Whatever happened to the 4 x n derailleur drivetrains?

Question

Around the mid-1990s I am positive I remember seeing bikes with 4 x n drive trains e.g. 28-speed (4 x 7 gears).

There is nowadays a trend towards just 2 or even 1 front sprocket e.g. 1 x 12. More than 3 front sprockets I have not heard of for yonks.

What happened to the 4x front chainring? Why did it disappear?

Answer 1

I had a MTB that had a quad chainring. The bike was a Raleigh Delmara and it was equipped with a friction shifter. Photo is dated 2017, but it was ancient at that time, probably late 90's steel MTB

From memory it provided no more range than a triple, because the difference in tooth count betwen chain rings was not as much. That is, it was more like a triple that had two middle rings splitting the difference, rather than more range in the ends.

There were no indexed shifters available for it either, but friction shifting worked fine. The front derailleur was a normal triple mech, so the chainrings were slightly closer together. Ultimately mine was a Raleigh experiment, not a groupset.

In the end, the problems solved by more chainrings would have been addressed better by larger cassettes, and that's what most bikes have now. A single 10-50 tooth cassette with a 42 tooth chainring has roughly the same span as a triple with an 11-30, and adds simplicity while removing weight. The only loss is in the total number of gear combinations (which was more for marketting than for real riding)

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@andrew makes a great point that the rise of ramped and pinned chainrings made it much easier to use greater differences in size between chainrings. As you can see, these chainrings have no ramps, so a large jump would be slow to actuate, and potentially fail causing the chain to drop.

Answer 2

Here's a review of a 4× adapter (which apparently you can still buy). I also know that there's a specialty tandem drivetrain, Davinci, that uses an interesting 4× setup.

I've never heard of any of the major component manufacturers putting out 4× drivetrains, even as prototypes, and I think that's because it would always be a niche product. Many naive riders are flummoxed by two chainrings, and don't understand how to shift through a crossover pattern correctly (never mind half-step). Adding sprockets in the back makes it easier to shift through a wide range of gears with reasonably close and consistent steps. Also, after you've added enough sprockets in back, it becomes reasonable to remove chainrings in front (my 2×9 bike has 12 distinctly different gears, which could now be achieved with a 1× setup).

Conversely, a 4× setup is only going to appeal to a rider who A) needs an extremely wide range of gears, and will not put up with wide steps between gears, and B) is willing to make the mental effort to avoid cross-chaining situations.

Part of the problem with 4× as a commercially viable product is that it would need to work as part of a system; in order to really benefit from the potential gearing range, the rear derailleur would need to be able to wrap up a huge amount of chain to maintain adequate tension—no major component maker would release a drivetrain that relies on riders intentionally avoiding cross-chaining. Also, the effects of cross-chaining would be exacerbated, and riding small-small could easily result in the chain dragging across the big chainring (The DaVinci avoids this by having smaller "chainrings" that are farther from the rear hub, so the chain's angle of deflection is reduced).

Although I doubt we'll see it happen, the advent of electronic shifting that figures out the right gear combinations for you could make different gearing—such as half-step gearing or 4× gearing—more appealing to a wider range of riders.

Answer 3

When I got my first geared bike (it had 3×8 speeds if I remember correctly), I was perplexed to learn that there were two controls (left and right shifters) to perform a single function (change drivetrain gear ratio). I figured it was dictated by limitations of technology of that time. It was not hard to use two shifters; it just felt… inelegant. Unexplainably, I never considered two brakes controlled by two levers to be illogical.

I was pleased to learn about one-by systems which were already available, and I switched to one soon and never regretted it. Now, if only gearboxes were as cheap and widespread as 1×, I'd switched to them.

But essentially, all bicycle gearing systems have a number of compromises to make. For example, current 1× systems have worse chain angles in extreme positions, and often larger jumps between gears So they are not all-around better than multiple-chainring systems. It seems that a 4-front chainring system collects too many weaknesses of other gearing systems to have marketable future.

Let me compare 4× against 1×, 2× and internal gear boxes (or hubs, later abbreviated as IGH).

1. Weight is worse than 1× and 2× systems, but potentially better than IGH.
2. Possibility of operator error causing cross-chaining is same or worse as with 2× systems, not an issue with 1× or IGH.
3. Achievable gearing range is the same as with all other existing systems (1× have up to 1:5.2, IGH have 1:6.0 or lower).
4. Maintenance costs of front derailleur same as 2×, non-existing with 1× and IGH.
5. Shifting crispness — same as 2×, not an issue with 1× and IGH. Shifting at front chainrings happens with the chain being under tension, compared to the rear derailleur where it moves the lower section of the chain, which is not tensioned.
6. Ground clearance — worse than all other systems (important issue in MTB)
7. Q-factor — worse than all other systems (a stack of chainrings pushes the cranks farther out)
8. Pedaling power losses — ? really hard to tell without actual measurements.