Bicycle Mechanics - Is it possible to have a 12 x 12 speed? (144 speed)

12 chain rings on the back and an identical 12 on the front. Is this somehow possible? Wonder how it would ride.

Had a 3 cubed 27 speed bike in 1962, 3 speed hub, 3 cog cluster, triple crank.

I have a 30 speed now, 10 on the back, three in the front - but 144 would require two rear derailleurs to be used. sounds like an accident in the machine shop to put my feet anywhere near that much metal.

http://www.worksmartmompreneurs.com/blog/wp-content/uploads/2012/03/url.jpg

Well, a 14-speed Rohloff IGH used with a triple crank and a 7-speed cassette will give 294 possible combinations if you are enthralled by large numbers. But, as asked above "Why"?

SRAM dual drive, 10sp cassette and 3 to 5 chainrings. 90~150 gear combinations possible.

Anything's possible.

Nuvinci, unlimited gear ratios.

http://www.canosoarus.com/08LSRbicycle/LSR%20Bike02.htm if ya wanna go fast!

Think of trying to pedal a bike that has 9 more chainrings between your legs. It's easy enough to buy or build a bike that has unusable/unnecessary gears at each end of the range.

http://www.worksmartmompreneurs.com/blog/wp-content/uploads/2012/03/url.jpg

This.

One could build it but the redundancy and overlap would make shifting a nightmare and the effective range of gearing that a human being can turn is very small.

Why? Sheldon Brown's 63 speed bike. (http://sheldonbrown.org/otb.html)

It's an interesting project. Impractical, but fun to think about.

Hey, if you have to haul 1t of cargo on a bike, then 144sp could be quite desirable.

My Quetzal recumbent came with 105 combinations. Triple crank, 5 speed mid drive, 7 speed cluster on the back. I converted it to a Rohloff with a single chain ring. Still have 5 cogs on the mid drive, but no means to shift them other than by hand. All but one of the mid drive cogs put the input ratio lower than that stipulated by Rohloff, so they are just there to take up space on the freewheel.
Guess you could say it is technically a 70 speed though.

I'm still a believer that properly spaced 10x2 or 7x3 gives you all the gear combinations that the vast majority of riders will ever need. Heck, I remember when 12 and 15 speeds began replacing 10 speeds (5x2) and people were wondering what you needed all those gears for. There is a point where more adding gears for the sake of having more gears will produce one or more of three results: Gears so absurdly high or low as to be unusable, multiple redundant gear ratios, or gears with steps so small as to be insignificant and of no real benefit.

A friends dad same early 60's fixed up 2_3 speeds, one had 2 sprockets,
one on the hubshell . 2 chain loops..

clever machining could run 2 CV nuVinci hubs 1 driving the other, to widen the range..

SRAM dual drive, 10sp cassette and 3 to 5 chainrings. 90~150 gear combinations possible.
That's what came to mind for me to.

Edit: Just remembered.. do it old school. 63 speed yo. http://sheldonbrown.com/org/otb.html

Hey, if you have to haul 1t of cargo on a bike, then 144sp could be quite desirable.

More ratios does not mean more range. It would be interesting to see how many of the gear combinations overlap and how many are truly unique.

Just convert to a 1/4 inch pitch chain, instead of the current 1/2 inch chain.

Then you can put 20 cogs on the back.

Sheldon Brown's Nanodrive (http://sheldonbrown.com/nanodrive/index.html) system.

(Sheldon seems to have all the answers in this thread!)

SRAM dual drive, 10sp cassette and 3 to 5 chainrings. 90~150 gear combinations possible.

Don't forget to add a Schlumpf bottom bracket gear to double number of the gears

Why?

The cross-chaining possibilities would be endless.

But, the trim mechanism might need some thought.

Gears so absurdly high or low as to be unusable, multiple redundant gear ratios, or gears with steps so small as to be insignificant and of no real benefit.

The Megarange jump in the back is useful for those ridiculous hills that you're not going to climb on normal gears. You don't need to handle the range of crap nobody is going to climb with 5 or 6 mostly worthless cogs; put one big one there.

You know what would be even more interesting is a bike CVT. It's doable....

It would be gross.

I'm still a believer that properly spaced 10x2 or 7x3 gives you all the gear combinations that the vast majority of riders will ever need. Heck, I remember when 12 and 15 speeds began replacing 10 speeds (5x2) and people were wondering what you needed all those gears for. There is a point where more adding gears for the sake of having more gears will produce one or more of three results: Gears so absurdly high or low as to be unusable, multiple redundant gear ratios, or gears with steps so small as to be insignificant and of no real benefit.

Heh, for some reason, I thought you were younger than that. ;)

For what it's worth, I think Schwinn's 5-speeds gave enough range for most people (39-90 GI, roughly). But the jumps between gears would be hard to sell these days.

I'm still a believer that properly spaced 10x2 or 7x3 gives you all the gear combinations that the vast majority of riders will ever need. Heck, I remember when 12 and 15 speeds began replacing 10 speeds (5x2) and people were wondering what you needed all those gears for. There is a point where more adding gears for the sake of having more gears will produce one or more of three results: Gears so absurdly high or low as to be unusable, multiple redundant gear ratios, or gears with steps so small as to be insignificant and of no real benefit.
Well, we have a lot of bikes with absurdly high top gears. How many non-pro riders can make any real use of a 53x11 (or even a 50x12) high gear yet they are so common as to be nearly unavoidable on a newer road bike. "Absurdly low" low gears (<25 gear-inches) are another case as they do have their place on loaded touring and true off-road MTB riding.

From a historical perspective, every time an additional cog was added, there were those who loudly proclaimed it wasn't needed, the wheels would collapse, the chains would break, durability had gone out the window, etc. until they got used to N+1 only to repeat themselves the next time it happened. I've ridden 5,6,7,8,9 and 10-speed freewheels/cassettes and double and triple cranks over the past nearly 30 years and each increase brough some advantages and very few problems. There has to be a limit but I'm not ready to say where it is.

Hey, if you have to haul 1t of cargo on a bike, then 144sp could be quite desirable.

But what are you going to use for brakes?

12 chain rings on the back and an identical 12 on the front. Is this somehow possible? Wonder how it would ride.

Well since the rings are identical front and back we'd be looking at what, 11-32? So the top gearing will be kind of slow at only 3/1 gear ratio. You'd probably want a higher range in front, say at least up to 44 or so. So I think you'll also need a chain tensioning mechanism on the front as well as the back because of the large difference between the front rings.

That kind of defeats the purpose of having larger gaps in front with fewer rings (simplifying the chain handing and shifting that is), so my guess is that this is what generally prevents that kind of scheme. Probably any range greater than about the 20-teeth difference in a triple is going to require more complex chain guidance, either a longer tensioning arm on the rear or multiple tensioners. Unless you're just filling in the gaps between say 28 and 52 instead of extending the range (but it would still need a guide).

What's the point?

Your lowest speed is limited by how slowly you can pedal without falling over.
Your highest speed is limited by the power in your legs to overcome air resistance.

On a bicycle those upper and lower speed limits are really pretty close together. Suppose you could pedal at 70 MPH. A 144 gear transmission would require you to 1. skip over a bunch of gears 2. find a new gear twice per every MPH change or 3. constantly fish around through multiple gear combinations trying to find the "sweet spot" to match your speed and terrain.

What's the point?

Your lowest speed is limited by how slowly you can pedal without falling over.
Your highest speed is limited by the power in your legs to overcome air resistance.

On a bicycle those upper and lower speed limits are really pretty close together. Suppose you could pedal at 70 MPH. A 144 gear transmission would require you to 1. skip over a bunch of gears 2. find a new gear twice per every MPH change or 3. constantly fish around through multiple gear combinations trying to find the "sweet spot" to match your speed and terrain.

The bikes used for the human-powered speed records generally have 4 or 5 gears:
http://www.ohpv.org/events/albums/bm2004/varnas/pages/varnas16.htm

81 "gears" (3 x 3 x 9) is relatively common on recumbent trikes. I can't see that it's terribly useful unless you're winching up 10 to 15% grades all day.

Here is an example of a new drivetrain more like an Auto or motorcycle transmission

it's not hub centered, but in the lowest C of G on the frame.

some DH race bikes like the way the suspension reacts
without the IGH in the center. [and the vulnerability of derailleur mechs]
this is a touring oriented frame build.
http://www.en.tout-terrain.de/bicycles/silkroad-xplore/

More ratios does not mean more range. It would be interesting to see how many of the gear combinations overlap and how many are truly unique.

If you've ever had to haul heavy things, you'll want many many small steps between the gears. Especially so in low range. It doesn't matter if there is a ton of overlap, what you're looking for are small steps between gears so you don't lose momentum.

This is exactly why semi-trucks have 12+ gears

My recumbent has a mid drive, 5 speed mid and 7 speed rear, both with "rear" derailleurs. With this many gears I don't even bother trying to keep track of where I am. Each chain has only one front ring, so there is no cross chaining. You twist either grip clockwise to go faster and counterclockwise if cadence drops too low. Works well, and no issue with "front" shifting. I have never counted the teeth, and bought it used, so I really don't know what the ratios are, but I can go as fast as I go on my LeMond with 50/12, and have a much lower low. This setup is really nice, but wouldn't work on a diamond frame because there is not enough length between the crank and the rear wheel for two chain lines.

The bikes used for the human-powered speed records generally have 4 or 5 gears.
True but they are ridden only short distances and on completely flat courses. They are by no means general purpose bikes but have one very narrow focus.

There is a point where more adding gears for the sake of having more gears will produce one or more of three results: Gears so absurdly high or low as to be unusable, multiple redundant gear ratios, or gears with steps so small as to be insignificant and of no real benefit.

Small steps can be of great benefit given the modest human power curve; hence the NuVinci.

When you're cruising into a headwind using the closest ratios you can using a single ring of 1/2" pitch, your cruising speed is still uh, 'digitised' by the steps; a slight increase in resistance can mean you slow down 2 clicks instead of a poofteenth, when it happens at the edge of the ratio's range.

Now here's a thought: triple with half-step big rings instead of a granny. Prolly require a modified double FD, not to mention double cranks with spacers, I guess.

Half-step's a PITA to shift, but electronic possibilities beckon...

Small steps can be of great benefit given the modest human power curve...

But the question remains: how small can the steps be and still provide a useful difference? There's still some flexibility in the power source, and a change being noticeable doesn't automatically mean that the change will actually mean anything important in terms of endurance, speed or comfort. Would more resolution than offered by a corncob cassette actually be an improvement?

Sure, it you're on a trainer it's probably possible to notice real small increments in resistance, but riding IRL there's always a bunch of things influencing the ride. Roads dip & climb a little, wind picks up and fades, the pack surges and slows, you trade a few words with a fellow rider etc. In that setting, what's the smallest useful unit of change? 10%? 5%? 2%?

A few years back I was toying with the idea of using a 3-speed IGH together with a quad crank, (maybe a quarter-step setup?) which would have given me 12 separate gears with a spacing of something like 5.2-6.1 % or thereabouts. I eventually put that idea on hold, as I couldn't make it work with the shifters I wanted at the time. The range would have been a bit limited for my regular riding as well. But the concept still holds some interest. I may revisit it some time.