kyselad

This is sort of a shower thoughts question, but why do bikes favor large numbers of gears in the rear vs the front? I understand why many prefer 1x setups, but when I underestimate a climb and need a bailout gear fast, shifting to a smaller chainring is just mechanically easier than having to push up to a larger rear cog.

I’m sure there’s a good reason that we have “1x”instead of “x1” and that rear clusters almost invariably outnumber chainrings, but I’m just curious what that reason is. Would the right foot hit the chain line? Something else?

Velo Mule

It pretty much comes down to mechanics. It would be difficult to put a cluster of gears on the crank. The other issue is that when shifting the chain on the front derailleur, it is under tension whereas when shifting on the rear the chain is slack. The most we see on the front is three chainrings.

Now with that said, we could get a three speed bike with these three chainrings, but we will still need a derailleur like device to take up the slack.

There are some bikes designed with internal gearboxes in the bottom bracket. Whether this qualifies as a n x 1 is up to you. The only one that I know of is Pinion. There might be others. Shimano has a patent on a system using chains, however, it is not available for sale. Neither is/was the Honda.

urbanknight

I imagine there isn't enough space to fit that many gears up front without riding bowlegged, and chainrings are bigger and therefore add more weight for each additional gear.

I wonder if you could make an internal gear bottom bracket.

PeteHski

The rear derailleur is lightning fast and efficient at changing ratios, especially modern ones. The front derailleur is still relatively slow and clunky in operation, especially going into a higher gear. Do you really want a stack of 11 or 12 front chainrings with a super-wide front mech? The less chainrings, the better in my book.

kyselad

Certainly with the current mech, it’s a non-starter to put the cluster up front. The question is why we haven’t developed the tech the other way around.

kyselad

I think the chainring size is probably the main point. We can only go so small for rear cogs, meaning the lower limit for chainring teeth still leaves us with big chainrings in order to hit reasonable gear ratios. A “front cluster” would need a lot of teeth, making it very heavy and also requiring a derailleur with a huge capacity due to a large difference in absolute tooth count between the low and high end.

PeteHski

Simply because the rear derailleur is inherently quicker and more efficient at swapping cogs. The tech has been developed as best it can for both. The front mech is IMO a crude device, which is why the industry is slowly moving away from them. I predict they will be history within the next decade. There is zero chance of the industry moving in the opposite direction toward Nx1.

PeteHski

Width is another major factor. We would all have to ride like John Wayne.

There isn't really a lot going for the Nx1 concept, which explains why it isn't a thing.

skidder

You think so? I'd think we'd look more like a cowboy in Blazing Saddles, or maybe Buster Scruggs.

skidder

I've got one, its a 2x1; two-ring chainring (52/34) with a 16T single speed on back and the RD is now a dedicated tensioner. Works great for the occasional hill in my area. But weight saving is practically 'nil' vs the original 2x6. Bicycle was originally a Schwinn LeTour 2 from the late 1970s that I got for free.

Camilo

Others have described how a multi chain wheel would be impractical. But, the triple crankset solves that bail out problem. Just getting a bail out gear in front - going from a larger chain wheel to a smaller- is very quick and easy with a triple. Going to a smaller sprocket or chain wheel is mechanically easier and quicker and the triple crankset provides that, at least to a small extent. But "they're too hard to adjust" (BS), they're too heavy (a little heavier), but mainly not fashionable.

big john

As mentioned, Pinion makes a 12 speed internal gear transmission.

kyselad

For sure I could see a 2x1 or even 3x1 is doable with existing cranksets. I was more thinking about getting the range approaching that of a typical 1x drivetrain. Given the chainring sizes that would be required, the drivetrain would need an insane capacity to handle the difference in tooth number required for even a modest gear range.

kyselad

That’s honestly super cool. I was specifically thinking that the front is mechanically easier than the rear for shifting to a lower gear with a derailleur drivetrain. Not sure if an internal hub provides a similar advantage for front vs rear of the drivetrain, I only know that the workings of internal hubs is above my pay grade.

big john

It has a 600% range, which is huge, it makes the rear wheel lighter since there is no cassette or derailleur which also makes the suspension easier to activate. It works for backcountry type riding since you don't have to worry about bashing the derailleur on a rock.

It would work on a road bike but it adds weight and is said to drag a little in certain gears/conditions. It's pretty tough to beat a derailleur for versatility.

Leinster

It exists. I do not know why it hasn’t been adopted more broadly.

https://www.efneo.com/gearbox/

Gresp15C

The rear derailer functions as both a gear changer and chain tensioner. And the mechanism is on the low tension side of the drivetrain. The conventional front derailer still requires at the minimum a chain tensioner to function.

Thinking about gearboxes, maybe putting them in front ultimately makes more sense because you can put as much stuff in an expanded bottom bracket case as you want. But there's also more torque in front, and frames have not been standardized to receive front gearboxes... yet.

If there was a cheaper way to put a bunch of gears on a bike, we'd see it on cheap bikes.

PeteHski

I hated mtb triples and find 1x mtb drivetrains infinitely better. For road bikes 2x12 is more than enough range for me. Triples made more sense when there were a lot less rear gears, especially on a tourer. But I’d rather have more rear gears for a given range.

Modern drivetrains shift effortlessly up or down. On rides I do still see plenty of guys ranting their gears on steep climbs, but that’s just poor technique.

So I’m happy the way drivetrain “fashion” has gone in recent years.

spelger

crude in what way?

Maelochs

Fashion is not really part of it ... they simply are not necessary for most riders. With 11 or 12 cogs (versus five or six) it is easy to have a wide range of ratios with a double chain ring (or even a single) and with modern indexed shifters, easy to get to any of those gears even under load.

The added ratios a triple would provide are beyond what most riders would use, and since rear shifting is quicker and easier, there really isn't a necessity for a triple .... maybe for touring, where a rider might want a really low option for hauling full kit up mountains, but for most riders, a triple offers no benefit over a double.

Also, with front derailleurs now handling a 16-tooth spread (or more) as opposed to ten .... (standard 10-speed gearing was what, 52-42x14-34? or maybe 12-25?) I toured flat lands with a 52-42-32 triple and a 34-toorh big cog. Now I can ride a 50-34 with 11x36 and get almost the same range. Only for mountain touring where a 22-tooth chain ring might be needed, can I see a triple really paying off any more ....

Back in the day when cross-chaining was a real issue and a six-cog cluster was cutting edge, a triple really made sense for a lot of applications. Not so much any more. A modern 1x12 offers 12 usable ratios ... and old 2x6 maybe offered eight (with high-low and low-high excluded due to insufficient chain flex, and some overlap with ratios barely different.) A 2x11 probably offers 14-18 distinct and accessible ratios.

I think triples fell out of fashion because most riders simple never used the small ring once they got seven or eight cogs in back.

79pmooney

The RD's 90 year head start is hard to overcome. Q-factor (width distance between pedal-crank interfaces, right and left) would increase though maybe not as much as it would seem as there is not FD above the chainrings the crank has to clear and the chain in the outermost cog combo angles in toward the rear cog.

I've been running a triple on my Mooney to run with 3 fix gear cogs, two on one side of the hub, one on the other. Chainline is barely over the track standard (about 1mm) and Q-factor running old straight cranks is very low. (Shifting mechanism can be found sitting on the seat. Rider using a Pedros Trixie tool. But only when stopped. Not quite ready for the mass market.)

big john

I joined a 500 member road club in 1989. Very few members had triples on their bikes but some did. Once compact doubles came out it was pretty much the end of triples for recreational/performance type riding.

I've had 2 touring bikes, multiple mountain bikes, and 2 sport bikes with triples. Still have a road bike with an Ultegra triple but I don't ride it often. I have nothing against them but when I got the bike with the compact double I found it has enough range for what I do, even with the 34x29 low. Modern compacts have way more range than the one I have and more range than the road triples I used to ride.

big john

I haven't seen a setup like you describe, sounds interesting.
With my stance I don't mind a wide Q-factor, within reason. I run 20mm pedal extenders because of toe out.

Ironfish653

In my limited experience with SS / FG on over-the-road rides (as opposed to track /city / messenger work) in a setup like 79pmooney is describing; each chainring is selected to work with one specific cog; providing three distinct ratios that you can pick, depending on the conditions (hills -v- flats). You still have to stop, loosen the rear wheel, move the chain to the desired cog / ring combo, and re-tighten the wheel before riding on .

Many single / FG hubs are threaded on both ends of the axle (aka flip-flop hubs) so you can run two different cogs, or a fixed cog on one side, and a single freewheel on the other, by flipping the wheel around; or what 79pmooney did, is got a second cog on one side, with the third on the other, giving three on the back wheel. I presume a conventional triple crank up front.
Good piece of work, that, getting all three to work, on the same chain, without running out of dropout.

Ironfish653

I don't see the FD as 'crude' but at the same time, they're a lot more particular about setup and technique, especially when combined with indexed integrated shifters.
In the 7/8/9-sp range, RDs are pretty much universal, with a fair amount of overlap with 10-sp hardware as well. A FD has a much smaller 'comfort zone' that it'll work with; a 9- or 10-sp road FD will work satisfactorily on a 53-39 road double crank, but a 7-sp triple FD intended for a 42t big ring, will be a mess trying to shift a 9/10 chain on a big double.

Front shifting is much improved since the SIS era, with ramps and pins to help move the chain, but it still needs to be pretty close, and it demands that the rider pay more attention during the shift (soft pedaling) to effect a smooth shift (and a lot of casual riders don't know this) Adding wear / poor adjustment to unsympathetic technique (shifting under load, etc) on a RD usually results in some pops and bangs, but usually delivers a shift; a blown front shift will often throw / drop the chain, either to the outside, free-spinning the crank, or to the inside, where it's sucked into the chainstay, crank, rear wheel, or a combination thereof.