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Does anyone yet make an affordable quad chainring? I would love to see a 4x12 with my staggered cog idea such that all 12 gears are shifted progressively using the 4 chainrings. Each chainring would engage only 3 cogs. I think the "double shifting" would be quite easy. On the gear indicator (1 thru 12), every 3rd gear could be marked with a different color number to indicate to the rider that a "double" shift is required next. Generally when the rider settles into a good pace on reasonably flat pavement, he/she will only be using 1 chainring and using the 3 gears for it to fine tune the cadence. For example, if the chainrings are labelled A,B,C and D and each cog for each of those chainrings is labeled 1 thru 3, someone might be using C2 gear but shift to C1 for a slight headwind and C3 for a slight tailwind.

I think it is a good and interesting idea and would look cool too.

I played around in a spreadsheet and came up with these ratios:

  1. 20/40 = 0.5
  2. 20/33 = 0.61
  3. 20/27 = 0.74
  4. 28/31 = 0.9
  5. 28/26 = 1.09
  6. 28/21 = 1.33
  7. 36/22 = 1.64
  8. 36/18 = 2
  9. 36/15 = 2.4
  10. 44/15 = 2.93
  11. 44/13 = 3.38
  12. 44/11 = 4.00

Notice that the 15 cog repeats cuz the difference between the 36 and 44 chainrings is close enough to 20%.

Also notice the overall spread of the gears is a very wide 8 with a very low 1st gear (0.5) and a reasonably tall high gear (4.0). That should cover almost any situation for the average rider.

  • This would be a lot of mess to come up with a solution that likely weighed more and had more failure points than say, a Rohloff hub, which would have 14 gears in 13.6% increments, as opposed to the 20% to 22% increments you have. The increments you are showing are also a bit too large for comfortably finding a gear for most experienced riders. – Deleted User Jan 22 '16 at 23:41
  • Well after paying close attention to what happens on my 3x7 (21 speed) mountain bike when I ride it on the street, I blast thru the lower gears in maybe 1 second (or less) and I am in the upper gears much longer so it makes to spread out the lower gears more (perhaps 30%). The other option if you even have closely spaced low gears is to double or triple shift the lower gears like from 1 to 3 or 1 to 4 for example. – David Jan 22 '16 at 23:48
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    That's fine until you are riding up a hill, into a strong wind, through mud, through snow or in the cold and can't find an appropriate gear. I spend a good portion of winter riding low gears. I'd throw a bike with 30% increments into passing traffic for a tractor trailer to dispose of. – Deleted User Jan 22 '16 at 23:57
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    I did say if you have close low gears to double or triple shift them if you dont need them. I sometimes even do this on my motorcycle if I dont need performance. I got from 1st to 3rd to 5th. I only have 5 gears. – David Jan 23 '16 at 0:00
  • @DeletedUser concur - I have access to 3 speed bikes at work, and they are hideously bad gearing with 0.66 / 1.0 and 1.33 – Criggie Jan 13 '18 at 1:40
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You could do this for the front with a Mountain Tamer Quad (which is an adapter which turns a triple into a quad) and an appropriately chosen front derailleur. The chainline issues become more severe than they do with a triple.

For the rear, you could use a 12 speed internal gear hub (Sachs Elan) or go up to 14 with a Rohloff Speedhub with a chain tensioner.

The question is why would you want to do this (like all your questions)? With 3x9's or 2x11's there are more than enough gear combinations that its pointless for riders to have more. With more gears, things have to be machined more carefully and become less robust as well. You need a good gear combination, not the perfect combination (though Nuvinci makes a CVT for bicycles). Also, who in their right mind looks at the cassette when shifting? Nobody. On top of this, front derailleurs are crude and sloppy devices just by how they work -- with 4 chain rings, you can get one to work depending on the chainring spacing, but probably not well.

So, while you could run a 4x12, it would be utterly useless for anyone who wants to ride.

  • I would want to do this cuz I would get a spread of 8 and good chain alignment. I don't see that happening with something like a 2x11. I have a cheap $100 BSO "MTB" and it shifts the front chainrings fairly well. Actually it shifts those better than the rear which doesn't hold cog 5 well. If my ideas dont relate well to the way you ride that is fine but don't generalize that my ideas are useless to everyone. I suspect others out there would love to have a quad chainring progressive 12 speed. Not everone who rides bikes is a serious street rider or racer. Some of us like to play for low $. – David Jan 21 '16 at 16:38
  • Also my reasoning for 4 chainrings is since the cassettes keep getting wider, the chainring spacings should widen as well to better "cover" the chain movement. Having 4 chainrings and 12 cogs would allow no more than about 1 chainwidth of "crosschaining" which is very minimal. I would just shift it as a progressive 12 speed, not a 48 speed. It makes good sense to me. – David Jan 21 '16 at 16:45
  • The biggest challenge would be to find a suitable front derailleur and a matching lever. Unless you're gifted with DIY. – Carel Jan 21 '16 at 20:27
  • Or you use a friction shifter. One of the links there uses a barcon + an ultegra derailluer. – Batman Jan 21 '16 at 21:01
  • @David I really don't see many people being interested in a system where you have to know exactly what gear you're in before you shift. It just sounds too complicated to use. Beginners have no clue when to shift anyway; stronger riders just shift up or down at the back, have a rough idea of where they are on the block and shift at the front when appropriate. So I don't see any niche for the system you propose: sure, some people will be interested in anything but I can't see any group of bicycle users that this system suits well. – David Richerby Jan 13 '18 at 12:36
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I've had a bike with a quad front chainring. It was on a Raleigh Delmara MTB originally, and shifting was dreadful. It had to be friction shifting because the chainrings were slightly closer together than normal, packing 4 chainrings in the width of 3.5 based on normal spacing.

Closer-squeezed chainrings lead to chatter and rub whenever the chain was on a small rear cog and anything but the big chainring. I could never shift it by feel either, had to watch it change because of the narrowness of the good slot.

I moved it to a mule bike with much longer 550mm chainstays and shifting improved, but it was never great.

In addition it was a 26 small chainring and 48 tooth large, so that provided no more range than a normal triple chainring.

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In short, nice idea but no real gain offered. Plus additional weight and finickyness.

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