing. (The cross piece at the bottom rear of the front derailleur is where the chain hangs from.)

Shifting smaller, the time it takes to complete is related mostly to the circumference.

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When going to a larger thing, the derailleur positions (pushes not drags; well, the rear is sort-of doing both) the leading part of the chain so it rubs against the larger thing and catches on pins (no pins in the rear) and ramps. The chain has to climb up to the larger ring. The derailleur isn't lifting the chain up. Since there aren't that many pins in the front, there is also some extra time to get the ring in the right place.

Shifting larger, the time it takes to complete is related mostly to the circumference and the difference between the two gears (because the chain has to climb that extra distance). Smaller differences shift better/faster.

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Given that the front things are usually much larger, the rotation to complete the shifts take longer.

No, I don't think this matters much.

In the front, gravity exists to drop the chain on to the smaller thing. In the rear, you need the tension (spring) to pull the chain up (against gravity) to the smaller thing.

Note that this dropping/pulling can only happen after the rotation clears the chain off the bigger thing.

It's the rotation that takes the time and the cogs in the rear rotate faster (because they are smaller).

They kinda "faded away". They are much less common than they used to be.

One reason triples were more useful "long ago" was that the difference in size between the cogs was much smaller than it is today. There's been a trend towards bigger differences (in the larger cogs) and the increasing number of cogs makes that more practical. Triples weren't "de rigueur" with 10s. They existed but were unusual.. That the one ring in the front is something that one can consider is an illustration of why triples are less needed than they were (yes, there can be issues with 1X systems).

This is an over simplification.

Years ago, the standard crank was 52/42. This was geared too high for regular people (and many racers). Triples might have been created to add lower gears to the standard 52/42 set up. I'm not sure but it seems, often, the 52/42 was kept and a ring with an even bigger difference (more than 10 teeth) was added as "bailout" gear you weren't supposed to use too often (and that shifted kinda poorly but you didn't care because you didn't use it too often).

With compact cranks and their typical 50/36, the "default" setup became useful to more people (making triples less necessary). Note that the engineering improved the quality of shifts (in the front and the rear) across larger gaps. This improved things especially for the front (allowing for 16 tooth differences to be the norm). This advance opened up more options.

Everybody is using much larger ("easier") gearing than they used to. Including the "racer wannabies".

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There is also the "slant-parallelogram" thing to that improves rears shifting that no one else has mentioned.

(It's also shows that the people aren't doing the "same thing" and are "stagnant".)

rosefarts

When I was maybe 10 years old, I had a Murray 2 speed. Two chainrings up front. It sorta worked. This was in the 80’s. I can’t remember what it used as a chain tensioner but something must have been there.

I got a “real” bike for Christmas the next year and I never looked back.

HTupolev

Although some triples have been spec'd as expansions on the 52-42 double or similar, that's not how they originated.

When 52-42 and thereabouts rose to prominence in the 1960s, it was wider than typical previous racing doubles. For example, 1966 was the year when Campagnolo switched their Record crank BCD from 151mm (minimum 44T ring) to 144mm (minimum 41T ring).
However, this specifically pertains to drivetrains marketed for racing.
Drivetrains in general had long facilitated much wider cranks. For instance: one of the earliest bicycle line drawings by Daniel Rebour, from 1946, depicts a randonneuse with a startling 46-26 (!!!) double. And here's an advert from the early 1930s showing a wide triple in the upper right. The trend is also visible in how derailleurs were designed: "touring" rear derailleurs from the early 20th century were typically built to handle much greater wrap than could be gobbled up by widely-available contemporary freewheels.

njkayaker

I’m not that old!

Maelochs

Right …. And the conversation here is about TWELVE chain rings, not three. So that is 6x12 plus a few mm between rings …. Say 90 mm or well over three inches …. Add the BB width and the same width on the other side and as I mentioned in an earlier post, we are looking at eight inches between the pedals. You might want to ride that bike, I don’t.

Nobody is disrespecting you beloved triples. Many of us still have bike with triple chain rings. Nobody is saying triples are bad or don’t work.

What we are doing is accurately assessing the history we all share, and the physical realities of bicycles and human bodies.

Even when triples were much more common, the double chain ring was the standard (52-42 as a rule.) The standard triple used to be 52-42-32, often with a 14-25 or so …. Which is funny considering the gearing of a (modern popular standard) 50-34x11-28 offers about the same range of gearing ……

That is why triples fell out of fashion---they ceased to offer a significant advantage to a commercially significant number of riders. Nothing wrong with triples—they work just fine and modern triples offer a huge range of ratios with something like 48-38-24 and 11-39 …. You can pull your fully loaded tourer up a mountain.

Nothing wrong with triples … and this thread was never about triples. This thread is about having twelve chain rings. Please explain exactly why You think that is a good idea …. Or just break down and admit you agree with the rest of us. (I know you hate that …. But we still like you.)

PeteHski

OP was asking why not 12x1 vs 1x12? So what about the width of the other 8 or 9 chainrings? Read the context before commenting.

squirtdad

for no other reason than Q factor or how side the crank is.
i.e if you make the crankset to wide it becomes a bio mechanical problem... i.e need to be bow legged and and even then you will end up stressing knees etc